Patent Description:
The present invention relates to a cylindrical rechargeable battery including a piezoelectric element and a thermoelectric element.

Recently, there has been a growing interest in rising prices of energy sources caused by depletion of fossil fuels as well as environmental pollution, and a demand for environmentally-friendly alternative energy sources has become an indispensable factor for future life. Accordingly, research on various electric power production technologies such as atomic power, solar power, wind power, tidal power, etc. continues, and electric power storage devices for more efficient use of the generated energy are also drawing attention.

Moreover, as technology development and demand for mobile devices and battery cars increases, the demand for batteries as energy sources is rapidly increasing, and accordingly, many studies on batteries capable of meeting various demands have been conducted. In particular, in terms of materials, there is a high demand for lithium rechargeable batteries such as lithium ion batteries, lithium ion polymer batteries, and the like which have advantages such as high energy density, discharge voltage, and output stability.

Such rechargeable batteries are classified depending on a structure of an electrode assembly in which a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode are stacked. Representative examples thereof may include a jelly-roll type (wound-type) of electrode assembly in which a positive electrode and a negative electrode having a long sheet-like shape are wound with a separator interposed therebetween, a stacked type of electrode assembly in which a plurality of positive electrodes and negative electrodes that are cut in a predetermined size unit are sequentially stacked with separators interposed therebetween, and the like. Recently, a stack/folding type of electrode assembly in which unit cells obtained by stacking positive and negative electrodes of a predetermined unit with separators interposed therebetween, which are disposed on a separation film, are sequentially wound has been developed as an electrode assembly having an advanced structure in which the jelly-roll type and the stack type are mixed in order to solve problems of the jelly-roll types and the stack types of electrode assemblies.

Such electrode assemblies are accommodated in a pouch case, a cylindrical can, a rectangular case, or the like depending on the purpose of use, to manufacture batteries.

Among them, the cylindrical battery has the advantages of easy manufacturing and high energy density per unit weight, and is used as an energy source of various devices ranging from portable computers to battery cars. A content of silicon is increased in a negative electrode active material in order to maximize a high energy density advantage. In this case, silicon has large volume expansion during charge and discharge of the battery, which causes a lot of stress in the battery during repeated volume expansion of the negative electrode. Graphite has a relatively small volume expansion compared to silicon, but it also causes volume expansion and stress. In particular, there is a problem that the stress is concentrated in a stepped portion of the two electrodes.

<CIT>, which is a document published later than the priority date of this application, discloses a thermoelectric element which is integrated in a tab of a cylindrical battery, and a piezoelectric element is integrated in a cap of the battery.

<CIT> discloses a lithium secondary battery with a rubber member comprising a PTC device. The PTC device is capable of shutting off the battery when the internal temperature is between <NUM> and <NUM>.

In addition, in the case of a high density and high capacity battery, such as a cylindrical battery, there is a problem that a lot of heat energy is generated in the charging and discharging process and it is required to control it effectively.

Therefore, there is a need for a technique that can fundamentally solve this problem.

An object of the present invention is to solve the problems of the prior art and technical problems from the past.

The inventors of the present application confirmed that a stress generated by the expansion of the negative electrode may be converted into electrical energy to control thermal energy using the electrical energy, by installing a piezoelectric element and a thermoelectric element in the positive electrode tab, thereby completing the present invention.

A cylindrical rechargeable battery according to the present invention for achieving this purpose includes a positive electrode, a negative electrode, and a separator, the positive electrode includes a positive electrode tab, and a piezoelectric element and a thermoelectric element are formed at edges of the positive electrode tab.

The positive electrode tab may have a rectangular strip shape having a long length in comparison with a width.

The piezoelectric element and the thermoelectric element may be formed at opposite edges of the positive electrode tab in a longitudinal direction thereof.

Accommodating spaces in which the piezoelectric element and the thermoelectric element are mounted may be formed at the edges.

The accommodating spaces may have a stepped shape.

Only the piezoelectric element may be formed at the edges.

The thermoelectric element may be formed at a central portion of the positive electrode tab.

An indentation may be formed to have a structure indented into the positive electrode tab.

The thermoelectric element may be accommodated in the indentation.

The electrical energy generated by the piezoelectric element may be transferred to the thermoelectric element through the positive electrode tab.

Two or more of the positive electrode tabs may be formed in the positive electrode.

The negative electrode is manufactured by applying and drying a negative electrode active material on a negative electrode current collector, and optionally, additional components may be further included.

The negative electrode collector is typically formed to have a thickness of <NUM> to <NUM>. Such a negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, or copper or stainless steel, a surface of which is treated with the carbon, nickel, titanium, silver, aluminum-cadmium alloy, or the like, may be used. In addition, like the positive electrode current collector, fine concavities and convexities may be formed on a surface of the negative electrode current collector to enhance the bonding strength of the negative electrode active material, and it may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.

For example, carbon such as hardly graphitized carbon and graphite-type carbon; a metal composite oxide such as LixFe<NUM>O<NUM> (<NUM>≤x≤<NUM>), LixWO<NUM> (<NUM>≤x≤<NUM>), SnxMe<NUM>-xMe'yOz (Me: Mn, Fe, Pb, and Ge; Me': Al, B, P, Si, Group <NUM>, Group <NUM>, and Group <NUM> elements of the periodic table, and halogen; <NUM> <x≤<NUM>; <NUM>≤y≤<NUM>; <NUM>≤z≤<NUM>); a lithium metal; a lithium alloy; a silicon-based alloy or a tin-based alloy; a metal oxide such as SnO, SnO<NUM>, PbO, PbO<NUM>, Pb<NUM>O<NUM>, Pb<NUM>O<NUM>, Sb<NUM>O<NUM>, Sb<NUM>O<NUM>, Sb<NUM>O<NUM>, GeO, GeO<NUM>, Bi<NUM>O<NUM>, Bi<NUM>O<NUM>, and Bi<NUM>O<NUM>; a conductive polymer such as polyacetylene; a Li-Co-Ni based material; and the like may be used as the negative electrode active material.

The negative electrode active material may contain <NUM> % or less of silicon.

The negative electrode may include a negative electrode tab, and the piezoelectric element and the thermoelectric element may be formed at edges of the negative electrode tab.

The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown.

In addition, throughout the specification, when referred to as "cross-section", it indicates when a cross-section which cuts a target part vertically is seen from the side.

In addition, throughout the specification, when referred to as "top view", it indicates when a target portion is viewed from above.

Further, since a structure and an operating principle of the "piezoelectric element" and the "thermoelectric element" are known techniques, a description thereof will be omitted.

<FIG> illustrates a plan view of a cylindrical rechargeable battery in which a piezoelectric element and a thermoelectric element are formed at a positive electrode tab thereof according to an exemplary embodiment of the present invention. <FIG> illustrates a cross-sectional view taken along a dotted line C of <FIG>.

Referring to <FIG> and <FIG>, a piezoelectric element <NUM> and a thermoelectric element <NUM> are formed at edges A and B of a positive electrode tab <NUM> of a cylindrical rechargeable battery <NUM>. For convenience of explanation, <FIG> illustrates an enlarged view of a portion where the positive electrode tab <NUM> is formed at an uncoated portion <NUM> of a positive electrode <NUM> before the positive electrode <NUM> and a negative electrode (not illustrated) are wound with the separator interposed therebetween.

The positive electrode tab <NUM> may have a rectangular strip shape having a long length in comparison with a width. The piezoelectric element <NUM> and the thermoelectric element <NUM> may be formed at opposite edges A and B in a longitudinal direction. As described above, the edges A and B are portions where stresses generated by repeated expansion of the negative electrode (not illustrated) are concentrated during charging and discharging of the cylindrical rechargeable battery <NUM>. This stress may be converted into battery energy through the piezoelectric element <NUM>. In addition, the battery energy operates the thermoelectric element <NUM> to absorb thermal energy generated in the cylindrical rechargeable battery <NUM> during the charge and discharge process. The electrical energy produced by the piezoelectric element <NUM> may be transferred to the thermoelectric element <NUM> through various paths. For example, the electrical energy may be transferred through a metal connector (not illustrated) electrically connecting to the piezoelectric element <NUM> and the thermoelectric element <NUM>. Meanwhile, in the exemplary embodiments illustrated in <FIG>, the electrical energy generated by the piezoelectric element <NUM> is transferred to the thermoelectric element <NUM> through the positive electrode tab <NUM>.

In particular, a portion where the positive electrode tab <NUM> is formed is a portion where a lot of thermal energy is intensively generated by a rapid flow of current in the charging and discharging process of the cylindrical rechargeable battery <NUM>. This thermal energy is absorbed and controlled by the thermoelectric element <NUM>.

<FIG> illustrates a top plan view according to another exemplary embodiment of the present invention. <FIG> illustrates a cross-sectional view taken along a dotted line C of <FIG>. <FIG> illustrates a cross-sectional view of an electrode tab
taken along the dotted line C of <FIG>.

Referring to <FIG>, accommodating spaces <NUM> and <NUM> in which the piezoelectric element <NUM> and the thermoelectric element <NUM> are mounted are formed at opposite edges A and B of the positive electrode tab <NUM> of a cylindrical rechargeable battery <NUM>. A form of the accommodating spaces <NUM> and <NUM> is not particularly limited, but as an example, it may be formed in the form of a step. An entire part or a portion of the piezoelectric element <NUM> is formed in the accommodating space <NUM> of the edge A. An entire part or a portion of the thermoelectric element <NUM> is formed in the accommodating space <NUM> of the edge B.

Through this structure, the piezoelectric element <NUM> and the thermoelectric element <NUM> of various shapes and volumes may be applied to the positive electrode tab <NUM>, and the piezoelectric element <NUM> and the thermoelectric element <NUM> may be prevented from escaping from the positive electrode tab <NUM> by a stress generated in a direction D during the charge and discharge process. Herein, the direction D indicates a direction perpendicular to a longitudinal direction of the positive electrode tab <NUM> in a direction parallel to a surface where the positive electrode <NUM> is formed with respect to the ground.

<FIG> illustrates a top plan view according to another exemplary embodiment of the present invention. <FIG> illustrates a cross-sectional view of an electrode tab taken along the dotted line C of <FIG>.

Referring to <FIG> and <FIG>, the piezoelectric element <NUM> is formed at edges A and B of the positive electrode tab <NUM> of a cylindrical rechargeable battery <NUM>, and the thermoelectric element <NUM> is formed at a central portion of the positive electrode tab <NUM>.

As described above, the edges A and B are portions where stresses generated by repeated expansion of the negative electrode (not illustrated) are concentrated during charging and discharging of the cylindrical rechargeable battery <NUM>. Therefore, only the piezoelectric element <NUM> is installed at the edges A and B to secure more battery energy. In addition, it is possible to easily control the high thermal energy generated in the cylindrical rechargeable battery <NUM> of high capacity and high output by operating the thermoelectric element <NUM> with the battery energy.

The accommodating spaces <NUM> and <NUM> in which the piezoelectric element <NUM> is mounted are formed at opposite edges A and B of the positive electrode tab <NUM>. A form of the accommodating spaces <NUM> and <NUM> is not particularly limited, but as an example, they may be formed in the form of a step. An entire part or a portion of the piezoelectric element <NUM> may be formed in the accommodating spaces <NUM> and <NUM> of the edges A and B.

An indentation <NUM> in which the thermoelectric element <NUM> is accommodatable may be formed in a central portion of the positive electrode tab <NUM>. The indentation <NUM> may be formed to have a structure indented into the positive electrode tab <NUM>, and an entire part or a portion of the thermoelectric element <NUM> may be accommodated in the indentation <NUM>. Through this structure, the thermoelectric element <NUM> of various shapes and volumes may be applied to the positive electrode tab <NUM>. In addition, an area in which the thermoelectric element <NUM> contacts the positive electrode tab <NUM> may be maximized so that thermal energy generated in the positive electrode tab <NUM> may be quickly transferred to the thermoelectric element <NUM> to be cooled.

As a modified example, the piezoelectric element <NUM> and the thermoelectric element <NUM> described above may be equally applied to the negative electrode tab (not illustrated).

Those of ordinary skill in the field of the present invention will be able to make various applications and modifications within the scope of the present invention based on the contents.

Claim 1:
A cylindrical rechargeable battery (<NUM>) comprising
a positive electrode (<NUM>), a negative electrode, and a separator, wherein the positive electrode (<NUM>) includes a positive electrode tab (<NUM>), and a piezoelectric element (<NUM>) and a thermoelectric element (<NUM>) are formed at edges (A, B) of the positive electrode tab (<NUM>).