Patent Description:
Since the first commercialization, rechargeable lithium-ion batteries have been widely used in various portable electronic products as well as in large electric vehicles and energy storage grids.

Positive-electrode active materials of lithium-ion batteries usually include lithium cobalt oxides (LCO), lithium manganese oxides (LMO), lithium iron phosphates (LFP), lithium nickel cobalt aluminum oxides (NCA), lithium nickel cobalt manganese oxides (NMC), and the like. Lithium ions can be reversibly intercalated and deintercalated in the foregoing positive-electrode materials.

However, electrode active materials with better performance are still in need in the field.

<CIT> discloses a lithium ion battery and a positive electrode material thereof including a high nickel material and a coating layer. The teaching suggests mixing ammonium sulphate (NH4)<NUM>SO<NUM> with the core material (high nickel material), thereby forming a coating of the active electrode material. <CIT> discloses a positive-electrode active material including a composition with at least one of sulfur, phosphorus and fluorine (F) on the surface of a complex-oxide particle containing transition metal.

This invention provides a new electrode active material as defined in claim <NUM>. Preferred aspects are defined by the claims depending from claim <NUM>. The electrode active material of this disclosure is applied to a battery, where the battery shows a reduced direct current resistance (DCR) growth rate during cycling.

According to the invention the electrode active material includes:.

In some embodiments, a weight content of element S in the electrode active material is <NUM>-<NUM> ppm, for example, <NUM>-<NUM> ppm, <NUM>-<NUM> ppm, <NUM>-<NUM> ppm, <NUM>-<NUM> ppm, <NUM>-<NUM> ppm, <NUM>-<NUM> ppm, <NUM>-<NUM> ppm, <NUM>-<NUM> ppm or <NUM>-<NUM> ppm, and for example, <NUM>-<NUM> ppm.

According to the invention, the coating layer further includes one or more of element B, element P, and element F;.

In some embodiments, the lithium-containing compound includes a lithium salt; and
optionally, the lithium-containing compound includes one or more of the following: Li<NUM>O, LiOH and Li<NUM>CO<NUM>, LiNO<NUM>, LiPF<NUM>, lithium oxalate, lithium acetate, LiClO<NUM>, LiBF<NUM>, LiCF<NUM>SO<NUM>, LiAsF<NUM>, LiAlCl4, LiN(CF<NUM>SO<NUM>)<NUM> and LiC(SO<NUM>CF<NUM>)<NUM>.

In some embodiments, the sulfur-containing compound is an organic sulfur-containing compound.

In some embodiments, the sulfur-containing compound includes one or more of the following: mercaptan, thiophenol, thioether, thioaldehyde, thioketone, thiocarboxylic acid, sulfoxide, sulfone, sulfur oxoacid, and derivatives thereof.

In some embodiments, the sulfur-containing compound includes one or more of the following: thioether (such as straight-chain thioether or cyclic thioether), sulfoxide, sulfone, sulfur oxoacid (such as sulfonic acid, sulfinic acid, or sulfenic acid), and derivatives thereof.

In some embodiments, the sulfur-containing compound includes one or more of the following: sulfoxide, sulfone, sulfur oxoacid (such as sulfonic acid, sulfinic acid, or sulfenic acid), and derivatives thereof.

In some embodiments, derivatives of the sulfur oxoacid include one or more of the following: an ester of the sulfur oxoacid, a salt of the sulfur oxoacid (optionally, a lithium salt of the sulfur oxoacid), an acyl halide of the sulfur oxoacid, an amide of the sulfur oxoacid, and a lithium amide salt of the sulfur oxoacid.

In some embodiments, the sulfur oxoacid is an organic sulfur oxoacid.

In some embodiments, the sulfur oxoacid is sulfonic acid, sulfinic acid, or sulfenic acid.

In some embodiments, the sulfur-containing compound includes one or more of the following:
R1-S(=O)<NUM>-R2, R1-C(=S)-R2,
<CHM>
R1-C-S-C-R2, or R1-S(=O)<NUM>-LiN-S(=O)<NUM>-R2, where R1 and R2 each are selected from hydroxyl, amino, C<NUM>- <NUM> alkyl, aryl, a halogen atom (for example, F, Cl, Br, or I), and a hydrogen atom.

In some embodiments, the sulfur-containing compound includes R1-S(=O)<NUM>-R2, where R1 is hydroxyl, and R2 is selected from amino, C<NUM>-<NUM> alkyl, and the halogen atom (for example, F, Cl, Br, or I).

In some embodiments, the sulfur-containing compound includes R1-C(=O)<NUM>-R2, where R1 is amino, and R2 is C<NUM>-<NUM> alkyl.

In some embodiments, the sulfur-containing compound includes
<CHM>
where R1 and R2 each are a hydrogen atom or C<NUM>-<NUM> alkyl.

In some embodiments, the sulfur-containing compound includes R1-C-S-C-R2, where R1 and R2 each are a hydrogen atom or C<NUM>-<NUM> alkyl.

In some embodiments, the sulfur-containing compound includes R1-S(=O)<NUM>-LiN-S(=O)<NUM>-R2, where R1 and R2 each are a halogen atom.

In some embodiments, the sulfur-containing compound includes one or more of the following: sulfamide, aminomethanesulfonic acid, lithium bisfluorosulfonimide, thio-propionamide, thio-isobutyramide, propylene sulfide, and methyl ethyl sulfide.

According to the invention, the ternary material includes one or more of the following: lithium nickel cobalt manganese oxides and lithium nickel cobalt aluminum oxides;
optionally, a chemical formula of the lithium nickel cobalt manganese oxides is LixNiaCobMncM<NUM>(<NUM>-a-b-c)O<NUM>, where <NUM>≤x≤<NUM>, <NUM>≤a≤<NUM>, <NUM>≤b≤<NUM>, <NUM>≤c≤<NUM>, and M<NUM> is selected from a combination of one or more of Zr, Zn, Ti, Sr, Sb, Y, W, Al, B, P, and F.

In some embodiments, x=<NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, or <NUM>-<NUM>.

In some embodiments, a=<NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, or <NUM>-<NUM>.

In some embodiments, b=<NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, or <NUM>-<NUM>.

In some embodiments, c=<NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, or <NUM>-<NUM>.

Optionally, a chemical formula of the lithium nickel cobalt aluminum oxides is LixNidCoeAlfM<NUM>(<NUM>-d-e-f)O<NUM>, where <NUM>≤x≤<NUM>, <NUM>≤d≤<NUM>, <NUM>≤e≤<NUM>, <NUM>≤f≤<NUM>, and M<NUM> is selected from a combination of one or more of Zr, Mg, Ba, Ti, Sr, Sb, Y, W, and B.

In some embodiments, d=<NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, or <NUM>-<NUM>.

In some embodiments, e=<NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, or <NUM>-<NUM>.

In some embodiments, f=<NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>.

Unless otherwise specified, the coating layer mentioned in this disclosure is a coating layer that includes the reaction product of the sulfur-containing compound and the lithium-containing compound.

In some embodiments, a particle size (Dv<NUM> particle size) of the electrode active material is <NUM>-<NUM>, for example, <NUM>-<NUM>.

The invention further provides a preparation method of an electrode active material with a coating layer according to the steps as defined by claim <NUM>. Preferred embodiments are subject of the claims depending from claim <NUM>. The method includes:.

In some embodiments, in (a1), the lithium-containing compound is an alkaline lithium-containing compound.

In some embodiments, in (a2), the lithium-containing compound is a neutral lithium-containing compound or an acidic lithium-containing compound.

In some embodiments, the processing the core material by using the coating layer forming material includes: applying a solution containing the coating layer forming material to the surface of the core material, and performing heat treatment;.

In some embodiments, the applying a solution containing the coating layer forming material to the surface of the core material includes: dispersing the core material in the solution dissolved with the coating layer forming material, then separating the core material from the solution.

In some embodiments, in the solution containing the coating layer forming material, a concentration of the sulfur-containing compound is <NUM>-<NUM> mol/L (for example, <NUM>-<NUM> mol/L).

In some embodiments, in the solution containing the coating layer forming material, a concentration of the lithium-containing compound is <NUM>-<NUM> mol/L (for example, <NUM>-<NUM> mol/L).

In some embodiments, in the solution containing the coating layer forming material, a solvent includes one or more of the following substances: water, ethanol, and NMP, and optionally, the solvent is alcohol with a concentration of <NUM>-<NUM> vol%.

In some embodiments, the lithium-containing compound is as defined in any one of the foregoing embodiments.

In some embodiments, the sulfur-containing compound is as defined in any one of the foregoing embodiments.

In some embodiments, the ternary material is as defined in any one of the foregoing embodiments.

In some aspects, an electrode active material with a coating layer is provided and obtained by the preparation method according to any one of the foregoing embodiments.

In some aspects, an electrode is provided, including the electrode active material according to any one of the foregoing embodiments.

In some aspects, a battery is provided, including the electrode active material according to any one of the foregoing embodiments.

In some aspects, an apparatus is provided, including the battery according to any one of the foregoing embodiments, where the battery is used as an energy storage unit of the apparatus.

In some embodiments, the apparatus is an electric apparatus, and the battery is configured to power the electric apparatus.

In some embodiments, a method for preparing an electrode active material with a coating layer is a wet method.

In some aspects, an apparatus is provided, including the foregoing battery, where the battery is used as an energy storage unit of the apparatus.

In some embodiments, "comprising", "including", and "containing" may refer to a weight content greater than <NUM>, for example, above <NUM>%, above <NUM>%, above <NUM>%, above <NUM>%, above <NUM>%, above <NUM>%, above <NUM>%, above <NUM>%, above <NUM>%, above <NUM>%, and <NUM>%. When the percentage is <NUM>%, "comprising", "including", and "containing" means "consisting of".

For simplicity, only some numerical ranges are expressly disclosed in this specification. However, any lower limit may be combined with any upper limit to form a range not expressly recorded; any lower limit may be combined with any other lower limit to form a range not expressly recorded; and any upper limit may be combined with any other upper limit to form a range not expressly recorded. In addition, although not expressly recorded, each point or individual value between endpoints of a range is included in the range. Therefore, each site or single numerical value can be used as its own lower limit or upper limit in combination with any other site or single numerical value or in combination with other lower or upper limits to form a range not expressly recorded.

In the descriptions of this specification, it should be noted that "more than" or "less than" is inclusive of the present number and that "more" in "one or more" means two or more than two, unless otherwise specified.

The foregoing summary is not intended to describe each of the disclosed embodiments or implementations of this application. The following description illustrates exemplary embodiments in more detail by using examples. Throughout this application, guidance is provided by using a series of embodiments and the embodiments may be used in various combinations. In each example, enumeration is only representative but should not be interpreted as exhaustive.

Where the following terms are used in the present invention, they can be understood in the following non-limiting manner.

The "electrode active material" is a battery material with a specific composition and a crystal structure for intercalating and deintercalating lithium ions.

The "electrode" is a component that participates in an electrochemical reaction of the battery and that includes the electrode active material.

The "battery" is a single physical module that includes one or more battery cells for providing a higher voltage and capacity. The "battery cell" is a battery cell that can be charged and discharged independently. A cell structure includes a positive electrode, a negative electrode, a separator, an electrolyte, an outer package for packaging a positive-electrode plate, a negative-electrode plate, the separator, and the electrolyte, and the like. The type and shape of the battery cell are not specifically limited in this application. The battery cell may be a soft package battery cell, or may be a cylinder cell, a prismatic cell, or another type of cell.

The battery may include a battery cell, a battery module, and a battery pack. The battery module is formed by electrically connecting a specific quantity of battery cells and putting the battery cells into a frame to protect the battery cells from external impact, heat, vibration, and the like. The battery pack is a final state of a battery system assembled in an electric apparatus such as an electric vehicle. Most existing battery packs are formed by assembling various control and protection systems such as a battery management system and a thermal management part on one or more battery modules. With the development of technologies, the battery module may be omitted, that is, the battery pack is directly formed using battery cells. With this improvement, weight energy density and volumetric energy density of the battery system are improved, and the number of parts is remarkably reduced.

The "single crystal" is also referred to as a single particle or a primary particle, and in terms of micro morphology, the single crystal is a particle that substantially does not agglomerate or disperse. The single crystal may be a particle with an irregular shape.

The "polycrystal" is a secondary particle formed by agglomeration of more than two primary particles. The polycrystal may be a spherical particle.

The terms "powder" and "particle" may be used interchangeably in this specification. These terms further randomly have the following features: hollow, dense, porous, semiporous, coated, uncoated, multi-layer, laminated, simple, complex, dendritic, inorganic, organic, elemental, non-elemental, compound, doped, undoped, spherical, non-spherical, surface-functional, non-surface-functional, stoichiometric, and non-stoichiometric forms or substances. In addition, the term "powder" generally includes a one-dimensional material (fiber, tube, or the like), a two-dimensional material (a slice, a thin film, a laminated material, a flat surface, or the like), and a three-dimensional material (a sphere, a cone, an oval, a cylinder, a cube, a homocline, a dumbbell shape, a hexagon, a truncated icosahedron, an irregular structure, or the like).

The term "sphere" herein is a regular sphere, an ellipsoid, or a sphere-like shape.

The term "Dv10" herein is a volume-based particle size at the <NUM>-th percentile; the term "Dv<NUM>" is a volume-based particle size at the <NUM>-th percentile; and the term "Dv90" is a volume-based particle size at the <NUM>-th percentile. The particle size is measured by using a laser diffraction method.

The term "lithium salt" is a lithium-containing compound that can dissociate in a solvent to produce lithium ions.

The term "mercaptan" refers to replacement of alcoholic hydroxyl in an ethanol molecule with -SH.

The term "thiophenol" refers to replacement of a phenolic hydroxyl in a phenol molecule with -SH.

The term "thioether" is a compound with an R3-S-R4 structure, where R3 and R4 are each independently alkyl.

The term "thioaldehyde" refers to replacement of aldehyde C(O)H in an aldehyde molecule with C(S)H.

The term "thioketone" refers to replacement of carbonyl -C(O)- in a ketone molecule with -C(S)-.

The term "thiocarboxylic acid" refers to replacement of -COOH in a carboxylic acid molecule with CO-SH, CS-OH, or CSSH.

The term "sulfone" is a compound having a group -S(O)<NUM>R, where R is alkyl, aryl, or heteroaryl.

The term "sulfoxide" is a compound with a group -S(O)R, where R is alkyl, aryl, or heteroaryl.

The terms "sulfonic acid", "sulfinic acid", and "sulfenic acid" are compounds with -S(O)<NUM>OH, -S(O)OH, and -SOH respectively.

The term "amino" is unsubstituted or substituted amino. The substituted amino is, for example, alkyl-substituted amino, for example, methylamino.

The term "C<NUM>-<NUM> alkyl" refers to alkyl with <NUM> to <NUM> carbon atoms, and may be branched or straight-chain, saturated or unsaturated, and unsubstituted or mono/polysubstituted.

This disclosure provides an electrode active material with a coating layer, including a core and a coating layer, where the core includes a ternary material; and the coating layer coats the core, the coating layer includes a reaction product of a sulfur-containing compound and a lithium-containing compound, and the reaction product includes element Li, element S, and element O.

One or more technical solutions recorded in this disclosure have one or more of the following beneficial effects.

The following embodiments specifically describe an electrode active material with a coating layer and a preparation method thereof. A battery is assembled by using the electrode active material, and tested for one or more of the following performance: capacity retention rate, direct current resistance, gas production, and slurry processing performance.

The following embodiments describe in more detail content disclosed in this application. These embodiments are intended only for illustrative purposes because various modifications and changes made without departing from the scope of the content disclosed in this application are apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weights, all reagents used in the embodiments are commercially available or synthesized in a conventional manner, and can be used directly without further processing, and all instruments used in the embodiments are commercially available.

The electrode active material powder as a core material is a commercially available ternary material, specifically, NCMs <NUM>-<NUM> are lithium nickel cobalt manganese oxides and NCAis a lithium nickel cobalt aluminum oxide. Due to a preparation process, residual lithium is present on a surface of the core material. Relevant parameters of the core material are shown in the following table:
<IMG>.

Step <NUM>: providing the ternary material as a core material.

Step <NUM>: providing a solution containing a coating layer formation material, where a formula of the solution containing the coating layer formation material is shown in Table <NUM>.

Step <NUM>: mixing the products in step <NUM> and step <NUM> at a weight ratio of <NUM>:<NUM>, stirring for <NUM> minutes after the mixing, and upon solid-liquid separation, collecting solids.

Step <NUM>: performing heat treatment to the solids obtained in the previous step in an inert atmosphere in a closed environment to obtain an electrode active material with a coating layer, with heat treatment conditions shown in Table <NUM>.

In the foregoing example, an alkaline lithium-containing compound (such as Li<NUM>O, LiOH, and Li<NUM>CO<NUM>) was present on the surface of the core material, and the alkaline lithium-containing compound reacted with a sulfur-containing compound during a coating process, producing a reaction product of the sulfur-containing compound and the lithium-containing compound, where the reaction product included element Li, element S, and element O.

After the coating treatment was performed on the core material based on the foregoing method, an electrode active material with a coating layer was obtained. Specific process parameters are shown in Table <NUM>.

<NUM> samples are shown in Table <NUM>, including coated and uncoated electrode active materials. These <NUM> samples are tested by using the following test methods.

Preparation of a positive-electrode plate: At <NUM>% environmental humidity, the electrode active material prepared in the foregoing examples/comparative examples was mixed with conductive carbon black and a binder PVDF at a mass ratio of <NUM>:<NUM>:<NUM>. A solvent N-methylpyrrolidone (NMP) was added, with a mass of the solvent accounting for <NUM>% of a total weight of a slurry, to produce a uniform positive-electrode slurry after stirring. The positive-electrode slurry was evenly applied on both sides of a positive-electrode collector aluminum foil, the aluminum foil was cold pressed by using a roller press to obtain a positive-electrode plate, and a press density of the obtained positive-electrode plate was <NUM>-<NUM>/cc.

Preparation of a negative-electrode plate: Artificial graphite was used as a negative-electrode active substance. In a negative-electrode slurry, solid components were formed by the artificial graphite, styrene polybutadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), and conductive carbon black at a ratio of <NUM>:<NUM>:<NUM>:<NUM>. A solvent of the slurry was water, and the solvent accounted for <NUM>% of weight of the slurry. The negative-electrode slurry was evenly applied on both sides of a negative-electrode current collector copper foil, the copper foil was cold pressed by using a roller press to obtain a negative-electrode plate, and a press density of the negative-electrode plate was <NUM>/cc.

Separator: A PP/ PE composite separator was used.

Electrolyte: <NUM> mol/L of LiPF<NUM> solution was selected. Its solvent mainly includes ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC).

Assembly of a battery: The negative-electrode plate, the separator, and the positive-electrode plate were stacked and then wound. After a roll core was obtained, a tab was welded on the copper and aluminum foil current collectors of the positive-electrode plate and the negative-electrode plate exposed from the core, and all are encapsulated in a packaging bag made of aluminum-plastic composite material. A thickness of the packaging bag was <NUM>. An electrolyte was injected and then the bag was sealed. Chemical conversion was performed at <NUM>. After the chemical conversion, gas generated by the chemical conversion was extracted and excess packaging bags were removed to obtain a battery with a height of <NUM>, a thickness of <NUM>, and a width of <NUM>.

The battery was charged and discharged at a constant test room temperature (<NUM>) by using a Neware charge and discharge machine (5V/6A). A charging and discharging method was as follows:.

The battery was left standing for <NUM> minutes at a constant temperature of <NUM>. The battery was charged at a constant current rate of <NUM>. 33C to a charge cut-off voltage (charge cut-off voltages of battery cells corresponding to different active materials are shown in the following table) and then charged at a constant voltage of the charge cut-off voltage until a charge current was less than or equal to <NUM>.

The battery was left standing for <NUM> minutes;
<NUM>. The battery was discharged at a constant current rate of <NUM>. 33C to a discharge cut-off voltage (in the following examples, the discharge cut-off voltage is set to <NUM> V and may be adjusted based on different to-be-detected batteries);.

A first-cycle discharge specific capacity was determined as a test result.

The charge/discharge current was a preset rate multiplied by a rated capacity of the battery cell. The rated capacity is based on a cell capacity identified in a GBT certification document for the cell, or the battery module to which the cell belongs, or the battery pack to which the cell belongs.

A high/low temperature chamber of <NUM> from Tengda was used for testing. A charging and discharging method is as follows:.

After fully charged, the battery cell was stored in a high-temperature furnace at <NUM>. At regular intervals, the battery cell was taken out of the furnace and a volume of the battery was measured by using a drainage method. A volume change before and after the storage was found after comparison, and a volume change rate of the gas production was obtained.

During cycling, an average voltage/average current <NUM> seconds before charging to <NUM>% SOC is extracted for each cycle to obtain a DCR at a corresponding number of cycles. After DCRs are extracted by the number of cycles, a DCR growth rate during the cycling is obtained.

A laser particle size test was performed by using a Mastersizer 3000E laser particle size analyzer from Malvern instruments Ltd in UK. A test method can be referred to a <CIT> particle size distribution laser diffraction method. In the test, the electrode active material was dispersed in water to obtain a particle refractive index of <NUM>.

A method for testing a particle size of electrode active material in the finished electrode is as follows: powder was scraped from the positive-electrode plate, the scraped powder was collected, put in a sintering furnace, and sintered at <NUM> for <NUM> hours to remove conductive carbon and binder from the powder and obtain an electrode active material. A laser particle size test was performed on the electrode active material by using a Mastersizer 3000E laser particle size analyzer.

Test results obtained by testing samples <NUM>-<NUM> based on the foregoing methods are described in detail below.

<FIG> shows scanning electron microscope images of an electrode active material numbered <NUM>, with (a)-(d) sequentially showing images at scales of <NUM>, <NUM>, <NUM>, and <NUM>. Particles of the electrode active material have irregular particle shapes, with a single crystal micro-structure.

<FIG> shows scanning electron microscope images of an electrode active material numbered <NUM>, with (a)-(d) sequentially showing images at different magnifications or positions. (a)-(d) sequentially show images at scales of <NUM>, <NUM>, <NUM>, and <NUM>. Particles of the electrode active material have a spherical particle shape, with a polycrystal micro-structure.

Particle size distributions of the electrode active materials numbered <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are as follows:
<IMG>.

Contents of element S, element B, element P, and element F in the electrode active materials numbered <NUM>-<NUM> are as follows:.

Coating treatment is not performed on the electrode active materials numbered <NUM> to <NUM>, <NUM>, and <NUM>. Because a raw material precursor contains elemental sulfur, the electrode active materials inevitably contain trace amounts of residual element sulfur (<<NUM> ppm). Only exeamples <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> contain contents of element S, element B, element P, or element F in the electrode active materials numbered, therefore, only these examples fall under the definition of the claims. The remaining examples are not part of the invention.

The electrode active material numbered <NUM> was used to prepare a slurry in environment with a relative humidity of <NUM>% and <NUM>%, respectively, with the following formulation: the electrode active material, conductive carbon black, and a binder PVDF were mixed at a mass ratio of <NUM>:<NUM>:<NUM> A solvent N-methyl-pyrrolidone (NMP) was added, with a mass of the solvent accounting for <NUM>% of a total weight of the slurry, and a resulting mixture was stirred to form a uniform positive-electrode slurry. The slurries prepared in environment with two different humidity were left standing, and viscosities of the electrode slurries were analyzed at regular intervals by using a rheological analyzer (Gemini <NUM> Rheometer, Malvern Instruments ltd).

In addition, based on the foregoing testing method, the sample numbered <NUM> was also treated in the same way and taken as a reference group, and results are shown in the following table:
<IMG>.

The electrode active material numbered <NUM> was used to prepare a slurry in environment with a relative humidity of <NUM>% and <NUM>%, respectively, with the following formulation: the electrode active material, conductive carbon black, and a binder PVDF are mixed at a mass ratio of <NUM>:<NUM>:<NUM>. A solvent N-methyl-pyrrolidone (NMP) was added, with a mass of the solvent accounting for <NUM>% of a total weight of the slurry, and a resulting mixture was stirred to form a uniform positive-electrode slurry. The slurries prepared in environment with two different humidity were left standing, and viscosities of the electrode slurries were analyzed at regular intervals by using a rheological analyzer (Gemini <NUM> Rheometer, Malvern Instruments ltd).

In addition, based on the foregoing testing method, the sample numbered <NUM> was treated in the same way and taken as a reference group, and results are shown in the following table:
<IMG>.

From the foregoing experimental data, it can be learned that compared to the electrode active materials (No. <NUM> and <NUM>) without a coating layer, the electrode active materials (No. <NUM> and <NUM>) with a coating layer have improved processing performance. Specifically, the electrode active materials (No. <NUM> and <NUM>) with a coating layer have relatively low viscosity and no obvious gelation in appearance by visual observation, no matter whether the slurry is prepared at <NUM>% or <NUM>% relative humidity. Such a slurry is beneficial to subsequent processes of coating and cold pressing, and beneficial to improving electrical performance of the battery.

From the foregoing experimental data, it can be learned that a coating layer containing a reaction product of a lithium-containing compound and a sulfur-containing compound can improve performance of the electrode active material. Compared to the electrode active materials (No. <NUM>-<NUM>, <NUM>, and <NUM>) without a coating layer, the electrode active materials (No. <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>) with a coating layer have the following beneficial effects:.

According to some embodiments of this application, this application provides a battery. <FIG> shows a battery <NUM> according to an embodiment of this application. <FIG> is a schematic diagram of a housing of a battery, and <FIG> is a schematic diagram of the housing and a cover plate of the battery. As shown in <FIG> and <FIG>, in this embodiment, the battery may also be referred to as a battery cell <NUM>. The battery cell <NUM> includes a housing <NUM>, an electrode assembly <NUM>, and an electrolyte, where the electrode assembly <NUM> is accommodated in the housing <NUM> of the battery cell <NUM>, and the electrode assembly <NUM> includes a positive-electrode plate, a negative-electrode plate, and a separator. The separator may be the separator prepared in the embodiments of this application. The electrode assembly <NUM> may be a wound structure or a stacked structure, and may, for example, be the structure actually used in the embodiments of this application. The housing <NUM> includes a shell <NUM> and a cover plate <NUM>. The shell <NUM> includes an accommodating cavity 211a formed by a plurality of walls, and an opening 211b. The cover plate <NUM> is disposed on the opening 211b to seal the accommodating cavity 211a. In addition to the electrode assembly <NUM>, the accommodating cavity 211a further accommodates the electrolyte. The positive-electrode plate and the negative-electrode plate of the electrode plate assembly <NUM> are generally provided with tabs. The tabs generally include a positive-electrode tab and a negative-electrode tab. According to some embodiments of this application, a plurality of positive-electrode tabs are provided and stacked together, and a plurality of negative-electrode tabs are provided and stacked together. The tabs are connected to a positive-electrode terminal 214a and a negative-electrode terminal 214b outside the battery cell <NUM> through connection members <NUM>. In the description of this application, the positive-electrode terminal 214a and the negative-electrode terminal 214b are collectively referred to as an electrode terminal <NUM>. For a prismatic cell, the electrode terminal <NUM> may generally be disposed on the cover plate <NUM>.

According to some embodiments of this application, this application provides an apparatus. The apparatus may include a mobile phone, a portable device, a laptop, an electric scooter, an electric vehicle, a steamship, a spacecraft, an electric toy, an electric tool, or the like. The spacecraft may include an airplane, a rocket, a space shuttle, a spaceship, or the like. The electric toy includes a fixed or mobile electric toy, such as a game console, an electric vehicle toy, an electric ship toy, and an electric airplane toy. The electric tool includes an electric metal cutting tool, an electric grinding tool, an electric assembly tool, and an electric railway-specific tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an electric impact drill, a concrete vibrator, and an electric planer.

Claim 1:
An electrode active material with a coating layer, comprising:
a core, comprising a ternary material, wherein the ternary material comprises one or more of the following: lithium nickel cobalt manganese oxides and lithium nickel cobalt aluminum oxides; and
a coating layer, wherein the coating layer coats at least part of a surface of the core, the coating layer comprises a reaction product of a sulfur-containing compound and a lithium-containing compound, and the reaction product comprises element Li, an element S, and element O, characterized in that the coating layer further comprises one or more of element B, element P, and element F;
under a condition that element B is comprised, a weight content of element B in the electrode active material is <NUM>-<NUM> ppm;
under a condition that element P is comprised, a weight content of element P in the electrode active material is <NUM>-<NUM> ppm;
under a condition that element F is comprised, a weight content of element F in the electrode active material is <NUM>-<NUM> ppm.