Patent Description:
An energy storage module may be linked to a renewable energy and power system, such as, for example, a solar cell, to store electric power when demand for electric power from a load is low and to use (or discharge or provide) the stored electric power when demand for electric power is high. The energy storage module generally includes (or is) an apparatus including a relatively large quantity of battery cells (e.g., secondary batteries or secondary battery cells). The energy storage module, which includes multiple battery cells, generally exhibits high-capacity and high-output characteristics.

The battery cells are generally received (or accommodated) in multiple trays, which are received (or accommodated) in a rack, and multiple racks are received (or accommodated) in a container box.

However, there have recently been instances in which a fire occurs in energy storage modules. And, once a fire starts in an energy storage module, it is not easy to extinguish due to the characteristics of the energy storage module. Thus, research into technology to increase the safety of the energy storage module is being actively conducted.

<CIT> relates to a safe, explosion-proof, square battery module.

<CIT> relates to a battery module including a fire extinguishing component and container, a battery box and a vehicle using said battery module.

<CIT> relates to a heat shield that slows down the propagation of a thermal runway between battery cells.

<CIT> relates to a rechargeable lithium battery.

<CIT> relates to the deposition of a conductive carbon coated polymer for high temperature lithium ion battery shutdown.

Embodiments of the present disclosure are related to an energy storage module exhibiting a reduced fire risk and increased safety by reducing or minimizing the chance of a fire spreading to adjacent battery cells when a fire occurs.

These and other aspects and features of the present disclosure will be described in or will be apparent from the following description of embodiments of the present disclosure.

According to an aspect of the present disclosure, an energy storage module includes: a plurality of battery cells arranged in a first direction such that long side surfaces of adjacent ones of the battery cells face one another, each of the battery cells including a vent; a plurality of insulation spacers, at least one of the insulation spacers being between the long side surfaces of each adjacent pair of the battery cells, each of the insulation spacers including a heat-insulating first sheet and a plurality of flame-retardant second sheets respectively adhered to opposite surfaces of the first sheet by an adhesion member; a cover member including an internal receiving space configured to accommodate the battery cells and the insulation spacers; a top plate coupled to a top of the cover member, the top plate including ducts respectively corresponding to the vents of the battery cells and having fire extinguishing agent openings respectively corresponding to the insulation spacers; a top cover coupled to a top of the top plate and having discharge openings respectively corresponding to the ducts; and an extinguisher sheet between the top cover and the top plate, the extinguisher sheet being configured to emit a fire extinguishing agent at a temperature exceeding a reference temperature.

The first sheet may include ceramic paper, and the second sheets may include mica paper.

The first sheet may include a ceramic fiber including an alkali earth metal.

The long side surfaces of adjacent ones of the battery cells may be spaced apart from each other by a first distance, and a thickness of each of the insulation spacers may be less than <NUM>% of the first distance.

When the fire extinguishing agent is emitted from the extinguisher sheet, the fire extinguishing agent may fill spaces between the insulation spacers and the battery cells through the fire extinguishing agent openings.

Each of the insulation spacers may have a width-direction size less than twice a height-direction size thereof, and the first sheet may be adhered to the second sheets at opposite ends thereof by the adhesion member.

The insulation spacers may further include an edge part including a plastic material, and the edge part may be formed at peripheral edges of the first and second sheets by insert molding.

The edge part may have a width in a range from <NUM> to <NUM>.

One surface of each of the insulation spacers may face the long side surface of one of the battery cells, and the other surface of each of the insulation spacers may face the long side surface of another one of the battery cells.

The first sheet and the second sheets may be spaced apart from each other at central portions thereof to form air passages.

The first sheet may be spaced apart from each of the second sheets by the adhesion member.

A width-direction size of the insulation spacers may be greater than twice a height-direction size thereof, and the first sheet and the second sheets may be adhered to each other by the adhesion member applied to a region adjacent top and bottom ends of each of the first sheet and the second sheets.

One surface of each of the insulation spacers may face the long side surfaces of two of the battery cells, and the other surface of each of the insulation spacers may face the long side surfaces of another two of the battery cells.

Each of the battery cells may include: a negative electrode including a negative electrode current collector, a negative electrode active material layer on the negative electrode current collector, and a negative electrode function layer on the negative electrode active material layer; and a positive electrode including a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector. The negative electrode function layer may include flake-shaped polyethylene particles, and the positive electrode active material layer may include a first positive electrode active material including at least one composite oxide of lithium and a metal selected from the group consisting of cobalt (Co), manganese (Mn), nickel (Ni) and a combination of these metals, and a second positive electrode active material including a compound represented by the Chemical Formula (<NUM>):.

wherein <NUM> ≤ a ≤ <NUM>, <NUM> ≤ x ≤ <NUM>, and M is Mn, Co, Ni or combinations thereof.

The flake-shaped polyethylene particles may have an average particle diameter (D50) in a range from <NUM> to <NUM>.

The flake-shaped polyethylene particles may have a thickness in a range from <NUM> to <NUM>.

The first positive electrode active material and the second positive electrode active material may be contained in a weight ratio in a range from <NUM>:<NUM> to <NUM>:<NUM>.

As described above, the energy storage module according to embodiments of the present disclosure suppresses ignition by providing a shut-down function to a battery cell by using compositions of negative and positive electrode active materials and can prevent or reduce heat from spreading to adjacent cells by rapidly extinguishing and cooling a battery cell when a vent of a battery cell opens (or ruptures) and/or when a fire occurs.

Hereinafter, embodiments of the present disclosure will be described in detail. The subject matter of the present disclosure, however, may be embodied in many different forms and should not be construed as being limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete and will convey the aspects and features of the present disclosure to those skilled in the art.

In addition, in the accompanying drawings, sizes or thicknesses of various components or layers may be exaggerated for brevity and clarity. In addition, it will be understood that when an element A is referred to as being "connected to" an element B, the element A can be directly connected to the element B or an intervening element C may be present therebetween such that the element A and the element B are indirectly connected to each other.

The terminology used herein is for the purpose of describing example embodiments of the present disclosure and is not intended to be limiting of the present disclosure. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise.

Further, the use of "may" when describing embodiments of the present disclosure relates to "one or more embodiments of the present disclosure. " Expressions, such as "at least one of," when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.

It will be further understood that the terms "comprise," "comprising," "include," "including," "has," and variations thereof, when used in this specification, specify the presence of the stated features, numbers, steps, operations, elements, and/or components but do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, and/or groups thereof. It will be understood that, although the terms first, second, etc. may be used herein to describe various members, elements, regions, layers, and/or sections, these members, elements, regions, layers, and/or sections should not be limited by these terms. These terms are used to distinguish one member, element, region, layer, and/or section from another. Thus, for example, a first member, a first element, a first region, a first layer, and/or a first section discussed below could be termed a second member, a second element, a second region, a second layer, and/or a second section without departing from the scope of the appended claims.

Spatially relative terms, such as "beneath," "below," "lower," "above," "upper," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "over" or "above" the other elements or features. Thus, the term "below" can encompass both an orientation of above and below.

Hereinafter, a configuration of an energy storage module according to embodiments of the present disclosure will be described.

<FIG> is a perspective view of an energy storage module according to an embodiment of the present disclosure, <FIG> is a partially enlarged view of the portion A of <FIG>, <FIG> is an exploded perspective view of the energy storage module shown in <FIG>, <FIG> is an exploded perspective bottom view of a bottom surface of an extinguisher sheet and of a top cover of the energy storage module shown in <FIG>, and <FIG> illustrates battery cells and insulation spacers arranged on a bottom plate of the energy storage module shown in <FIG>.

Referring to <FIG>, the energy storage module <NUM> according to an embodiment of the present disclosure includes a cover member <NUM>, battery cells <NUM>, insulation spacers <NUM>, a top plate <NUM>, an extinguisher sheet <NUM>, and a top cover <NUM>.

The cover member <NUM> provides an internal space for receiving (or accommodating) battery cells <NUM> and insulation spacers <NUM>. The cover member <NUM> includes a bottom plate <NUM>, an end plate (or a plurality of end plates) <NUM>, and a side plate (or a plurality of side plates) <NUM> which together form a space for accommodating the battery cells <NUM> and the insulation spacers <NUM>. In addition, the cover member <NUM> may fix positions of the battery cells <NUM> and the insulation spacers <NUM> and may protect the battery cells <NUM> from external impacts.

The battery cells <NUM> may be alternately arranged on a top surface of the bottom plate <NUM> of the cover member <NUM> with the insulation spacers <NUM> (e.g., with the insulation spacers <NUM> arranged between adjacent ones of the battery cells <NUM>). For example, the battery cells <NUM> may be arranged in a plurality of columns (e.g., two columns) along the top surface of the bottom plate <NUM> such that long side surfaces of the battery cells <NUM> face each other, and the insulation spacers <NUM> may be positioned between adjacent ones of the long side surfaces of the battery cells <NUM>.

Each of the battery cells <NUM> includes an electrode assembly accommodated in a case <NUM>. The electrode assembly may be configured by winding, stacking, or laminating a positive electrode plate and a negative electrode plate, each having a portion coated with an active material (e.g., a coating or coated portion), in a state in which a separator is positioned between the positive and negative electrode plates. A top portion of the case <NUM> may be sealed by a cap plate <NUM>. In addition, a vent 124a is located at roughly the center of the cap plate <NUM> and has a smaller thickness than other regions of the cap plate <NUM>. In addition, electrode terminals <NUM> and <NUM>, which are electrically connected to uncoated regions (e.g., uncoated portions) of the positive and negative electrode plates, may be exposed at an upper portion of the case <NUM> through the cap plate <NUM>. The electrode terminals <NUM> and <NUM> may be referred to as a first electrode terminal <NUM> and a second electrode terminal <NUM>, respectively, defining, for example, a negative electrode terminal and a positive electrode terminal, but the polarities thereof may be reversed. Occurrences of ignition of the battery cells <NUM> can be reduced by using particular compositions of active materials of the battery cells <NUM>, thereby increasing safety. Such active material compositions will be described in more detail below.

The insulation spacers <NUM> are positioned between each of (e.g., between adjacent ones of) the battery cells <NUM> to prevent the battery cells <NUM> from contacting one another, thereby maintaining the battery cells <NUM> (e.g., the cases <NUM> of the battery cells <NUM>) in an electrically isolated state. In addition, a reference distance or space (e.g., a predetermined distance) is maintained between each of the insulation spacers <NUM> and the battery cells <NUM> to establish external air passages (e.g., fire extinguishing agent passages), thereby allowing for the cooling of the battery cells <NUM>. The insulation spacers <NUM> may include a flame-retardant (or non-combustible) sheet that prevents (or substantially impedes) a fire from spreading to neighboring battery cells <NUM> and a heat-insulating sheet that prevents (or substantially impedes) heat from propagating to neighboring battery cells <NUM> when a fire starts in any of the battery cells <NUM>. Configurations of the insulation spacers <NUM> will be described in more detail below.

The top plate <NUM> is coupled to a top portion (e.g., a top surface or a top) of the cover member <NUM>. The top plate <NUM> may be coupled to the cover member <NUM> while covering top portions (e.g., top surfaces) of the battery cells <NUM>. In addition, the positive electrode terminals <NUM> and negative electrode terminals <NUM> of the battery cells <NUM> are exposed to (or through) the top plate <NUM>, and bus bars <NUM> are coupled to the respective terminals <NUM>/<NUM>, thereby connecting the battery cells <NUM> to one another in series, in parallel, or in series/parallel.

The top plate <NUM> includes a plurality of ducts <NUM> located to respectively correspond to the vents 124a, which are located on the top surface of each of the battery cells <NUM>. The ducts <NUM> may be arranged in one direction, for example, in a length direction of the top plate <NUM>. Accordingly, the gas discharged from the vent 124a of one of the battery cells <NUM> may move upwardly along a corresponding one of the ducts <NUM> of the top plate <NUM>. The configuration and operation of the ducts <NUM> will be described in more detail below.

The extinguisher sheet <NUM> is positioned between the top plate <NUM> and the top cover <NUM>. The extinguisher sheet <NUM> may be provided as one or more members (or sheets) extending in one direction, for example, in the length direction, of the top plate <NUM>. In addition, the extinguisher sheet <NUM> may include openings (e.g., opening holes) positioned to respectively correspond to the ducts <NUM> of the top plate <NUM>. Accordingly, the extinguisher sheet <NUM> may be positioned such that the openings therein are respectively aligned with the ducts <NUM> of the top plate <NUM>. In addition, the extinguisher sheet <NUM> may be coupled to a bottom surface 160b of the top cover <NUM>. Because the extinguisher sheet <NUM> is coupled to the bottom surface 160b of the top cover <NUM>, the extinguisher sheet <NUM> may be positioned above the top plate <NUM>. The configuration and operation of the extinguisher sheet <NUM> will be described below in more detail.

The top cover <NUM> is coupled to the top portion of the top plate <NUM>. The top cover <NUM> may cover the top plate <NUM> and the bus bars <NUM>. The top cover <NUM> also covers the extinguisher sheet <NUM>, which is coupled to the bottom surface 160b of the top cover <NUM>, thereby protecting the top plate <NUM>, the bus bars <NUM>, and the extinguisher sheet <NUM> from external impacts applied to a top surface 160a of the top cover <NUM>. In addition, the top cover <NUM> may include discharge openings (e.g., discharge holes) <NUM>. In addition, the top cover <NUM> may further include protrusion parts (e.g., a protrusions) <NUM> spaced a distance apart from the outer periphery of (e.g., may extend around a periphery of) respective ones of the discharge openings <NUM>, and the protrusion parts <NUM> downwardly protrude from the top cover <NUM>. Openings (e.g., opening holes) <NUM> of the extinguisher sheet <NUM> may be coupled to (e.g., may extend around) the exterior of respective ones of the protrusion parts <NUM>, and the ducts <NUM> may be coupled to (e.g., may extend into) the interior of the protrusion parts <NUM>. The discharge openings <NUM> may each include a plurality of discharge openings (e.g., discharge sub-openings) arranged in one direction, for example, in a length direction, of the top cover <NUM>. In addition, the discharge openings <NUM> may be positioned to respectively correspond to the ducts <NUM> of the top plate <NUM>. In addition, the discharge openings <NUM> may each be provided as a plurality of openings passing through the top and bottom surfaces of the top plate <NUM> and spaced apart from one another. Accordingly, the gases discharged from the vent 124a of the battery cell <NUM> when the vent 124a ruptures may be discharged to the exterior through the corresponding duct <NUM> of the top plate <NUM> and the corresponding discharge opening <NUM> of the top cover <NUM> and may facilitate user safety by preventing a user's hand from contacting the internal structure of the top cover <NUM>.

Hereinafter, the ducts <NUM> of the top plate <NUM> in the energy storage module <NUM> according to an embodiment of the present disclosure will be described in more detail.

<FIG> illustrates a portion of a rack accommodating a plurality of energy storage modules <NUM> according to an embodiment of the present disclosure, and <FIG> illustrate movement of gas from a battery cell <NUM> through a duct <NUM> in the energy storage module <NUM> shown in <FIG>. <FIG> illustrates an enlarged cross-sectional view taken along the line A-A of <FIG>, and <FIG> illustrates an enlarged cross-sectional view taken along the line B-B of <FIG>.

Referring to <FIG>, a rack <NUM> includes a plurality of shelves <NUM> and a plurality of the energy storage modules <NUM> accommodated on the shelves <NUM> of the rack <NUM>. The number of energy storage modules <NUM> may vary according to the desired capacity, and the energy storage modules <NUM> may be mounted in the rack <NUM> and then fixed thereto. The rack <NUM> may include a frame <NUM> defining the overall external shape of the rack <NUM> and shelves <NUM> at different layers of the frame <NUM> to support bottom portions (e.g., bottom surfaces) of the energy storage modules <NUM>. Here, a bottom surface of one of the energy storage modules <NUM> may contact a top surface of a first shelf <NUM>, and a bottom surface of another one of the energy storage modules <NUM> may be positioned on the top surface of a second shelf <NUM> while being spaced a distance apart from the top surface of the first shelf <NUM>. In <FIG>, two shelves <NUM> are shown in the frame <NUM> with energy storage modules <NUM> respectively mounted on the shelves <NUM>, but the present disclosure is not limited to the numbers in the illustrated embodiment.

In addition, as described above, the ducts <NUM> located on the top plate <NUM> respectively correspond to the vents 124a of the battery cells <NUM>. Referring to <FIG>, the gas discharged from one of the vents 124a may move upwardly along the duct <NUM>, as indicated by the arrows. In addition, if the vent 124a of a battery cell <NUM> ruptures, the gas may be discharged to the exterior through the discharge opening <NUM> of the top cover <NUM> positioned above the duct <NUM>. In some embodiments, a shelf <NUM> of the rack <NUM>, which supports another energy storage module <NUM>, is positioned over the top surface 160a of the top cover <NUM> so that the gas accumulates between the top surface 160a of the top cover <NUM> and the adjacent shelf <NUM>. A distance between the top surface 160a of the top cover <NUM> and the adjacent shelf <NUM> may be in a range from about <NUM> to about <NUM>. When the distance is greater than or equal to about <NUM>, the heat generated from the energy storage module <NUM> can be easily discharged to the exterior. When the distance is less than or equal to about <NUM>, a high-temperature inert gas atmosphere can be easily created, which will be further described below.

Specifically, when a gas begins to be discharged from a battery cell through a vent, a phase change may begin to occur in a fire extinguishing agent in the extinguisher sheet <NUM> at a temperature in a range from about <NUM> to <NUM>, and more specifically, a temperature in a range from <NUM> to <NUM>. However, even in this case, the fire extinguishing agent may remain inside the extinguisher sheet <NUM> instead of being sprayed (released) therefrom. Meanwhile, when, afterwards, the amount of gas discharged through the vent gradually increases and a temperature around the vent rises and reaches a temperature in a range from <NUM> to <NUM>, specifically, a temperature in a range from about <NUM> to <NUM>, and more specifically, a temperature in a range from <NUM> to <NUM>, a gas containing an electrolytic steam may be generated mainly through the vent. Also, the gas in the above temperature range may allow a heat-resistant plastic constituting an upper plate <NUM> and an upper cover <NUM> to remain unmelted. In addition, spraying of some of the fire extinguishing agent may begin. But if the separator melts due to a further increase in the internal temperature of the battery cell <NUM>, high-temperature inert gas may be generated with flames. As described above, the inert gas may fill a space between the top surface 160a of the top cover <NUM> and the adjacent shelf <NUM> to create an inert gas atmosphere, thereby preventing oxygen induction.

The inert gas can prevent flames generated by the battery cell <NUM> from spreading to neighboring battery cells <NUM> or to another energy storage module <NUM>. In addition, the extinguisher sheet <NUM>, which is positioned under the top cover <NUM>, may operate (e.g., may emit or spray the fire extinguishing agent) in response to the high-temperature inert gas, which will be described in more detail below.

Hereinafter, the configuration and operation of the extinguisher sheet <NUM> of the energy storage module <NUM> according to an embodiment of the present disclosure will be described in more detail.

<FIG> is a perspective view illustrating the extinguisher sheet <NUM> coupled to the top plate <NUM> in the energy storage module <NUM> according to an embodiment of the present disclosure. <FIG> is a partially enlarged view of the portion B of <FIG>. <FIG> are diagrams illustrating the operation of the extinguisher sheet <NUM> in the energy storage module <NUM> according to an embodiment of the present disclosure.

Referring to <FIG>, the extinguisher sheet <NUM> may be positioned between the top plate <NUM> and the top cover <NUM>, as described above. As shown in <FIG>, the extinguisher sheet <NUM> may have openings (e.g., opening holes) <NUM> respectively coupled to (e.g., extending around) the ducts <NUM> of the top plate <NUM>. Accordingly, movement of gas through the ducts <NUM> may not be influenced (or substantially influenced) by the extinguisher sheet <NUM>.

In addition, referring to <FIG>, the extinguisher sheet <NUM> may operate (e.g., may emit the fire extinguishing agent) in response to heat when the inert gas having a relatively high temperature of, for example, about <NUM>, is generated. The fire extinguishing agent contained in the extinguisher sheet <NUM> is emitted by (e.g., is sprayed from) the extinguisher sheet <NUM> in response to the high-temperature gas. In addition, because a top portion of the extinguisher sheet <NUM> is covered by the top cover <NUM>, the fire extinguishing agent may be directionally emitted (or sprayed) toward the bottom surface of the top cover <NUM>. In addition, the fire extinguishing agent may reach the underlying insulation spacers <NUM> through openings (e.g., fire extinguishing agent openings or opening holes) <NUM> located between adjacent ones of the ducts <NUM> of the top plate <NUM>. In addition, a fluid guide protrusion <NUM> may further be provided around the openings <NUM>, thereby efficiently guiding the movement of the fire extinguishing agent toward the insulation spacers <NUM>. As will be further described below, after reaching the insulation spacers <NUM>, the fire extinguishing agent may move along surfaces of the insulation spacers <NUM>, thereby extinguishing a fire on a battery cell <NUM> and cooling the battery cell <NUM>.

In addition, the extinguisher sheet <NUM> may include a capsule-type fire extinguishing agent received within (e.g., is accommodated or stored in) an external case. As described above, the extinguisher sheet <NUM> may emit the internal fire extinguishing agent such that the capsule-type fire extinguishing agent and the external case open (or rupture) when the gas passing through the duct <NUM> of the top plate <NUM> reaches a relatively high temperature of about <NUM>.

Hereinafter, configurations and operations of the battery cells <NUM> and the insulation spacers <NUM> in the energy storage module <NUM> according to an embodiment of the present disclosure will be described.

<FIG> is a cross-sectional view taken along the line C-C of <FIG>. <FIG> is a perspective view illustrating a configuration of an insulation spacer <NUM> according to an embodiment of the present disclosure. <FIG> are exploded perspective views illustrating example configurations of sheet parts of insulation spacers <NUM> according to an embodiment of the present disclosure. <FIG> is a cross-sectional view taken along the line D-D of <FIG> after the sheet parts are adhered to each other. <FIG> is a partially enlarged view of the portion C of <FIG>.

The battery cells <NUM> and insulation spacers <NUM> may be alternately arranged on a top surface of the bottom plate <NUM> of the cover member <NUM>. Here, the battery cells <NUM> may be arranged such that the long side surface of one of the battery cells <NUM> is spaced a distance (e.g., a reference or predetermined distance) apart from a long side surface of another (e.g., an adjacent) one of the battery cells <NUM>, and the insulation spacers <NUM> are positioned between the neighboring battery cells <NUM>. Here, the distance (e.g., a first distance) between the long side surfaces of the two neighboring battery cells <NUM> may be in a range from about <NUM> to about <NUM>. If the first distance is smaller than <NUM>, it is not easy to provide air layers between the battery cells <NUM> and the insulation spacers <NUM>, thereby lowering cooling efficiency. If the first distance is greater than <NUM>, the energy storage module <NUM> may become unnecessarily bulky.

The insulation spacers <NUM> positioned between each of the battery cells <NUM> may prevent the battery cells <NUM> from contacting each other, thereby maintaining the cases <NUM> of the battery cells <NUM> in an electrically isolated state. Each of the insulation spacers <NUM> may have a planar size corresponding to that of the long side surface of one battery cell <NUM>. For example, one surface of the insulation spacer <NUM> may face the long side surface of one battery cell <NUM>, and the other surface of the insulation spacer <NUM> may face the long side surface of another battery cell <NUM>.

In addition, the insulation spacer <NUM> and the long side surface of the battery cell <NUM> may be spaced apart by a distance (e.g., a second distance) to establish a passage for external air. The battery cell <NUM> may be cooled by the external air passing through the external air passage.

The insulation spacers <NUM> may include a sheet part (e.g., a sheet) <NUM> and an edge part (e.g., an edge) <NUM>. The sheet part <NUM> may include a flame-retardant (or non-combustible) sheet that prevents (or substantially impedes) a fire from spreading to neighboring battery cells <NUM> and a heat-insulating sheet that prevents (or substantially impedes) heat from being propagated to neighboring battery cells <NUM> when a fire starts in any of the battery cells <NUM>. In some embodiments, the sheet part <NUM> may include a heat-insulating first sheet 131a and a plurality of (e.g., two) flame-retardant (or non-combustible) second sheets 131b adhered to opposite surfaces of the first sheet 131a by one or more adhesion member(s) 131c. The sheet part <NUM> may have an increased heat insulating effect and may provide flame retardancy (and non-combustibility) by stacking multiple layers of the first sheet 131a and the second sheets 131b. For example, the insulation spacers <NUM> may prevent heat or flames from propagating to neighboring battery cells <NUM> through the stacked sheet parts <NUM> when the temperature of the battery cell <NUM> rises or flames are generated in the battery cell <NUM>.

Here, the first sheet 131a and the second sheets 131b may have the same size (e.g., the same length and width). To facilitate movement of the fire extinguishing agent, a thickness of the insulation spacer <NUM> may not exceed <NUM>% of the first distance (e.g., may not exceed <NUM>% of the distance between the adjacent battery cells <NUM>). For example, when the first distance is about <NUM>, the thickness of the insulation spacer <NUM> may not exceed about <NUM>. When the first distance is about <NUM>, the thickness of the insulation spacer <NUM> may not exceed about <NUM>. In one embodiment, the first sheet 131a may have a thickness in a range from about <NUM> to about <NUM>. In addition, each of the second sheets 131b may have a thickness in a range from about <NUM> to about <NUM>, and the adhesive member 131c may have a thickness of about <NUM>.

For example, the first sheet 131a may include (or may be formed of) ceramic paper, and the second sheets 131b may include (or may be formed of) mica (e.g. mica paper). In addition, the first sheet 131a may further include an aerogel. In this embodiment, because an air layer is sufficiently provided in the first sheet 131a, heat insulating efficiency can be increased. In addition, the first sheet 131a may include (or may be) ceramic paper made of a fiber-containing refractory insulating material. In addition, the first sheet 131a may include (or may be) bio-soluble fiber ceramic paper (e.g. ceramic fiber) containing an alkali earth metal, which is an eco-friendly high-temperature insulating material that is generally harmless to humans.

In addition, the sheet part <NUM> may have a configuration shown in <FIG>.

As shown in <FIG> and <FIG>, the adhesion member 131c is positioned between the opposite ends x1 of the first sheet 131a and each of the second sheets 131b so that the sheet part <NUM> has a reference (or predetermined) width. The adhesion member 131c may attach the first sheet 131a and the second sheets 131b to each other. In addition, the adhesion member 131c may have the same length as the first sheet 131a and the second sheets 131b in a length direction. For example, opposite ends x1 of the first sheet 131a may be adhered to respective opposite ends x1 of the second sheets 131b by the adhesion member 131c.

The adhesion member 131c may have a width in a range from about <NUM> to about <NUM>. Here, if the width of the adhesion member 131c is smaller than about <NUM>, adhesion between the first sheet 131a and the second sheets 131b may be insufficient. If the width of the adhesion member 131c is greater than about <NUM>, an ignition probability may increase due to the adhesion member 131c.

The adhesion member 131c may have a variety of adhesive components or configurations, such as a double sided tape or an adhesive tape, but the adhesive components and configurations of the adhesion member 131c are not limited thereto.

The adhesion member 131c may attach (e.g., may only attach) the opposite ends x1 of the first sheet 131a to the second sheets 131b so that the first sheet 131a and the second sheets 131b are spaced apart from each other at a central portion x2 of the sheet part <NUM>. As a result, air passages 131d may be established between the first sheet 131a and the second sheets 131b. In addition, if the sheet part <NUM> is compressed due to swelling of the battery cell(s) <NUM>, the air passages 131d established at the central portion x2 of the sheet part <NUM> may reduce (or mitigate) compression of the sheet part <NUM>.

As shown in <FIG>, according to another embodiment, the adhesion member 131c may be located at an area at (or adjacent to) top and bottom ends of the first sheet 131a to attach the first sheet 131a and the second sheets 131b to each other. In addition, the adhesion member 131c may have the same width as the first sheet 131a and the second sheets 131b in a width direction. For example, the top and bottom ends of the first sheet 131a may be respectively adhered to top and bottom ends of the second sheets 131b by the adhesion member 131c.

When the sheet part <NUM> has a width-direction size less than twice a height-direction size thereof, as shown in <FIG>, the adhesion member 131c may be attached to the opposite ends of the sheet part <NUM>. However, when the width-direction size of the sheet part <NUM> is greater than or equal to twice the height-direction size thereof, an adhesion area (e.g., a vertical adhesion area) may be reduced relative to the overall area of the sheet part <NUM> due to an area occupied by the adhesion member 131c attached to the opposite ends of the sheet part <NUM>, thereby lowering adhesion performance. Therefore, when the width-direction size of the sheet part <NUM> is greater than twice the height-direction size, the adhesion member 131c may be applied to the top and bottom ends thereof to increase the adhesion area, thereby improving the adhesion performance. The configuration of the sheet part <NUM> shown in <FIG> may be substantially the same as the sheet part <NUM> shown in <FIG> and <FIG>, except for positions of the adhesion member(s) 131c.

Further, when the adhesion member 131c is applied to the top and bottom ends of the sheet part <NUM>, the adhesion performance is improved, and in some embodiments, no edge part (described below) may be separately required (e.g., an edge part may be omitted).

In some embodiments, an edge part <NUM> may be provided along peripheral edges of the sheet part <NUM>. The edge part <NUM> may include (or may be made of) a plastic material, such as a general polyethylene or polypropylene, and may be coupled to edges of the sheet part <NUM> by using an insert molding to fix the shape of the sheet part <NUM>. In some embodiments, the edge part <NUM> may have a width in a range from about <NUM> to about <NUM>. If the width of the edge part <NUM> is smaller than about <NUM>, the sheet part <NUM> may not be easily fixed, and if the width of the edge part <NUM> is greater than about <NUM>, an ignition probability of the edge part <NUM> made of a plastic material may be increased.

As described above, when a fire extinguishing agent is applied from top portions of the insulation spacers <NUM>, the fire extinguishing agent may move downwardly along the surfaces of the sheet part <NUM>. Therefore, the fire extinguishing agent may contact the case <NUM> of the adjacent battery cells <NUM>, thereby performing extinguishing and cooling operations on the battery cells <NUM>. Hereinafter, movement of the fire extinguishing agent will be described in greater detail.

As shown in <FIG>, the top plate <NUM> may further include the openings <NUM> respectively located to correspond to (e.g., located over or above) the insulation spacers <NUM>. Accordingly, the fire extinguishing agent, when emitted from the extinguisher sheet <NUM>, may pass through the top plate <NUM> through the openings <NUM> of the top plate <NUM> to reach the insulation spacers <NUM>. In addition, the fire extinguishing agent may move along surfaces of the insulation spacers <NUM> that face the case <NUM> of the adjacent battery cells <NUM>, thereby extinguishing a fire and cooling the battery cells <NUM>. The fire extinguishing agent is emitted by the extinguisher sheet <NUM> located over one or more of the battery cells <NUM>, the temperature of which is higher than a reference temperature (e.g. <NUM>). Therefore, the fire extinguishing agent may be sprayed from a top portion of the battery cell <NUM> having an elevated temperature. In addition, because the fire extinguishing agent moves along the surfaces of the insulation spacers <NUM> positioned at front and rear sides of the corresponding battery cell <NUM>, both extinguishing and cooling of the corresponding battery cell <NUM> can be performed.

Hereinafter, a configuration of an energy storage module according to another embodiment of the present disclosure will be described.

<FIG> is a perspective view of an energy storage module according to another embodiment of the present disclosure. <FIG> is a perspective bottom view of the energy storage module shown in <FIG>, <FIG> is a cross-sectional view taken along the line E-E of <FIG>, and <FIG> is a perspective view illustrating battery cells and insulation spacers arranged on a cover member of the energy storage module shown in <FIG>.

Referring to <FIG>, the energy storage module <NUM> according to another embodiment of the present disclosure includes a cover member <NUM>, battery cells <NUM>, insulation spacers <NUM>, a top plate <NUM>, an extinguisher sheet <NUM>, and a top cover <NUM>.

The cover member <NUM>, the top plate <NUM>, the extinguisher sheet <NUM>, and the top cover <NUM> may be similarly configured to those of the energy storage module <NUM> described above. In addition, the battery cells <NUM> may be the same (or substantially the same) as those of the energy storage module <NUM>. Accordingly, the following description will focus on differences between the energy storage module <NUM> and the energy storage module <NUM>.

The cover member <NUM> may include a bottom plate <NUM>, an end plate (or a plurality of end plates) <NUM>, and a side plate (or a plurality of side plates) <NUM> which together form a space in which the battery cells <NUM> and the insulation spacers <NUM> are alternately arranged with the battery cells <NUM> on the bottom plate <NUM>. In addition, the cover member <NUM> may fix positions of the battery cells <NUM> and the insulation spacers <NUM> and may protect the battery cells <NUM> from external impacts. In addition, the bottom plate <NUM> may further include openings (e.g., through-holes) 211a, through which the fire extinguishing agent from the extinguisher sheet <NUM> and the air moving along the exterior surfaces of the insulation spacers <NUM> are exhausted. The openings 211a may be positioned to correspond to the insulation spacers <NUM>.

The insulation spacers <NUM> are positioned between adjacent ones of the battery cells <NUM> to prevent the battery cells <NUM> from contacting one another, thereby maintaining the cases <NUM> of the battery cells <NUM> in electrically isolated states. Each of the insulation spacers <NUM> may have short side surfaces, each having a planar size sufficient to entirely cover the long side surfaces of two adjacent battery cells <NUM>. For example, one of the insulation spacers <NUM> may be positioned between each group of four adjacent battery cells <NUM>, which are arranged such that long side surfaces of two of the four battery cells <NUM> face each other. In addition, a distance is maintained between each of the insulation spacers <NUM> and the battery cells <NUM> to establish external air passages and/or fire extinguishing agent passages, thereby allowing for cooling of the battery cells <NUM>. The insulation spacers <NUM> may include (or may be made of) a flame-retardant (or non-combustible) sheet that prevents (or substantially mitigates) a fire from spreading to neighboring battery cells and a heat-insulating sheet that prevents (or substantially mitigates) heat from propagating to neighboring battery cells when a fire outbreaks in any of the battery cells <NUM>. The configurations of the insulation spacers <NUM> will be described in more detail below.

The top plate <NUM> is coupled to a top portion of the cover member <NUM>. The top plate <NUM> may be coupled to the cover member <NUM> while covering top portions of the battery cells <NUM>.

The top plate <NUM> includes ducts <NUM> respectively corresponding to the vents 124a located on a top surface of each of the battery cells <NUM>. The ducts <NUM> may be arranged in one direction, for example, in a length direction of the top plate <NUM>. Accordingly, if the vent 124a ruptures, the gas discharged through the vent 124a of the battery cell <NUM> may move upwardly along the ducts <NUM> of the top plate <NUM>.

The extinguisher sheet <NUM> is positioned between the top plate <NUM> and the top cover <NUM>. The extinguisher sheet <NUM> may include a plurality of planar sheets located at opposite sides of the ducts <NUM> of the top plate <NUM> and extending in a length direction of the top plate <NUM>. The extinguisher sheet <NUM> may be mounted on a bottom surface 260b of the top cover <NUM>. Here, the length direction may refer to a direction in which the ducts <NUM> of the top plate <NUM> extend.

The top cover <NUM> is coupled to the top portion of the top plate <NUM>. The top cover <NUM> may cover the top plate <NUM> and the extinguisher sheet <NUM>, thereby protecting the top plate <NUM> and the extinguisher sheet <NUM> from external impacts applied to a top surface 260a of the top cover <NUM>. In addition, the top cover <NUM> may include discharge openings (e.g., discharge holes) <NUM>. In addition, the top cover <NUM> may also include protrusion parts (e.g., protrusions) <NUM> spaced apart from (e.g. may extend around) the outer periphery of respective ones of the discharge openings <NUM>. The protrusion parts <NUM> may protrude downwardly. The ducts <NUM> may be respectively coupled to (e.g., may respectively extend into) the interior of the protrusion parts <NUM>. Each of the discharge openings <NUM> may include a plurality of discharge holes arranged in one direction, for example, in a length direction of the top cover <NUM>. In addition, the discharge openings <NUM> may be positioned to correspond to the ducts <NUM> of the top plate <NUM>. In addition, the discharge openings <NUM> may also be provided as a plurality of openings passing through top and bottom surfaces of the top cover <NUM> and spaced apart from one another. Accordingly, if the vent 124a ruptures, the gas discharged from the vent 124a of the battery cell <NUM> may be discharged to the exterior side along the duct <NUM> of the top plate <NUM> and the discharge opening <NUM> of the top cover <NUM>.

In addition, the top cover <NUM> may further include openings (e.g., through-holes) <NUM>, through which the fire extinguishing agent of the extinguisher sheet <NUM> is exhausted and the air moving along the exterior surfaces of the insulation spacers <NUM> is exhausted. The openings <NUM> may be positioned to respectively correspond to the insulation spacers <NUM>.

In addition, recess parts (e.g., recessed portions or recesses) <NUM>, each having a lower height (e.g., a lower height above the battery cells <NUM>) than other areas of the top cover <NUM>, may be provided in a length direction of the top cover <NUM>, and the discharge openings <NUM> may be arranged at the recess parts <NUM>. With this configuration, the gases discharged through the ducts <NUM> and the discharge opening <NUM> may gather in the recess parts <NUM>, and the gas may be discharged to the exterior side by using, for example, a separate fan or a suction structure (e.g., a vacuum), thereby allowing the gas generated by the battery cells <NUM> to be discharged quickly.

Hereinafter, configurations and operations of battery cells <NUM> and insulation spacers <NUM> in an energy storage module according to another embodiment of the present disclosure will be described.

<FIG> are a perspective view and a cross-sectional view, respectively, illustrating configurations of insulation spacers to be used in the energy storage module <NUM> according to another embodiment of the present disclosure, and <FIG> is a cross-sectional view taken along the line F-F of <FIG>.

The battery cells <NUM> and the insulation spacers <NUM> may be alternately arranged on a top surface of the bottom plate <NUM> of the cover member <NUM>. Each of the insulation spacers <NUM> may have short side surfaces, each having a planar size sufficient to entirely cover long side surfaces of two adjacent battery cells <NUM>. For example, one surface of one of the insulation spacers <NUM> may entirely cover the long side surfaces of two adjacent battery cells <NUM>, and the other surface of the one insulation spacer <NUM> may entirely cover the long side surfaces of two other adjacent battery cells <NUM>. For example, one of the insulation spacers <NUM> may be positioned between four battery cells <NUM> that are arranged such that long side surfaces of two battery cells <NUM> face long side surfaces of two other battery cells <NUM>.

In addition, long side surfaces of the battery cells <NUM> may be spaced apart from long side surfaces of facing battery cells <NUM>, and the insulation spacers <NUM> may be positioned between each of the long side surfaces of the battery cells <NUM>.

A distance (e.g., a first distance) between the long side surfaces of the facing battery cells <NUM> may be in a range from about <NUM> to about <NUM>. If the first distance is smaller than about <NUM>, air layers (e.g., air passages) may not be provided between each of the battery cells <NUM> and the insulation spacers <NUM>, thereby lowering cooling efficiency. If the first distance is greater than about <NUM>, the energy storage module <NUM> may become unnecessarily bulky.

The insulation spacers <NUM>, positioned between each facing pair of the battery cells <NUM>, may prevent the battery cells <NUM> from contacting each other, thereby maintaining the cases <NUM> of the battery cells <NUM> in electrically isolated states. In addition, the insulation spacer <NUM> and the long side surfaces of battery cells <NUM> are spaced apart from each other to establish external air passages. Here, the battery cells <NUM> may be cooled by external air moving along (or through) the external air passages.

The insulation spacers <NUM> may consist of sheets <NUM> (e.g., only sheets <NUM>) without separate edge parts. The insulation spacers <NUM> may include a flame-retardant (or non-combustible) sheet that prevents (or substantially mitigates) the fire from spreading to neighboring battery cells <NUM> and a heat-insulating sheet that prevents (or substantially mitigates) heat from propagating to neighboring battery cells <NUM>. For example, the sheet parts <NUM> of the insulation spacers <NUM> may include a heat-insulating first sheet 231a and two flame-retardant (or non-combustible) second sheets 231b respectively adhered to opposite surfaces of the first sheet 231a by using one or more adhesive member(s) 231c. The first sheet 231a and the second sheets 231b have the same (or substantially the same) size. A thickness of the insulation spacer <NUM> may not exceed about <NUM>% of the first distance to facilitate movement of the fire extinguishing agent, which will be described in more detail below.

The adhesion member 231c may be positioned between the first sheet 231a and the second sheets 231b at a distance (e.g., a reference distance) from top and bottom ends of the first sheet 231a to attach the first sheet 231a and the second sheets 231b to each other. In addition, the adhesion member 231c may have the same (or substantially the same) width as the first sheet 231a and the second sheets 231b in their width directions. For example, the top and bottom ends of the first sheet 231a may be respectively adhered to top and bottom ends of the second sheet 231b by the adhesion member 231c.

When the sheet part <NUM> has a width-direction size greater than twice a height-direction size thereof, the adhesion member 231c may be applied to the top and bottom ends thereof to improve adhesion performance. For example, when the sheet part <NUM> has the width-direction size greater than twice the height-direction size thereof, the adhesion performance may be lowered when the adhesion member 231c is applied to opposite ends of the sheet part <NUM>, such as in the embodiment shown in <FIG>, due to a reduction in the adhesion area. In this case, the insulation spacer <NUM> may have the same (or substantially the same) configuration as the sheet part <NUM> as shown in <FIG>.

As discussed above, if a fire extinguishing agent is applied from top portions of the insulation spacers <NUM>, the fire extinguishing agent may move downwardly along the surfaces of the sheet part <NUM>. Therefore, the fire extinguishing agent may contact the case <NUM> of the adjacent battery cells <NUM>, thereby extinguishing a fire and cooling the battery cells <NUM>. Hereinafter, the movement of the fire extinguishing agent and the cooling of the battery cells <NUM> using the air will be described in greater detail.

As shown in <FIG>, the top plate <NUM> may further include openings (e.g., opening holes) <NUM> located to respectively correspond to the insulation spacers <NUM>. Accordingly, the fire extinguishing agent emitted from the extinguisher sheet <NUM> may pass through the top plate <NUM> through the openings <NUM> of the top plate <NUM> to reach the insulation spacers <NUM>. In addition, the fire extinguishing agent may move along surfaces of the insulation spacers <NUM> that face the case <NUM> of the battery cells <NUM>, thereby extinguishing and cooling the battery cells <NUM>. The fire extinguishing agent is emitted (or sprayed) from the extinguisher sheet <NUM> above one or more of the battery cells <NUM>, the temperature of which is higher than a reference temperature. Therefore, the fire extinguishing agent may be sprayed from a top portion of the battery cell <NUM>, the temperature of which has increased. In addition, because the fire extinguishing agent moves along the surfaces of the insulation spacers <NUM> positioned at front and rear sides of the corresponding battery cell <NUM>, the corresponding battery cell <NUM> can be both extinguished and cooled.

In addition, the top cover <NUM> may further include openings <NUM> that pass through top and bottom surfaces of the top cover <NUM> and are located to respectively correspond to the openings <NUM>. For example, the openings <NUM> may respectively correspond to the insulation spacers <NUM>.

In addition, the bottom plate <NUM> of the cover member <NUM> may also include openings 211a located to respectively correspond to the insulation spacers <NUM>. Thus, air introduced through the openings <NUM> of the top cover <NUM> and the openings <NUM> of the top plate <NUM> may move along spaces provided between the insulation spacers <NUM> and the battery cells <NUM> to be discharged through the openings 211a of the bottom plate <NUM>. Of course, the movement of the air (e.g., the airflow direction) may be reversed. In such a way, air passages may be provided by the openings 211a, <NUM>, and <NUM>, thereby improving cooling efficiency.

Hereinafter, the active material composition of the battery cell <NUM> used in the energy storage modules <NUM> and <NUM> according to an embodiment of the present disclosure will be described in greater detail.

<FIG> and <FIG> are a perspective view and a cross-sectional view, respectively, of a battery cell used in an energy storage module according to an embodiment of the present disclosure.

Referring to <FIG> and <FIG>, a battery cell <NUM> is configured such that an electrode assembly <NUM> is accommodated in a case <NUM> and a cap plate <NUM> covers a top portion of the case <NUM>. In addition, a vent 124a having a smaller thickness than other regions is located roughly at the center of the cap plate <NUM>. A duct <NUM> of the top plate <NUM> is located to correspond to a top portion of a vent 124a, as described above.

In addition, the electrode assembly <NUM> may be electrically connected to a first electrode terminal <NUM> and a second electrode terminal <NUM> located on the cap plate <NUM> through a pair of current collectors <NUM>. For convenience sake, in the following description, the first electrode terminal <NUM> will be referred to as a negative electrode terminal and the second electrode terminal <NUM> will be referred to as a positive electrode terminal, but polarities thereof may also be reversed.

The electrode assembly <NUM> may include a negative electrode 125a, a positive electrode 125b positioned to face the negative electrode 125a and a separator 125c positioned between the negative electrode 125a and the positive electrode 125b, and the electrode assembly <NUM> may be accommodated in the case <NUM> together with an electrolyte.

Here, the negative electrode 125a may include a negative electrode current collector, a negative electrode active material layer positioned on the negative electrode current collector, and a negative electrode function layer positioned on the negative electrode active material layer.

Compared to a case where the negative electrode function layer includes spherical polyethylene particles, in a case where the negative electrode function layer includes flake-shaped polyethylene particles, the reaction depending on the temperature may speed up under the same reaction conditions, thereby further increasing a safety improving effect of a lithium secondary battery.

The flake-shaped polyethylene particles yet to be melted may be distributed to cover pores over a thinner and wider area than the spherical polyethylene particles yet to be melted. If the polyethylene particles are melted at a temperature higher than a set or predetermined temperature to shut down ion passages, a larger electrode plate area may be shut down by the flake-shaped polyethylene particles than by the melted spherical polyethylene particles, thereby increasing the reaction speed.

That is to say, during thermal runaway of a battery cell, the polyethylene particles included in the negative electrode function layer are melted to shut down ion passages, so that ion movement is restricted and a shut-down function is manifested, thereby preventing additional electrochemical reactions from taking place (or thereby reducing a likelihood or degree of the additional electrochemical reactions).

For example, as confirmed from <FIG>, since the flake-shaped polyethylene particles according to an embodiment of the present disclosure are distributed over pores in the composition of the negative electrode function layer throughout a thin and wide area, they are quickly melted down during thermal runaway due to thermal/physical impacts, thereby demonstrating an excellent effect in blocking ion passages.

In general, polyethylene may be categorized by density into high-density polyethylene (HDPE) (Density: <NUM>/cc to <NUM>/cc), medium-density polyethylene (MDPE) (Density: <NUM>/cc to <NUM>/cc), low-density polyethylene (LDPE) (Density: <NUM>/cc to <NUM>/cc), and very low density polyethylene (VLDPE) (Density: <NUM>/cc to <NUM>/cc).

The flake-shaped polyethylene particles may be used alone or in mixture of two or more polyethylene (PE) polymers, such as, for example, HDPE, MDPE, or LDPE.

The flake-shaped polyethylene particles included in the negative electrode function layer positioned on the negative electrode active material layer may have an average particle diameter (D50) in a range from <NUM> to <NUM>, specifically from <NUM> to <NUM>.

Unless defined otherwise in the specification of the present disclosure, an average particle diameter (D50) may be measured using any suitable method generally used in the art such as, for example, by utilizing a particle size analyzer, or by utilizing a transmission electron microscopic (TEM) image or a scanning electron microscopic (SEM) image. Also, the D50 may be easily measured by analyzing data measured by a measuring device using a dynamic light-scattering method to count the number of particles for each particle size range and calculating an average value thereof. In some embodiments, the D50 value may correspond to a particle size at which half of the mass (or volume) of the particles have a larger particle size and the other half of the mass (or volume) of the particles have a smaller particle size.

Meanwhile, a ratio of a major axis length to a minor axis length of the flake-shaped polyethylene particles may be in a range from <NUM> to <NUM>, for example, <NUM> to <NUM>, or <NUM> to <NUM>.

In addition, the flake-shaped polyethylene particles may have a thickness in a range from <NUM> to <NUM>, or between <NUM> and <NUM>, for example, between <NUM> and <NUM>.

As shown in <FIG>, the polyethylene particles according to the present disclosure have a flake-shape and have a different shape from general polyethylene particles having a spherical shape in a water-dispersible state, as shown in <FIG>. An average particle size of the flake-shaped polyethylene particles may be defined to be D50, which is a particle size at <NUM>% of a volume ratio (or a mass ratio) in a cumulative size-distribution curve.

The negative electrode function layer may further include inorganic particles and a binder.

The flake-shaped polyethylene particles and the inorganic particles and the binder may be contained in the negative electrode function layer in a weight ratio in a range from <NUM>:<NUM> to <NUM>:<NUM>, for example, <NUM>:<NUM> to <NUM>:<NUM>.

If the content (e.g., amount or weight ratio) of the flake-shaped polyethylene particles and the inorganic particles is within the range stated above, cycle-life characteristics and output power characteristics of rechargeable lithium battery cells including the same can be obtained or improved.

The inorganic particles may include, for example, Al<NUM>O<NUM>, SiO<NUM>, TiO<NUM>, SnO<NUM>, CeO<NUM>, MgO, NiO, CaO, GaO, ZnO, ZrO<NUM>, Y<NUM>O<NUM>, SrTiO<NUM>, BaTiO<NUM>, Mg(OH)<NUM>, boehmite or combinations thereof, but aspects of the present disclosure are not limited thereto. In addition to the inorganic particles, the negative electrode function layer may further include organic particles including an acryl compound, an imide compound, an amide compound or combinations thereof, but aspects of the present disclosure are not limited thereto.

The inorganic particles may have spherical shapes, sheet-shapes, cubic shapes or amorphous shapes. An average particle diameter (e.g., D50) of the inorganic particles may be in a range from about <NUM> to about <NUM>. Within the range stated above, the average particle diameter of the inorganic particles may be in a range from about <NUM> to about <NUM>, or from about <NUM> to about <NUM>, for example, from about <NUM> and about <NUM>. The average particle diameter of the inorganic particles may be a particle size (D50) at <NUM>% of a volume ratio (or a mass ratio) in a cumulative particle size-distribution curve.

The negative electrode function layer may have a thickness in a range from <NUM> to <NUM>, or, for example, between <NUM> and <NUM>.

A ratio of the thickness of the negative electrode active material layer to the thickness of the negative electrode function layer may be in a range from <NUM>:<NUM> to <NUM>:<NUM>, for example, <NUM>:<NUM> to <NUM>:<NUM>.

If the thickness of the negative electrode function layer is within the foregoing range, thermal stability of the resultant rechargeable lithium battery can be remarkably improved while maintaining excellent cycle life characteristics.

In some embodiments, if the thickness ratio of the negative active material layer to the negative electrode function layer is within the range stated above, thermal stability of the resultant rechargeable lithium battery can be improved while minimizing or reducing a reduction in the energy density.

Usable examples of the negative electrode current collector may include a copper foil, a nickel foil, a stainless steel foil, a titanium foil, a nickel foam, a copper foam, a polymer substrate coated with a conductive metal, or a combination thereof.

Usable examples of the negative electrode active material may include a material capable of reversibly intercalating/deintercalating lithium ions, a lithium metal, a lithium metal alloy, a material being capable of doping/undoping lithium, or a transition metal oxide.

Examples of the material capable of reversibly intercalating and deintercalating the lithium ions may include a carbon material, e.g., any suitable carbon-based negative electrode active material generally used in a lithium secondary battery. Representative examples of the carbon-based negative electrode active material may include crystalline carbon, amorphous carbon, and mixtures thereof. Examples of the crystalline carbon may include graphite, such as amorphous, sheet-shaped, flake-shaped, spherical shaped, or fiber-shaped natural graphite or artificial graphite. Examples of the amorphous carbon may include soft carbon or hard carbon, a mesophase pitch carbonized product, fired coke, or the like.

The crystalline carbon may include graphite of non-shaped (amorphous), sheet-shaped, flake-shaped, spherical-shaped, and/or fiber-shaped natural graphite and/or artificial graphite. The amorphous carbon may be a soft carbon, a hard carbon, mesophase pitch carbide, fired coke, and/or the like.

Usable examples of the lithium metal alloy may include an alloy of lithium and a metal selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

Examples of the material being capable of doping/undoping lithium may include a silicon-based material, e.g., Si or SiOx (<NUM><x<<NUM>), an Si-Q alloy (wherein the Q is an element selected from the group consisting of an alkali metal, an alkaline-earth metal, Group <NUM> to <NUM> elements, a transition metal, a rare earth element, or a combination thereof, and is not Si), a Si-C composite, Sn, SnO<NUM>, Sn-R (wherein the R is an element selected from the group consisting of an alkali metal, an alkaline-earth metal, Group <NUM> to <NUM> elements, a transition metal, a rare earth element, or a combination thereof, and is not Sn), a Sn-C composite, and the like, and at least one of which may be used in a mixture with SiO<NUM>. Usable examples of the elements Q and R may be selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof.

The transition metal oxide may include a lithium titanium oxide.

In the negative electrode active material layer, the negative electrode active material may be included in an amount in a range from <NUM> wt % to <NUM> wt % based on the total weight of the negative active material layer.

Optionally, the negative electrode active material layer may further include a negative electrode conductive material and a negative electrode binder.

Each of the negative electrode conductive material and the negative electrode binder may be included in an amount in a range from <NUM> wt% to <NUM> wt% based on the total weight of the negative active material layer.

The negative electrode conductive material is used to improve the conductivity (e.g., electrical conductivity) of a negative electrode. Any suitable electrically conductive material may be used as the negative electrode conductive material, unless the material causes a chemical change (e.g., an undesirable or unwanted change to any of the components of the rechargeable lithium battery). Examples of the negative electrode conductive material may include a carbon-based material, such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber and the like; a metal-based material, such as a metal powder or a metal fiber and the like of copper, nickel, aluminium, silver, and the like; a conductive polymer, such as a polyphenylene derivative and the like; or a mixture thereof.

The negative electrode binder may serve to improve binding properties of the negative active material particles with one another and with a current collector. Examples of the negative electrode binder may include a non-water-soluble binder, a water-soluble binder, an amphiprotic binder, or a combination thereof.

Examples of the non-water-soluble binder may include polyvinylchloride, carboxylated polyvinylchloride, polyvinylfluoride, an ethylene oxide-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidenfluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.

Examples of the water-soluble binder may include a styrene-butadiene rubber, an acrylated styrene-butadiene rubber, polyvinyl alcohol, sodium polyacrylate, a copolymer of propylene and a C2 to C8 olefin, a copolymer of (meth)acrylic acid and (meth)acrylic acid alkyl ester, or a combination thereof.

Examples of the amphiprotic binder may include an acrylated styrene-based rubber.

When the water-soluble binder is used as the negative electrode binder, a cellulose-based compound may be further used to provide viscosity. Examples of the cellulose-based compound may include one or more of carboxylmethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or alkali metal salts thereof. The alkali metal may be Na, K, and/or Li. The cellulose-based compound may be included in an amount of <NUM> to <NUM> parts by weight based on <NUM> parts by weight of the negative electrode active material.

The positive electrode of the lithium secondary battery according to an embodiment of the present disclosure may include a positive electrode active material layer including a first positive electrode active material including at least one composite oxide of lithium and a metal of cobalt, manganese, nickel, or a combination thereof, and a second positive electrode active material including a compound represented by the Chemical Formula (<NUM>).

The lithium secondary battery according to an embodiment of the present disclosure may include both of the negative electrode function layer positioned on the negative electrode and the positive electrode active material layer including the first positive electrode active material and the second positive electrode active material, thereby reducing thermal runaway due to thermal/physical impacts and assisting the flake-shaped polyethylene particles in being melted to shut down (or perfectly shut down) ion passages. In a secondary battery not including the positive electrode according to an embodiment of the present disclosure, the ion passages may not be perfectly shut down during thermal runaway due to thermal/physical impacts (see <FIG>). However, in a secondary battery including both of the negative electrode including the negative electrode function layer and the positive electrode according to an embodiment of the present disclosure, the ion passages can be shut down (or perfectly shut down) during thermal runaway due to thermal/physical impacts, thereby obtaining a safety maximizing or increasing effect (see <FIG>).

Meanwhile, the positive electrode 125b may include a positive electrode current collector and a positive electrode active material layer positioned on the positive electrode current collector.

The positive electrode active material layer may include the first positive electrode active material including at least one composite oxide of lithium and a metal of cobalt, manganese, nickel, or a combination thereof, and the second positive electrode active material including a compound represented by the Chemical Formula (<NUM>).

wherein <NUM> ≤ a ≤ <NUM>, <NUM> ≤ x ≤ <NUM>, and M is Mg, Co, Ni or combinations thereof.

In addition, the positive electrode active material layer may further include a positive electrode function layer positioned on the positive electrode active material layer.

The first positive electrode active material may be at least one composite oxide of lithium and a metal of cobalt, manganese, nickel, or a combination thereof. Examples of the first positive electrode active material may include a compound represented by one of the following Chemical Formulas:.

LiaA<NUM>-bXbD<NUM> (<NUM> ≤ a ≤ <NUM>, <NUM> ≤ b ≤ <NUM>); LiaA<NUM>-bXbO<NUM>-cDc (<NUM> ≤ a ≤ <NUM>, <NUM> ≤ b ≤ <NUM>, <NUM> ≤ c ≤ <NUM>); LiaE<NUM>-bXbO<NUM>-cDc (<NUM> ≤ a ≤ <NUM>, <NUM> ≤ b ≤ <NUM>, <NUM> ≤ c ≤ <NUM>); LiaE<NUM>-bXbO<NUM>-cDc (<NUM> ≤ a ≤ <NUM>, <NUM> ≤ b ≤ <NUM>, <NUM> ≤ c ≤ <NUM>); LiaNi<NUM>-b-cCObXcDα (<NUM> ≤ a ≤ <NUM>, <NUM> ≤ b ≤ <NUM>, <NUM> ≤ c ≤ <NUM>, <NUM> < a ≤ <NUM>); LiaNi<NUM>-b-cCObXcO<NUM>-αTα (<NUM> ≤ a ≤ <NUM>, <NUM> ≤ b ≤ <NUM>, <NUM> ≤ c ≤ <NUM>, <NUM> < α < <NUM>); LiaNi<NUM>-b-cCobXcO<NUM>-αT<NUM> (<NUM> ≤ a ≤ <NUM>, <NUM> ≤ b ≤ <NUM>, <NUM> ≤ c ≤ <NUM><NUM> <α < <NUM>); LiaNi<NUM>-b-cMnbXcDα (<NUM> ≤ a ≤ <NUM>, <NUM> ≤ b ≤ <NUM>, <NUM> ≤ c ≤ <NUM>, <NUM> < α ≤ <NUM>); LiaNi<NUM>-b-cMnbXcO<NUM>-αTα (<NUM> ≤ a ≤ <NUM>, <NUM> ≤ b ≤ <NUM>, <NUM> ≤ c ≤ <NUM>, <NUM> < α < <NUM>); LiaNi<NUM>-b-cMnbXcO<NUM>-αT<NUM> (<NUM> ≤a ≤ <NUM>, <NUM> ≤ b ≤ <NUM>, <NUM> ≤ c ≤<NUM>, <NUM> < α < <NUM>); LiaNibEcGdO<NUM> (<NUM> ≤ a ≤ <NUM>, <NUM> ≤ b ≤ <NUM>, <NUM> ≤ c ≤ <NUM>, <NUM> ≤ d ≤ <NUM>); LiaNibCocMndGeO<NUM> (<NUM> ≤ a ≤ <NUM>, <NUM> ≤ b ≤ <NUM>, <NUM> ≤ c ≤ <NUM>, <NUM> ≤ d ≤ <NUM>, <NUM> ≤ e ≤ <NUM>); LiaNiGbO<NUM> (<NUM> ≤ a ≤ <NUM>, <NUM> ≤ b ≤ <NUM>); LiaCoGbO<NUM> (<NUM> ≤ a ≤ <NUM>, <NUM> ≤ b ≤ <NUM>); LiaMn<NUM>-bGbO<NUM> (<NUM> ≤ a ≤ <NUM>, <NUM> ≤ b ≤ <NUM>); LiaMn<NUM>GbO<NUM> (<NUM> ≤ a ≤ <NUM>, <NUM> ≤ b ≤ <NUM>); LiaMn<NUM>-gGgPO<NUM> (<NUM> ≤ a ≤ <NUM>, <NUM> ≤ g ≤ <NUM>); QO<NUM>; QS<NUM>; LiQS<NUM>; V<NUM>O<NUM>; LiV<NUM>O<NUM>; LiZO<NUM>; LiNiVO<NUM>; Li(<NUM>-f)J<NUM>(PO<NUM>)<NUM> (<NUM> ≤ f ≤ <NUM>); Li(<NUM>-f)Fe<NUM>(PO<NUM>)<NUM> (<NUM> ≤ f ≤ <NUM>); and LiaFePO<NUM> (<NUM> ≤ a ≤ <NUM>).

In the above chemical formulae, A is selected from the group consisting of Ni, Co, Mn, and a combination thereof; X is selected from the group consisting of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, and a combination thereof; D is selected from the group consisting of O, F, S, P, and a combination thereof; E is selected from the group consisting of Co, Mn, and a combination thereof; T is selected from the group consisting of F, S, P, and a combination thereof; G is selected from the group consisting of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and a combination thereof; Q is selected from the group consisting of Ti, Mo, Mn, and a combination thereof; Z is selected from the group consisting of Cr, V, Fe, Sc, Y, and a combination thereof; and J is selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, and a combination thereof.

Here, the compounds may have a coating layer on the surface, or may be mixed with another compound having a coating layer. The coating layer may include at least one coating element compound selected from the group of an oxide of the coating element, a hydroxide of the coating element, an oxyhydroxide of the coating element, an oxycarbonate of the coating element, and a hydroxyl carbonate of the coating element. The compound for the coating layer may be amorphous or crystalline. The coating element included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The coating layer may be formed by any suitable coating method (for example, spray coating or dipping) that demonstrates no adverse influence (or substantially no adverse influence) on properties of the positive electrode active material by using these elements in the compound, which will be well understood by one skilled in the art and further description thereof is not necessary here.

In an embodiment, the first positive electrode active material and the second positive electrode active material may be included in a weight ratio in a range from <NUM>:<NUM> to <NUM>:<NUM>, for example, <NUM>:<NUM> to <NUM>:<NUM>.

The first positive electrode active material may be included in an amount in a range from <NUM> wt % to <NUM> wt % based on the total weight of the positive electrode active material layer, for example, <NUM> wt% to <NUM> wt%, <NUM> wt% to <NUM> wt%, or <NUM> wt% to <NUM> wt%. When the amount of the first positive electrode active material satisfies the range, the safety can be improved without a reduction in the capacity.

The second positive electrode active material may include, for example, LiFePO<NUM>.

The second positive electrode active material may be included in an amount in a range from <NUM> wt % to <NUM> wt% based on the total weight of the positive electrode active material layer, for example, <NUM> wt% to <NUM> wt%, <NUM> wt% to <NUM> wt%, or <NUM> wt% to <NUM> wt%. When the amount of the second positive electrode active material satisfies the range, the safety can be improved without a reduction in the capacity.

Usable examples of the positive electrode current collector may include, but are not limited to, aluminium and nickel.

Optionally, the positive electrode active material layer may further include a positive electrode conductive material and a positive electrode binder.

Each of the positive electrode conductive material and the positive electrode binder may be included in an amount in a range from <NUM> wt% to <NUM> wt% based on the total weight of the positive electrode active material layer.

The positive electrode conductive material may be used to provide the positive electrode with conductivity (e.g., electrical conductivity), and kinds of the positive electrode conductive material are the same as those of the negative electrode conductive material.

The positive electrode binder may serve to improve binding properties of the positive active material particles with one another and with a current collector, and examples of the positive electrode binder may include, but are not limited to, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinylchloride, carboxylated polyvinylchloride, polyvinylfluoride, an ethylene oxide-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, and nylon.

The electrolyte includes a non-aqueous organic solvent and a lithium salt.

Examples of the non-aqueous organic solvent may include a carbonate-based, ester-based, ether-based, ketone-based, alcohol-based, or aprotic solvent. Examples of the carbonate-based solvent may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and the like. Examples of the ester-based solvent may include methyl acetate, ethyl acetate, n-propyl acetate, methylpropionate, ethylpropionate, γ-butyrolactone, decanolide, valerolactone, mevalonolactone, caprolactone and the like. Examples of the ether-based solvent may include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, <NUM>-methyltetrahydrofuran, tetrahydrofuran, and the like. Examples of the ketone-based solvent may include cyclohexanone, and the like. In addition, examples of the alcohol-based solvent may include ethyl alcohol, isopropyl alcohol, and the like, and examples of the aprotic solvent may include nitriles, such as R-CN (wherein R is a C2 to C20 linear, branched, or cyclic hydrocarbon group, or includes a double bond, an aromatic ring, or an ether bond), amides, such as dimethylformamide, dioxolanes, such as <NUM>,<NUM>-dioxolane, or sulfolanes.

The non-aqueous organic solvent may be used alone or in a mixture of more than one material. When the non-aqueous organic solvent is used in a mixture, the mixture ratio can be controlled in accordance with desirable battery performance and can be any suitable mixture ratio generally used in the art.

In addition, the carbonate-based solvent may be used by mixing a cyclic carbonate and a chain-type carbonate. In this case, when the cyclic carbonate and the chain-type carbonate are mixed together to a volume ratio in a range from <NUM>:<NUM> to <NUM>:<NUM>, excellent performance of the electrolyte may be demonstrated.

The aromatic hydrocarbon-based organic solvent may be an aromatic hydrocarbon-based compound represented by the following Chemical Formula (<NUM>):
<CHM>
wherein R1 to R6 are the same or different and are selected from the group consisting of a hydrogen, a halogen, a C1 to C10 alkyl group, a C1 to C10 haloalkyl group, and a combination thereof.

Examples of the aromatic hydrocarbon-based organic solvent may be selected from the group consisting of benzene, fluorobenzene, <NUM>,<NUM>-difluorobenzene, <NUM>,<NUM>-difluorobenzene, <NUM>,<NUM>-difluorobenzene, <NUM>,<NUM>,<NUM>-trifluorobenzene, <NUM>,<NUM>,<NUM>-trifluorobenzene, chlorobenzene, <NUM>,<NUM>-dichlorobenzene, <NUM>,<NUM>-dichlorobenzene, <NUM>,<NUM>-dichlorobenzene, <NUM>,<NUM>,<NUM>-trichlorobenzene, <NUM>,<NUM>,<NUM>-trichlorobenzene, iodobenzene, <NUM>,<NUM>-diiodobenzene, <NUM>,<NUM>-diiodobenzene, <NUM>,<NUM>-diiodobenzene, <NUM>,<NUM>,<NUM>-triiodobenzene, <NUM>,<NUM>,<NUM>-triiodobenzene, toluene, fluorotoluene, <NUM>,<NUM>-difluorotoluene, <NUM>,<NUM>-difluorotoluene, <NUM>,<NUM>-difluorotoluene, <NUM>,<NUM>,<NUM>-trifluorotoluene, <NUM>,<NUM>,<NUM>-trifluorotoluene, chlorotoluene, <NUM>,<NUM>-dichlorotoluene, <NUM>,<NUM>-dichlorotoluene, <NUM>,<NUM>-dichlorotoluene, <NUM>,<NUM>,<NUM>-trichlorotoluene, <NUM>,<NUM>,<NUM>-trichlorotoluene, iodotoluene, <NUM>,<NUM>-diiodotoluene, <NUM>,<NUM>-diiodotoluene, <NUM>,<NUM>-diiodotoluene, <NUM>,<NUM>,<NUM>-triiodotoluene, <NUM>,<NUM>,<NUM>-triiodotoluene, xylene, and a combination thereof.

In order to improve the cycle life of a battery, the non-aqueous electrolyte may further include vinylene carbonate or an ethylene carbonate-based compound represented by the following Chemical Formula (<NUM>):
<CHM>
wherein R<NUM> and R<NUM> are the same or different and are selected from the group consisting of a hydrogen, a halogen group, a cyano group (CN), a nitro group (NO<NUM>) and a fluorinated C1 to C5 alkyl group, wherein at least one of the R<NUM> and R<NUM> is a halogen group, a cyano group (CN), a nitro group (NO<NUM>), or a fluorinated C1 to C5 alkyl group, but both of R<NUM> and R<NUM> are not necessarily hydrogens.

Representative examples of the ethylene carbonate-based compound may include difluoro ethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylenecarbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylenecarbonate, fluoroethylene carbonate, and the like. When an additive for improving the cycle life is additionally used, the amount of the additive may be suitably or appropriately controlled.

The lithium salt dissolved in the organic solvent functions as a supply source of lithium ions in the battery to enable a basic operation of a rechargeable lithium battery and promotes movement of lithium ions between positive and negative electrodes. Examples of the lithium salt may include as a supporting salt one or more selected from LiPF<NUM>, LiBF<NUM>, LiSbF<NUM>, LiAsF<NUM>, LiN(SO<NUM>C<NUM>F<NUM>)<NUM>, Li(CF<NUM>SO<NUM>)<NUM>N, LiN(SO<NUM>C<NUM>F<NUM>)<NUM>, LiC<NUM>F<NUM>SO<NUM>, LiCIO<NUM>, LiAlO<NUM>, LiAlCl<NUM>, LiN(CxF2x+<NUM>SO<NUM>)(CyF2y+<NUM>SO<NUM>) where x and y are natural numbers, LiCl, Lil and LiB(C<NUM>O<NUM>)<NUM>, and lithium bis(oxalato) borate (LiBOB). The lithium salt may be used at a concentration in a range from <NUM> to <NUM>, and in one embodiment, at a concentration in a range from <NUM> to <NUM>. When the lithium salt is included at the above concentration range, the electrolyte may demonstrate suitable or appropriate conductivity and viscosity, thereby enhancing lithium ion mobility.

As described above, the separator 125c may be positioned between the positive electrode 125b and the negative electrode 125a. The separator 125c may be made of, for example, one selected from a glass fiber, polyester, polyethylene, polypropylene, polytetrafluoroethylene and a combination thereof, and may be a non-woven or woven material.

The separator made of, for example, a polyolefin-based polymer, such as polyethylene or polypropylene, may be mainly used for a lithium secondary battery. In order to obtain heat resistance or mechanical strength, a separator coated with a composition including a ceramic component or a polymeric material, may be used and, optionally, may have a single-layered structure or a multi-layered structure.

The following examples illustrate aspects of the present disclosure in more detail. These examples, however, are provided only for illustrative purposes but are not intended to limit the scope of the appended claims.

A positive electrode active material slurry was prepared by mixing <NUM> wt% of a positive electrode active material having LiCoO<NUM>/LiFePO<NUM> (LCO/LFP) mixed to a weight ratio of <NUM>:<NUM>, <NUM> wt% of polyvinylidenfluoride as a binder, and <NUM> wt% ketjen black as a conductive material in N-methylpyrrolidone as a solvent. The positive electrode active material slurry was coated on both surfaces of an Al current collector, dried and pressed to provide a positive electrode (cathode) including a positive electrode active material layer.

A negative electrode active material slurry was prepared by mixing <NUM> wt% of graphite, <NUM> wt% of carboxymethyl cellulose and <NUM> wt% of styrene-butadiene rubber in pure water. The negative electrode active material slurry was coated on both surfaces of a Cu current collector, dried and pressed to provide a negative electrode (anode) including a negative electrode active material layer.

<NUM> wt% of flake-shaped PE particles having an average particle size of <NUM> (Major axis length/Minor axis length= about <NUM>, thickness= about <NUM>), <NUM> wt% of alumina (Average particle diameter (D50)= <NUM>) and <NUM> wt% of acrylated styrene-based rubber as a binder were mixed in an alcohol-based solvent to prepare a PE/alumina slurry.

The PE/alumina slurry was coated on the surface of the negative electrode, dried and pressed to provide a coated negative electrode including a coating layer including flake-shaped PE particles.

The positive electrode, the separator including a PE/PP multi-layered substrate, and the negative electrode including the coating layer including the flake-shaped PE particles were sequentially stacked to fabricate an electrode assembly shown in <FIG> and <FIG>, followed by injecting an electrolyte, thereby fabricating a secondary battery.

A secondary battery was fabricated in substantially the same manner as in Example <NUM>, except that a negative electrode was provided using flake-shaped PE particles having an average particle size of <NUM> (Major axis length/Minor axis length= about <NUM>, thickness= about <NUM>).

A secondary battery was fabricated in substantially the same manner as in Example <NUM>, except that a negative electrode was provided using a dispersion liquid prepared by dispersing spherical PE particles having an average particle size of <NUM>, instead of <NUM> flake-shaped PE particles, in an alcohol-based solvent.

A negative electrode (anode) including a coating layer including the flake-shaped PE particles according to Example <NUM>, a separator including a PE/PP multi-layered substrate, and a negative electrode including a coating layer including the flake-shaped PE particles according to Example <NUM>, were sequentially stacked in that order, followed by injecting an electrolyte prepared by dissolving <NUM> LiBF<NUM> in propylene carbonate (PC), thereby fabricating a symmetrical coin-type battery shown in <FIG>.

<FIG> is a diagram showing symmetrical coin-type batteries fabricated for evaluating resistance increase rates of electrode plates.

A temperature sensor and a resistance meter were installed on the fabricated symmetrical coin-type battery, and the battery was inserted into a temperature-varying chamber for evaluation. Changes in temperatures and resistances of the symmetrical coin-type battery were evaluated while increasing the temperature at a rate of <NUM>/min, and increase rate evaluation results of AC resistance (ACR) (ohm) of electrode plates depending on the temperature is shown in <FIG>.

<FIG> is a graph showing ACR increase rate evaluation results of electrode plates depending on temperatures.

As confirmed from <FIG>, AC resistance (ACR) increase rates of electrode plates in Examples <NUM> to <NUM> were remarkably increased at a high temperature of <NUM> or higher, compared to the ACR increase rate of an electrode plate in the Comparative Example.

From the evaluation results, in the battery cell including the electrode composition according to an embodiment, ion passages can be effectively shut down during thermal runaway due to thermal/physical impacts. Therefore, it can be expected for a shut-down function to be manifested quickly.

Lithium secondary batteries fabricated in Examples <NUM> to <NUM> were charged at a charge potential of <NUM> V at <NUM>. 5C rates and then discharged to reach <NUM> V. After <NUM> cycles, cell capacity decrease rates were measured, and the results are shown in <FIG>. At the 51st and 101st cycles, the battery cells were charged at a charge potential of <NUM> V at <NUM>. 5C and then discharged to reach <NUM> V. Then, capacity retentions were measured to evaluate capacity recovery.

<FIG> is a graph showing capacity retention evaluation results of lithium secondary batteries according to Examples <NUM> to <NUM> for <NUM> cycles.

Referring to <FIG>, even after <NUM> cycles, it was confirmed that excellent capacity retention ratios (%) were demonstrated.

As a result, the lithium secondary battery according to an embodiment of the present disclosure can effectively demonstrate a shut-down function while maintaining excellent battery characteristics.

Claim 1:
An energy storage module (<NUM>, <NUM>) comprising:
a plurality of battery cells (<NUM>) arranged in a first direction such that long side surfaces of adjacent ones of the battery cells (<NUM>) face one another, each of the battery cells (<NUM>) comprising a vent (124a);
a plurality of insulation spacers (<NUM>, <NUM>), at least one of the insulation spacers (<NUM>, <NUM>) being between the long side surfaces of each adjacent pair of the battery cells (<NUM>), each of the insulation spacers (<NUM>, <NUM>) comprising a heat-insulating first sheet (131a, 231a) and a plurality of flame-retardant second sheets (131b, 231b) respectively adhered to opposite surfaces of the first sheet (131a, 231a) by an adhesion member (131c, 231c);
a cover member (<NUM>, <NUM>) comprising an internal receiving space configured to accommodate the battery cells (<NUM>) and the insulation spacers (<NUM>, <NUM>);
a top plate (<NUM>, <NUM>) coupled to a top of the cover member (<NUM>, <NUM>), the top plate (<NUM>, <NUM>) comprising ducts (<NUM>, <NUM>) respectively corresponding to the vents (124a) of the battery cells (<NUM>) and having fire extinguishing agent openings (<NUM>, <NUM>) respectively corresponding to the insulation spacers (<NUM>, <NUM>);
a top cover (<NUM>, <NUM>) coupled to a top of the top plate (<NUM>, <NUM>) and having discharge openings (<NUM>, <NUM>) respectively corresponding to the ducts (<NUM>, <NUM>); and
an extinguisher sheet (<NUM>, <NUM>) between the top cover (<NUM>, <NUM>) and the top plate (<NUM>, <NUM>), the extinguisher sheet (<NUM>, <NUM>) being configured to emit a fire extinguishing agent at a temperature exceeding a reference temperature, and
wherein the long side surfaces of adjacent ones of the battery cells (<NUM>) are spaced apart from each other by a first distance, and
wherein a thickness of each of the insulation spacers (<NUM>, <NUM>) is less than <NUM>% of the first distance.