JP6931090B2 - Anode composition and method of prelithiumization of anode - Google Patents

Description

The present invention includes a silicon-based active material, a binder selected from polyimic acid and polyimide, and a lithium salt that can be decomposed into lithium oxide and / or lithium peroxide at a temperature of 200 to 400 ° C. The present invention relates to an anode composition for a lithium ion battery. The present invention also relates to a method of making an anode, a method of prelithiumizing the anode, and a lithium ion battery comprising the anode.

Lithium-ion batteries are now widely used in energy storage systems and electric vehicles.

Silicon is a promising active material for the anode of lithium-ion batteries due to its large theoretical capacity and moderate operating voltage. However, during the lithiumization / delithiumization process, silicon undergoes significant expansion and contraction. Such very large volume changes impair the electrochemical performance of lithium-ion batteries. Furthermore, the silicon on the surface of the anode undesirably reacts with the electrolyte to form a solid electrolyte interface (SEI), causing rapid capacity fading in the lithium ion battery.

It has been proposed to add lithium oxide or lithium peroxide into the anode to prelithiumize the anode and compensate for capacitance decay. The prelithiumized anode will continue to be assembled into a lithium-ion battery. However, due to the high activity of lithium oxide and lithium peroxide, the battery manufacturing procedure according to the prelithiumization step requires a well-controlled operating environment of humidity, which increases the manufacturing cost of the lithium ion battery. In addition, lithium oxide and lithium peroxide powders are corrosive or irritating to human skin and mucous membranes and therefore require complete protection in industrial production.

There is a continuing demand for more attractive and reliable lithium-ion batteries.

After intensive research, the inventors
Silicon-based active material and
With a binder selected from polyimic acid and polyimide,
A lithium salt that can be decomposed into lithium oxide and / or lithium peroxide at a temperature of 200 to 400 ° C., preferably 300 to 370 ° C., more preferably 340 to 360 ° C.
We have developed a new anode composition for lithium-ion batteries, including.

In some examples, the anode composition further comprises a carbon material.

To form a slurry by mixing all the components of the anode composition according to the present disclosure with a solvent, and
Applying the slurry to the anode current collector,
Also provided is a method of making an anode, including.

A method of prelithiumizing the anode produced by the method of the present disclosure is also provided, in which the anode is heated to a temperature of 200-400 ° C, preferably 300-370 ° C, more preferably 340-360 ° C. Includes the decomposition of lithium salts into lithium oxide and / or lithium peroxide.

Lithium-ion batteries are also provided that include an anode made according to the methods of the present disclosure or a prelithiumized anode according to the methods of the present disclosure.

For the first time, the inventors combined polyimide and / or polyimic acid with certain lithium salts. At the time of in situ heating, the lithium salt may decompose into lithium oxide and / or lithium peroxide. The lithium oxide and / or lithium peroxide thus obtained can supply additional lithium to the anode to compensate for capacitance attenuation and thus significantly improve battery performance (eg, initial Coulomb efficiency).

Compared to known methods that directly use lithium oxide or lithium peroxide, the present disclosure requires special operating conditions as environmentally friendly, conductive and as a precursor of lithium oxide and / or lithium peroxide. Do not use lithium salts.

In addition, polyimide has good mechanical strength and is stable at the decomposition temperature of lithium salts. Therefore, polyimide is superior to conventional binders used in batteries, such as polyvinylidene fluoride (PVDF) and sodium carboxymethyl cellulose (CMC).

Additional features and advantages of the present disclosure will become apparent when the following detailed description is associated with, by way of example, the accompanying drawings that together represent the technical features.

The cycle performance is compared between the cells according to the examples of the present disclosure and the cells of the comparative examples. The discharge / charge profiles are compared between the cells according to the examples of the present disclosure and the cells of the comparative examples.

Although some exemplary examples are referred to herein, specific terms are used herein to illustrate the examples. However, it will be understood that this is not intended to limit the scope of this disclosure.

Throughout this disclosure, all scientific and technical terms shall have the same meaning as known to those of skill in the art, unless otherwise stated. In case of conflict, the definitions provided in this disclosure should be used.

It should be understood that the detailed description of all materials, processes, examples, and drawings is provided for illustrative purposes only and will not be construed as a limitation of the present disclosure unless expressly specified otherwise. be.

As used herein, the terms "cell" and "battery" may be used interchangeably. The term "lithium ion cell (or battery)" may also be abbreviated as "cell" or "battery".

As used herein, the term "contains" means that other components or other steps that do not affect the end effect can be included. The term includes the terms "consisting of" and "consisting essentially of". The products and processes according to the present disclosure are the essential technical features and / or limitations of the present disclosure described herein, as well as any additional and / or optional components, components, described herein. It can include, consist of, or essentially consist of steps, or limitations.

In the context of the description of the subject matter of this application (particularly in the context of subsequent claims), the terms "one (a)", "one (an)", and "the" and The use of similar referents should be construed to include both singular and plural, unless otherwise stated or clearly inconsistent with the context.

Unless otherwise specified, all numeric ranges in this context are intended to include both endpoints and any numbers and subranges contained within that numeric range.

Unless otherwise specified, all materials and reagents used in this disclosure are commercially available.

Examples of the present disclosure will be described in detail below.

Anode The components of the "anode composition" may be mixed with a solvent to form an anode slurry. Subsequently, the anode slurry may be applied onto the anode current collector and dried to form the anode.

In some examples,
Silicon-based active material and
With a binder selected from polyimic acid and polyimide,
A lithium salt that can be decomposed into lithium oxide and / or lithium peroxide at a temperature of 200 to 400 ° C., preferably 300 to 370 ° C., more preferably 340 to 360 ° C.
An anode composition for a lithium ion battery comprising the above is provided.

In some examples, the anode composition may further comprise a carbon material.

In some embodiments, the anode composition is relative to the total weight of the anode composition.
With 5-60% by weight, preferably 5-40% by weight of silicon-based active material,
With 3-15% by weight, preferably 3-10% by weight of binder selected from polyimic acid and polyimide,
A lithium salt of 2 to 30% by weight, preferably 2 to 20% by weight, which can be decomposed into lithium oxide and / or lithium peroxide at a temperature of 200 to 400 ° C.
From 0 to 90% by weight, preferably 30 to 85% by weight, more preferably 40 to 85% by weight of carbon material.
including.

Each component of the anode composition of the present disclosure will be described in detail below.

Silicon-based active material The anode composition according to the present disclosure may contain a silicon-based active material. Compared to carbon-based active materials, silicon-based active materials have a larger theoretical capacity and a more moderate operating voltage.

As used herein, the term "active material" means a material in which lithium ions can be inserted and released during repeated charge / discharge cycles.

The "silicon-based active material" may be an active material containing a silicon element. The silicon-based active material is not particularly limited, and a material known to be used in a lithium ion battery may be used. Examples of suitable silicon-based active materials include, but are not limited to, silicon, silicon alloys, silicon oxides, silicon / carbon composites, silicon oxide / carbon composites, and any combinations thereof. .. In some embodiments, the silicon alloy may comprise silicon and one or more metals selected from the group consisting of Ti, Sn, Al, Sb, Bi, As, Ge and Pb. Commercially available silicon alloys may include, but are not limited to, Si—Fe—Ti alloy powders available from 3M. In some embodiments, the silicon oxide may be a mixture of two or more silicon oxides. For example, the silicon oxide may _{be represented as SiO x} , and the average value of x may be about 0.5 to about 2.

In some examples, the content of the silicon-based active material is 5 to 60% by weight, preferably 5 to 40% by weight, based on the total weight of the anode composition. The total weight of the anode composition means the dry weight excluding the weight of the solvent.

Binder The anode composition according to the present disclosure may contain a binder selected from polyimic acids and polyimides. The binder holds the components of the anode composition together, attaches the anode composition to the anode current collector, and stabilizes and completes the anode when volume changes occur during repeated charge / discharge cycles. It can help maintain properties and thus improve the electrochemical properties of the final cell, including cycle and rate performance.

In addition, polyimic acids and polyimides have higher thermal resistance and are more stable at the decomposition temperature of the lithium salt than conventional binders (eg PVDF and CMC) that cannot withstand the high decomposition temperature of the lithium salt. ing. In some embodiments, the resulting polyimide is stable at high temperatures, even if the polyimic acid can be dehydrated by heating. In addition, polyimic acids and polyimides have good mechanical strength, which helps prevent volume changes during repeated charge / discharge cycles and is therefore beneficial to the electrochemical properties of the final cell. be.

The polyimide and the polyimic acid are not particularly limited, and generally known ones may be used.

The polyimide may include an aromatic polyimide, an aliphatic polyimide, and an alicyclic polyimide. The polyimide repeating unit may include -C (O) -NC (O)-and one or more aromatic, aliphatic and / or alicyclic moieties.

式中、Ｒ^１及びＲ^２は、それぞれ独立して、Ｃ１〜Ｃ１２アルキル基、Ｃ１〜Ｃ１２アルキレン基、又はＣ１〜Ｃ１２アルキニル基、好ましくは、Ｃ１〜Ｃ６アルキル基であってもよく、ｍは２〜５０、好ましくは２〜３０の整数であってもよい。 In some examples, the polyimide may be represented by Chemical Formula I.

In the formula, R ¹ and R ² may be independently C1-C12 alkyl groups, C1-C12 alkylene groups, or C1-C12 alkynyl groups, preferably C1-C6 alkyl groups, where m is It may be an integer of 2 to 50, preferably 2 to 30.

式中、ＡｒはＣ６〜Ｃ３０芳香族基を表し、Ｒ^３はＣ１〜Ｃ１２アルキル基、Ｃ１〜Ｃ１２アルケニル基、又はＣ１〜Ｃ１２アルキニル基、好ましくは、Ｃ１〜Ｃ６アルキル基であってもよく、ｎは２〜５０、好ましくは２〜３０の整数であってもよい。 In some examples, the polyimide can be represented by Chemical Formula II.

In the formula, Ar represents a C6-C30 aromatic group, and R ³ may be a C1-C12 alkyl group, a C1-C12 alkenyl group, or a C1-C12 alkynyl group, preferably a C1-C6 alkyl group. n may be an integer of 2 to 50, preferably 2 to 30.

式中、Ｒ^３及びｎはそれぞれ、化学式ＩＩについて上述したものと同じ定義を有し、Ｒ^４は独立してＣ１〜Ｃ１２アルキル基、Ｃ１〜Ｃ１２アルケニル基、又はＣ１〜Ｃ１２アルキニル基、好ましくはＣ１〜Ｃ６アルキル基であってもよい。 In some examples, the polyimide can be represented by Chemical Formula III.

In the formula, R ³ and n have the same definitions as those described above for Chemical Formula II, respectively, and R ⁴ is independently a C1-C12 alkyl group, a C1-C12 alkenyl group, or a C1-C12 alkynyl group, preferably a C1-C12 alkynyl group. It may be a C1-C6 alkyl group.

The polyimic acid may include an aromatic polyimic acid, an aliphatic polyimic acid, and an alicyclic polyimic acid. The repeating unit of the polyimic acid may include a carboxy group-C (O) OH, a polyamide group-C (O) -NH-, and one or more aromatic, aliphatic and / or alicyclic moieties. ..

式中、Ａｒ、Ｒ^３、及びｎはそれぞれ、化学式ＩＩについて上述したものと同じ定義を有する。 In some examples, the polyimic acid can be represented by formula IV.

In the formula, Ar, R ³ , and n each have the same definition as described above for Chemical Formula II.

式中、Ｒ^３、Ｒ^４、及びｎはそれぞれ、化学式ＩＩＩについて上記で説明したものと同じ定義を有する。 In some examples, the polyimic acid can be represented by formula V.

In the formula, R ³ , R ⁴ , and n each have the same definitions as those described above for Chemical Formula III.

To facilitate the application of the anodic slurry to the anodic current collector, the polyimic acid and polyimide should be soluble in the solvent used to form the anodic slurry (eg, N-methyl-2-pyrrolidone). preferable.

In some examples, the content of the binder is 3 to 15% by weight, preferably 3 to 10% by weight, based on the total weight of the anode composition.

Lithium Salt The anode composition according to the present disclosure is a lithium salt that can be decomposed into lithium oxide and / or lithium peroxide at a temperature of 200 to 400 ° C., preferably 300 to 370 ° C., more preferably 340 to 360 ° C. It may be included.

At the time of in situ heating, the lithium salt may decompose into lithium oxide and / or lithium peroxide. The lithium oxide and / or lithium peroxide thus obtained can provide an additional lithium source to compensate for capacitance attenuation and thus significantly improve battery performance (eg, initial Coulomb efficiency).

Compared to known methods that directly use lithium oxide or lithium peroxide, the present disclosure uses lithium salts as precursors of lithium oxide that are environmentally friendly, conductive and do not require special operating conditions. ing.

In some examples, the lithium salt is selected from the group consisting of lithium acetate, lithium oxalate, lithium citrate, and lithium bicarbonate.

The weight ratio of lithium salt to silicon-based active material depends on the particular type of lithium salt and silicon-based active material used. Preferably, the weight ratio of lithium in the lithium salt to silicon in the silicon-based active material is 5: 100 to 25: 100, preferably 7: 100 to 20: 100. By controlling the ratio of lithium to silicon within these ranges, the battery can be prelithiumized to the desired high level, while avoiding excessive introduction of lithium and reduction of the mass density of the battery. Can be done.

In some examples, the content of the lithium salt is 2-30% by weight, preferably 2-20% by weight, based on the total weight of the anode composition.

Solvent As described above, the anode composition according to the present disclosure may be mixed with a solvent to form an anode slurry. Heating the anode during the subsequent prelithiumization step causes the solvent to evaporate. Therefore, the prelithiumized anode contains only a small amount of solvent or does not contain solvent.

The solvent is not particularly limited, and those known to be used in lithium ion batteries may be used. Examples of suitable solvents include N-methyl-2-pyrrolidone (NMP).

Carbon Material The anode composition may further comprise a carbon material. The "carbon material" may be a material containing a carbon element. The carbon material may function as an active material different from the silicon-based active material, or can enhance the electrical conductivity and / or dispersibility of the anode composition. The carbon material is not particularly limited, and those known to be used in lithium ion batteries may be used. In some embodiments, the carbon material may include carbon black, acetylene black, ketjen black, graphite, graphene, carbon nanotubes, carbon fibers, vapor grown carbon fibers, and combinations thereof. Not limited. In some examples, the carbon black may be Super P (eg, Super P commercially available from Timcal, particle size: about 20 nm or about 40 nm). In some examples, the graphite may be graphite powder (eg, particle size: 2-30 μm) and / or graphite flakes (eg, KS6L commercially available from Timcal, particle size: about 6 μm). The carbon materials may be used individually or in any combination.

In some examples, graphite powder, Super P, and graphite flakes may be used in combination of two or three of these. The graphite powder functions as a carbon-based active material at the anode, thereby buffering the volume change caused by the silicon-based active material. Super P has a relatively small particle size and good electrical conductivity, and can improve the electrical conductivity and dispersibility of the anode. Graphite flakes have a relatively large particle size and good electrical conductivity, which can improve two-dimensional electrical conductivity, two-dimensional dispersibility, and cycle performance.

In addition to the components described above, the anode may optionally contain additives commonly used in electrodes as long as the battery performance is not significantly impaired.

There are no particular restrictions on the type, shape, size, and / or content of each component of the anode composition.

In some examples, the content of the carbon material is 0-90% by weight, preferably 30-85% by weight, more preferably 40-85% by weight, based on the total weight of the anode composition.

Anode Fabrication Methods In some embodiments, anode fabrication methods are provided, the method of which is:
To form a slurry by mixing all the components of the anode composition according to the present disclosure with a solvent, and
Includes applying the slurry to an anode current collector.

In some examples, the solvent may include N-methyl-2-pyrrolidone (NMP).

There are no specific restrictions on the anode current collector. In some embodiments, nickel foil, nickel mesh, copper foil, or copper mesh may be used as the anode current collector.

In some embodiments, the method further comprises a calendaring step. During the decomposition of the lithium salt, gas is generated to form porosity. The calendering may satisfactorily control the porosity of the anode, may evenly distribute lithium oxide and / or lithium peroxide on the anode, and may improve battery performance.

Methods of Prelithiumizing Anodes In some embodiments, methods of prelithiumizing an anode produced by the methods of the present disclosure are provided, the method being 200-400 ° C, preferably 300-370 ° C, more. Preferably, it comprises heating the anode to a temperature of 340-360 ° C. to decompose the lithium salt into lithium oxide and / or lithium peroxide. When the temperature is within these ranges, the polyimide and / or polyimic acid show good cross-linking strength and the electrode current collector is not destroyed.

Lithium Ion Batteries In some embodiments, lithium ion batteries are provided, which include an anode made or prelithiumized according to the methods of the present disclosure. In addition, lithium-ion batteries also include cathodes and electrolytes.

Lithium-ion batteries according to the present disclosure may be used in energy storage systems and electric vehicles.

Cathode The "cathode composition" may be mixed to form a cathode slurry. Subsequently, the cathode slurry may be applied onto the cathode current collector and dried to form the cathode.

According to some examples of the present disclosure, the cathode may contain a lithium-based active material. In some embodiments, the cathode active material may be a material that reversibly disengages and inserts lithium ions during the charge / discharge cycle. In the discharge cycle, the lithium ions derived from the lithium-based active material can return from the anode to the cathode to form the lithium-based active material again.

The lithium-based cathode active material is not particularly limited, and a cathode active material generally used in a lithium ion cell may be used. In some embodiments, the cathode active material is a lithium metal oxide, a lithium metal phosphate, a lithium metal silicate, and any combination thereof, preferably a lithium transition metal composite oxide, a lithium transition metal phosphorus. It may be selected from the group consisting of acid salts, lithium metal silicates, and any combination thereof. In some examples, the cathode active material may be selected from the group consisting of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and any combination thereof. In some examples, the lithium transition metal composite oxide is lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (NCM). ), Lithium Nickol Cobalt Aluminum Oxide (NCA), Lithium Nickol Cobalt Manganese Oxide / Li ₂ MnO ₃ Complex (also referred to as "Lithium Rich NCM"), or any combination thereof. .. The transition metal may include any transition metal of groups 3 to 12 of the periodic table, such as titanium, zinc, copper, nickel and molybdenum.

In some examples, the cathode composition may further comprise a carbon material, a binder, and a solvent in addition to the lithium-based cathode active material.

The binder is not particularly limited, and those known to be used in lithium ion batteries may be used. In some examples, the binder may be polyvinylidene fluoride (PVDF), polyacrylic acid (PAA) and its derivatives (eg LiPAA), sodium carboxymethyl cellulose (CMC), and combinations thereof. ..

The above description of carbon materials and solvents in the anode can also be applied here. The carbon material and solvent in the cathode may be the same as or different from those contained in the anode, respectively.

In addition, other additives commonly known to be used in lithium-ion batteries may optionally be used at the cathode as long as they do not adversely impair the desired performance of the battery.

There are no particular restrictions on the type, shape, size, and / or content of each component of the cathode composition.

There are no specific restrictions on the cathode current collector. In some embodiments, aluminum foil may be used as the cathode current collector.

Electrolyte The lithium ion battery according to the present disclosure may contain an electrolyte. According to some examples of the present disclosure, the electrolyte may include lithium salts and non-aqueous solvents. The lithium salt and the non-aqueous solvent are not particularly limited, and the lithium salt and the non-aqueous solvent generally known in the cell may be used. In some embodiments, the lithium salt in the electrolyte may differ from the lithium-based active material in the cathode and the lithium salt in the anode. According to some examples of the present disclosure, the lithium salts are lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), _{lithium hydride (LiAsO 4} ), LiSbO ₄ , lithium perchlorate. (LiClO ₄ ), LiAlO ₄ , LiGaO ₄ , lithium bis (oxalate) borate (LiBOB), and any combination thereof may be included, with LiPF ₆ being particularly preferred, but not limited to these.

According to some examples of the present disclosure, the non-aqueous solvent in the electrolyte may include carbonates (ie, non-fluorinated carbonates) and fluorinated carbonates. According to some examples of the present disclosure, carbonates are cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC); dimethyl carbonate (DMC), diethyl carbonate (DEC), Linear or branched carbonates such as dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC); and any combination of carbonates described above. It may include, but is not limited to. According to some examples of the present disclosure, the fluorinated carbonate may be a fluorinated derivative of the carbonate described above, such as fluoroethylene carbonate (FEC) and difluoroethylene carbonate, difluorinated dimethyl carbonate (DFDMC). ..

Materials NCM-111: Lithium Nickel Cobalt Manganese Oxide, Cathode Active Material, D50: 12 μm, available from BASF.
Super P: Cathode and anode carbon material, 40 nm, available from Timcal.
PVDF: Polyvinylidene fluoride, cathode binder, available from Sovey.
Si-Fe-Ti alloy powder: Anode active material, silicon content: 30% by weight, diameter: 50nm, available from 3M.
Graphite powder: Anode active material, diameter: 20 μm, available from Hitachi.
KS6L: Graphite flakes, carbon material for anodes, about 6 μm, available from Timcal.
U-Varnish A: Anode binder, mixture of 20% by weight polyamic acid and 80% by weight N-methyl-2-pyrrolidinone, available from UBE.
Lithium acetate: Lithium salt, source of prelithiumization of anode, available from Guoyao.
NMP: N-methyl-2-pyrrolidone, solvent, available from Guoyao.
Celgard 2325: PP / PE / PP membrane, separator, available from Celgard.

Example 1 (Ex.1): Cell fabrication Cathode fabrication At room temperature, 96.5 g of NCM-111, 3 g of Super P, and 2.5 g of PVDF in a 500 mL round bottom flask equipped with a stirrer. Added to 47 g of NMP. After stirring for 3 hours, the resulting uniformly dispersed slurry was coated on aluminum foil and then dried at 80 ° C. for 6 hours. The coated aluminum foil was cut into several Φ12 mm cathodes.

Anode Preparation At room temperature, 40 g Si-Fe-Ti alloy powder, 40 g graphite powder, 10 g lithium acetate, 10 g U-Varnish A (dry weight, in the form of a 20 wt% solution in NMP), 2 g Super P and 8 g of KS6L were added to 70 g of NMP in a 500 mL round bottom flask equipped with a stirrer. After stirring for 3 hours, the obtained uniformly dispersed slurry was coated on a copper foil and then dried at 60 ° C. for 30 minutes. The coated copper foil was then fired in a nitrogen gas-purged tube furnace (RS80 / 750/11, Navertherm) at a heating rate of 20 ° C./min until the temperature reached 350 ° C. Subsequently, the coated copper foil was removed from the tube furnace and cooled to room temperature (about 25 ° C.). The coated copper foil was cut into several Φ12 mm anodes.

Cell Preparation A coin cell (CR2016) was assembled using the cathode and anode obtained above in an argon-filled glove box (MB-10 compact, MBran). _{1M LiPF 6} in FEC / EC / EMC (volume ratio 30:35:35) was used as the electrolyte. Celgard 2325 was used as the separator.

Comparative Example 1 (Com.Ex.1)
A coin cell was prepared by the same method as in Example 1 above except that lithium acetate was not used.

[Electrochemical measurement]
The battery performance of each cell obtained in Example 1 and Comparative Example 1 was measured at 25 ° C. with an Arbin battery test system (model: Arbin BT-G; supplier: Arbin).

Each cell was charged to 4.2 V ^{(relative to Li / Li +} ) with a current of 0.1 C in the first charge cycle. The cell was then discharged to 2.5 V with a current of 0.1 C in the first discharge cycle. The charge / discharge cycle described above was repeated in the second and third cycles. Subsequently, in the 4th to 21st charge cycles, each cell was charged to 4.2 V ^{(relative to Li / Li +) at various rates.} Specifically, the charging rate is 0.1C for the 4th to 6th charging cycles, 1 / 3C for the 7th to 9th charging cycles, 0.5C for the 10th to 12th charging cycles, and 13th. It was 1C in the 15th charge cycle, 2C in the 16th to 18th charge cycles, and 3C in the 19th to 21st charge cycles. In the 4th to 21st discharge cycles, the cell was discharged to 2.5 V with a current of 0.1 C. Finally, each cell was discharged / charged in the voltage range of 2.5 to 4.5 V ^{(relative to Li / Li +} ) at a rate of 1 C in subsequent cycles. The mass load of NCM at each cathode of the cell was about 10 mg / cm ² . Specific volume was calculated based on the weight of NCM.

FIG. 1 compares the cycle performance of the cell of Example 1 and the cell of Comparative Example 1. With reference to FIG. 1, it can be seen that Example 1 exhibited better cycle stability as compared to Comparative Example 1 without the prelithiumized source.

FIG. 2 compares the discharge / charge profiles of the cell of Example 1 and the cell of Comparative Example 1. With reference to FIG. 2, it can be seen that Example 1 exhibited higher initial Coulomb efficiency in the first charge / discharge cycle as compared to Comparative Example 1 without the prelithiumized source.

Claims (10)

Anode composition for lithium-ion batteries
Based on the total weight of the anode composition
With 5 to 60% by weight of silicon-based active material,
With 3-15% by weight of binder selected from polyimic acid and polyimide,
With 2 to 30% by weight lithium salt, which can be decomposed into lithium oxide and / or lithium peroxide at a temperature of 200-400 ° C.
From 0 to 90% by weight of carbon material,
Anode composition containing. The anode composition according to claim 1, wherein the binder is soluble in N-methyl-2-pyrrolidone. The anode composition according to claim 1 or 2, wherein the lithium salt is selected from the group consisting of lithium acetate, lithium citrate, lithium citrate, and lithium bicarbonate. The invention according to any one of claims 1 to 3, wherein the silicon-based active material is selected from the group consisting of silicon, a silicon alloy, a silicon oxide, a silicon / carbon composite material, and a silicon oxide / carbon composite material. Anode composition. The anode composition according to any one of claims 1 to 4, wherein the anode composition further comprises a carbon material. The anode composition according to claim 5, wherein the carbon material is selected from the group consisting of carbon black, acetylene black, ketjen black, graphite, graphene, carbon nanotubes, carbon fibers, and vapor-grown carbon fibers. Based on the total weight of the anode composition
With 5-40% by weight of silicon-based active material,
With 3-10 wt% binder selected from polyimic acid and polyimide,
With 2 to 20% by weight lithium salt, which can be decomposed into lithium oxide and / or lithium peroxide at a temperature of 200-400 ° C.
With 30-85% by weight of carbon material,
The anode composition according to any one of claims 1 to 6, which comprises. The anode composition according to claim 7 , which comprises 40 to 85% by weight of a carbon material based on the total weight of the anode composition. A method of making an anode,
To form a slurry by mixing all the components of the anode composition according to any one of claims 1 to 8 with a solvent.
Applying the slurry to the anode current collector,
Including methods. A method for prelithiumizing an anode produced according to the method according to claim 9 , wherein the anode is heated to a temperature of 200 to 400 ° C. to decompose the lithium salt into lithium oxide and / or lithium peroxide. The method, including that.

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