Silicon Anode-Based Lithium-Ion Battery

Abstract

A silicon polymer composite anode suitable for use in an electrochemical energy storage device; a method for manufacturing the anode, the method comprising the steps of mixing silicon particles and at least one polymer to form a mixture, coating the mixture on a current collector to form a coated copper current collector, and subjecting the coated copper current collector to a heat treatment to form the anode; and a dual electrolyte for improving the conductivity, specific capacity, rate characteristics, and stability of the anode are disclosed.

Description

Technical Field

[0001] This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 63 / 224,217, filed on July 21, 2021, which is hereby incorporated by reference in its entirety.

[0002] Field The present disclosure relates to an electrochemical energy storage device, a silicon-polymer composite anode suitable for use in an electrochemical energy storage device including an anode and an electrolyte, a method for manufacturing the anode, and dual salt electrolytes for improving the conductivity, specific capacity, rate performance, and stability of the anode.

Background Art

[0003] Background Lithium-ion (Li-ion) batteries are widely used in household appliances, electric vehicles (EVs), and energy storage systems (ESSs) and smart grids. The energy density of a battery depends on the materials of the anode and cathode used, and by optimizing processing and manufacturing, an improvement in energy density of 4 - 5% per year has been made possible, but these increases are not significant. To achieve the energy density targets of next-generation energy technologies, progress in electrode materials is required, and there is an urgent need to incorporate high-energy-density active materials. Many studies have focused on the development of high-energy cathodes, but research on anode materials is limited.

[0004] Recently, silicon (Si) has emerged as one of the most attractive high-energy anode materials for Li-ion batteries. The main reason for this interest is that silicon has a low operating voltage and a high theoretical specific capacity of 3579 mAh / g, which is nearly 10 times that of conventional graphite. Despite this significant advantage, silicon anodes face several challenges related to severe volume expansion and accompanying particle fracture. Graphite electrodes expand by 10 - 15% during lithium intercalation, while Si electrodes expand by approximately 300%, which causes structural degradation and destabilization of the solid electrolyte interface (SEI) layer. This leads to material pulverization and electrode delamination, resulting in capacity loss during cycling. To mechanically suppress the expansion, contraction, and fragmentation of silicon particles, it is important to coat the active material silicon with a conductive polymer material as a binder. Similarly, an electrochemically robust SEI layer prevents side reactions that cause capacity degradation.

[0005] Silicon particle decomposition can be mitigated by using active material particles less than 150 nm or by using other nanostructures, but cells using such anode designs are limited by the low loading of the nanosilicon material (less than 15 mass%). Furthermore, in these anode designs, the SEI layer is constantly disrupted during the expansion and contraction of silicon, resulting in insufficiently high Coulombic efficiency. SUMMARY OF THE INVENTION MEANS FOR SOLVING THE PROBLEMS

[0006] SUMMARY According to one aspect of the present disclosure, there is provided an anode for an electrochemical energy storage device including silicon particles and a polymer; a method for manufacturing a silicon-polymer composite anode; and an electrochemical energy storage device using a dual salt electrolyte.

[0007] According to another aspect of the present disclosure, an anode for an electrochemical energy storage device is provided that includes a plurality of silicon active materials having a particle size of 1 nm to 100 μm. Other active materials may include, but are not limited to, silicon composite materials, graphite, hard carbon, tin, and germanium particles.

[0008] According to another aspect of the present disclosure, an anode for an electrochemical energy storage device is provided that includes a polymer material in which at least one polymer material is PAN.

[0009] According to another aspect of the present disclosure, PAN can be cyclized using heat treatment at a temperature of 200 to 600 °C and can be converted into a ladder compound by cross-linking the polymer chains, and the nitrile bond (C≡N) changes to a double bond (C=N) by cyclization. The polymer binder forms a resilient yet robust film, which enables controlled fragmentation / crushing of the silicon particles within the binder matrix. The resulting anode material can overcome the swelling and conductivity issues of silicon-based anodes, for example, by providing a binder that can prevent the swelling of silicon particles and a conductive additive that provides a migration path for Li ions. The polymer is about 10 to 40 wt.% of the anode composite material.

[0010] This specification describes various embodiments of silicon-polymer composite anodes and methods for making them. The method for making the composite anode includes the steps of mixing silicon, a polymer, and a solvent together; coating the mixture onto a copper current collector to form a coated copper current collector; and subjecting the coated copper current collector to a temperature treatment. According to one aspect of the present disclosure, the temperature treatment can include heating the coated copper current collector in an inert atmosphere in a temperature range of 200 to 600 °C.

[0011] According to another aspect of the present disclosure, an electrochemical energy storage device includes an anode, a cathode, and an electrolyte.

[0012] According to another aspect of the present disclosure, Li + ion salts are provided with a dual salt electrolyte that is lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI).

[0013] According to another aspect of the present disclosure, a dual salt electrolyte is provided in which the electrolyte includes an aprotic organic solvent system and at least one additive.

[0014] According to another aspect of the present disclosure, a dual salt electrolyte is provided, wherein the electrolyte includes an aprotic organic solvent system and at least one additive; the aprotic organic solvent includes an aprotic organic solvent of an open-chain or cyclic carbonate, and at least one solvent is fluoroethylene carbonate (FEC), carboxylic acid ester, nitrite, ether, sulfone, sulfoxide, ketone, lactone, dioxolane, glyme, crown ether, siloxane, phosphate ester, phosphite, monophosphazene or polyphosphazene, or a mixture thereof.

[0015] According to another aspect of the present disclosure, a dual salt electrolyte is provided, wherein the electrolyte includes an aprotic organic solvent system and at least one additive; the additive contains a compound containing at least one unsaturated carbon-carbon bond, carboxylic anhydride, sulfur-containing compound, phosphorus-containing compound, boron-containing compound, silicon-containing compound, nitrogen-containing compound, or a mixture thereof.

[0016] These and other aspects of the present disclosure will become apparent upon review of the following detailed description and the appended claims.

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0023] Detailed Description The embodiments form a part of this specification and are more fully described below with reference to the accompanying drawings, which show specific exemplary embodiments by way of illustration. These embodiments are disclosed in sufficient detail so that those skilled in the art can practice the present invention. However, the embodiments can be implemented in many different forms and should not be construed as limited to the embodiments described herein. Therefore, the following detailed description should not be construed in a limiting sense.

[0024] This specification discloses a silicon-polymer composite anode for a silicon anode-based Li-ion battery with a dual salt electrolyte. A polymer, mainly polyacrylonitrile (PAN), forms a mechanically stable yet elastic film around the silicon active material particles, enabling self-contained fragmentation. Further, a dual salt electrolyte containing a fluorinated solvent and an ionic liquid additive forms a robust SEI to prevent anode degradation due to contact with the electrolyte and resulting side reactions.

[0025] The disclosed technology generally relates to anodes of electrochemical energy storage devices. In particular, this disclosure is directed to a silicon-polymer composite anode; a dual salt electrolyte, and a Li-ion battery containing the anode and the electrolyte.

[0026] This disclosure describes a Li-ion battery anode that can overcome the issues of silicon anode expansion and conductivity. The polymer component of the composite anode, more specifically PAN, functions as a binder for a silicon anode-based Li-ion battery. PAN is used as a polymer binder that forms an elastic yet robust film, enabling controlled fragmentation / milling of silicon particles within the binder matrix. Through heat treatment, PAN is cyclized and the nitrile bond (C≡N) is converted to a double bond (C=N) by cross-linking of PAN molecules. This process produces a ladder polymer chain of elastic yet mechanically robust PAN fibers, thus enabling controlled fragmentation of silicon particles. Further, the PAN matrix also provides a migration path for Li-ions, thereby enhancing the conductivity of the composite anode.

[0027] In one embodiment, an anode for an electrochemical energy storage device comprising silicon particles, a polymer; and a method for manufacturing a silicon-polymer composite anode are provided, wherein the silicon particles of the silicon-polymer composite anode are suitably and sufficiently coated with a binder material.

[0028] Any suitable Si composite material can be used for the silicon particles included in the anode materials described herein. In some embodiments, the silicon particles Si composite particles include Si-carbon composite materials such as carbon-coated Si particles. In some embodiments, silicon oxide (SiO x ) is used. The Si composite may be an alloy of Si and an inert metal or nonmetal. Other examples of Si composite materials suitable for use in the embodiments described herein are graphene-silicon composites, graphene oxide-silicon-carbon nanotubes, silicon-polypyrrole, and composites of nanosize and micron-size silicon particles. As described above, any combination of Si composite materials can be used for the anode material, or only a single Si composite material can be used.

[0029] In one embodiment, a method for producing silicon particles; an anode for an electrochemical energy storage device comprising a polymer; and a silicon-polymer composite anode is provided, where the form of silicon includes, but is not limited to, nanorods, nanospheres, nanowires, and other types of nanosize and micron-size silicon particles. Carbonaceous materials such as graphite, hard carbon, tin, and germanium particles are additional non-exhaustive and exemplary anode active materials that can be used in addition to the silicon particles. Other conductive additives such as carbon nanotubes and carbon black can be for improving the conductivity of the coating; acids such as citric acid, oxalic acid, and 1,2,3,4-butanetetracarboxylic acid can be used to improve adhesion to the copper current collector.

[0030] In one embodiment, there is provided an anode for an electrochemical energy storage device comprising silicon particles; a polymer; and a method for manufacturing a silicon-polymer composite anode, wherein the silicon, the polymer, and other anode active materials are dispersed using a suitable solvent in any suitable amount. In some embodiments, the solvent is N,N-dimethylformamide. Other solvents include, but are not limited to, N-methyl-2-pyrrolidone (NMP), dimethyl sulfone (DMSO2), dimethyl sulfoxide (DMSO), N-N-dimethylacetamide (DMAc), ethylene carbonate (EC), and propylene carbonate (PC).

[0031] In one embodiment, there is provided an anode for an electrochemical energy storage device comprising silicon particles; a polymer; and a method for manufacturing a silicon-polymer composite anode, wherein the silicon, the polymer, and other materials are mixed together to form a mixture, subsequently a solvent is added to the mixture, the mixture is coated onto a copper current collector, the solvent is removed from the coating, and the coated current collector is subjected to heat treatment.

[0032] In another embodiment, there is provided an anode for an electrochemical energy storage device, which is cyclized by heating in an inert atmosphere in the range of about 200 to 600 °C, for example 240 to 450 °C, by stabilizing PAN to form a ladder polymer compound. This is confirmed using Fourier transform infrared (FT-IR) spectroscopy to analyze the conversion from C≡N to C=N. Upon heat treatment, PAN forms an elastic yet robust film, which enables controlled fragmentation / crushing of the silicon particles within the binder matrix.

[0033] In certain embodiments, provided are anodes for electrochemical energy storage devices comprising silicon particles; a polymer; and a method for manufacturing a silicon-polymer composite anode, wherein the solids in the slurry contain 10-80 wt.% silicon, 10-60 wt.% carbonaceous material, and 10-40 wt.% PAN polymer. An exemplary silicon-polymer anode can contain silicon:carbonaceous material:PAN in a weight ratio of 48:32:18.

[0034] A conductive additive can be added in a low loading of 0.1-5 wt.%, and an acid can be added to the slurry in an amount of 0.01-1 wt.%. Any suitable conductive nanoparticles can be used, including but not limited to VGCF, carbon black, and carbon nanotubes. Adding such conductive additive nanoparticles can enhance the conductivity of the anode material. Acid binders that may be included in the anode slurry used to make the anode material include, for example, oxalic acid, citric acid, maleic acid, tartaric acid, and 1,2,3,4-butanetetracarboxylic acid. The acid binder can be used to improve the dispersibility and adhesion properties. When used in the anode material, the acid binder may be present in the range of about 0.01 to about 2 wt.%.

[0035] In some embodiments, the slurry contains about 30-60 wt.% solids and about 70-40 wt.% solvent. The slurry has a viscosity in the range between 3000-6000 centipoises (cP) when the spindle rotation speed is 20-100 rpm, with a variation of 800-1000 cP for a given slurry.

[0036] In certain aspects of the present disclosure, the electrolyte of the electrochemical energy storage device contains a) a dual salt electrolyte, b) an aprotic organic solvent system, and c) at least one additive.

[0037] In another aspect of the present disclosure, the electrolyte of the electrochemical energy storage device includes: a) a dual salt electrolyte, b) an aprotic organic solvent system, and c) at least one additive; wherein the dual salt contains lithium salts LiPF6 and LiFSI present in the range of 10 to 30 wt.%.

[0038] Various lithium salts can be used in the dual salt electrolyte. For example, Li(AsF6); Li(PF6); Li(CF3CO2); Li(C2F5CO2); Li(CF3SO3); Li[N(CP3SO2)2]; Li[C(CF3SO2)3]; Li[N(SO2C2F5)2]; Li(ClO4); Li(BF4); Li(PO2F2); Li[PF2(C2O4)2]; Li[PF4C2O4]; lithium alkyl fluorophosphate; Li[B(C2O4)2]; Li[BF2C2O4]; Li2[B 12 Z 12-j H j ; Li2[B 10 X 10-j’ H j’ (where Z is independently a halogen each time it appears, j is an integer from 0 to 12, and j' is an integer from 1 to 10); or a mixture of any two or more of these is included.

[0039] In another aspect of the present disclosure, the electrolyte of the electrochemical energy storage device includes: a) a dual salt electrolyte, b) an aprotic organic solvent system, and c) at least one additive; wherein at least one solvent in the aprotic organic solvent system is a fluorinated cyclic carbonate such as fluoroethylene carbonate in the range of 10 to 30 wt.%.

[0040] In another aspect of the present disclosure, the electrolyte further includes an aprotic organic solvent selected from open-chain or cyclic carbonates, carboxylic acid esters, nitrites, ethers, sulfones, sulfoxides, ketones, lactones, dioxolanes, glymes, crown ethers, siloxanes, phosphate esters, phosphites, monophosphazenes or polyphosphazenes, or mixtures thereof, in the range of 40 to 90 wt.%.

[0041] In another aspect of the present disclosure, at least one additive is a compound containing at least one unsaturated carbon-carbon bond, a carboxylic anhydride, a sulfur-containing compound, a phosphorus-containing compound, a boron-containing compound, a silicon-containing compound, a nitrogen-containing compound, or a mixture thereof in the range of 0.1 to 5 wt.%.

[0042] In another aspect of the present disclosure, there is provided an electrochemical energy storage device including the cathode, anode, and electrolyte described herein. In one embodiment, the electrochemical energy storage device is a lithium secondary battery. In some embodiments, the secondary battery is a lithium battery, a lithium ion battery, a lithium sulfur battery, a lithium air battery, a sodium ion battery, or a magnesium battery. In some embodiments, the electrochemical energy storage device is an electrochemical cell such as a capacitor. In some embodiments, the capacitor is an asymmetric capacitor or a supercapacitor. In some embodiments, the electrochemical cell is a primary battery. In some embodiments, the primary battery is a lithium / MnO2 battery or a Li / poly(carbon monofluoride) battery.

[0043] Suitable cathodes include, for example, lithium metal oxides, spinels, olivines, carbon-coated olivines, LiCoO2, LiNiO2, LiMn 0.5 Ni 0.5 O2, LiMn 0.3 Co 0.3 Ni 0.3 O2, LiMn2O4, LiFeO2, LiNi x Co y Met z O2, A n’ B2(XO4)3, vanadium oxide, lithium peroxide, sulfur, polysulfide, lithium monofluoride (LiCF xor mixtures of any two or more thereof, etc., but not limited thereto, where Met is Al, Mg, Ti, B, Ga, Si, Mn or Co; A is Li, Ag, Cu, Na, Mn, Fe, Co, Ni, Cu or Zn; B is Ti, V, Cr, Fe or Zr; X is P, S, Si, W or Mo; and 0 ≦ x ≦ 0.3, 0 ≦ y ≦ 0.5, and 0 ≦ z ≦ 0.5, and 0 ≦ n’ ≦ 0.3. According to some embodiments, the spinel has the formula Li 1+x Mn 2-z Met’’’ y O 4-m X’ n (where Met’’’ is Al, Mg, Ti, B, Ga, Si, Ni or Co; X’ is S or F; and 0 ≦ x ≦ 0.3, 0 ≦ y ≦ 0.5, 0 ≦ z ≦ 0.5, 0 ≦ m ≦ 0.5, and 0 ≦ n ≦ 0.5) is a spinel manganese oxide. In other embodiments, the olivine is LiFePO4, or Li 1+x Fe 1z Met’’ y PO 4-m X’ n of the formula (where Met’’ is Al, Mg, Ti, B, Ga, Si, Ni, Mn or Co; X’ is S or F; and 0 ≦ x ≦ 0.3, 0 0 ≦ y ≦ 0.5, 0 ≦ z ≦ 0.5, 0 ≦ m ≦ 0.5, and 0 ≦ n ≦ 0.5).

[0044] In one embodiment, a secondary battery is provided that includes a porous separator and a positive electrode and a negative electrode separated from each other using the electrolyte described herein.

[0045] Separator suitable for lithium batteries is often a microporous polymer film. Examples of polymers for forming the film include polypropylene, polyethylene, nylon, cellulose, nitrocellulose, polysulfone, polyacrylonitrile, polyvinylidene fluoride, polybutene, or copolymers or blends of any two or more such polymers. In some cases, the separator is an electron beam-treated microporous polyolefin separator. Electron treatment may increase the deformation temperature of the separator, and thus the thermal stability at high temperatures may be improved. Additionally or alternatively, the separator can be a shutdown separator. The shutdown separator has a trigger temperature exceeding about 130 °C, allowing the electrochemical cell to operate at temperatures up to about 130 °C.

Example

[0046] The present disclosure will be further described with reference to the following specific examples. It is understood that these examples are presented by way of illustration and are not intended to limit the present disclosure or the following claims.

[0047] Example A Preparation of Silicon-Polymer Composite Anode

[0048] 48% silicon powder (1 μm) was used as the active material, and the solid was ball-milled at low rpm and mixed with 17.7% PAN. 32% graphite was added to the solid mixture and ball-milled. 2.2% conductive carbon black and 0.1% oxalic acid were dispersed in DMF using a high-shear dispersion method. Next, the solid mixture was added to the dispersion and mixed overnight. The slurry was coated onto a copper current collector using a bench-top doctor blade coater to obtain about 3 mg / cm 2An electrode with a loading amount was obtained. Next, the electrode was dried at 60 °C in a convection oven and then heat-treated at 330 °C in an inert argon gas atmosphere. Figure 1 shows the FTIR spectra of the silicon-polymer composite anode before and after heat treatment at 330 °C in an inert argon gas atmosphere. The peak highlighted with a circle at about 1600 cm -1 corresponds to C=N and is present only in the sample treated at 330 °C, indicating the cyclization of PAN.

[0049] Example B Preparation of silicon-polymer composite anode

[0050] The anode was prepared using the same method as that used in Example A, but citric acid was used instead of oxalic acid.

[0051] Example C Preparation of electrolyte

[0052] The electrolyte formulation was prepared by combining all electrolyte components in a glass vial inside a dry argon-filled glove box and stirring for 24 hours to ensure complete dissolution of the salts. The comparative example (CE) is a commercially available reference electrolyte, and the embodiment example (EE) is an example of a representative electrolyte according to the present disclosure. Different additives were added to the basic formulation for both electrolytes. The electrolyte formulations are summarized in Table A:

Table A

Table B

[0053] Example D Cell fabrication - 65 mAh cell

[0054] The pouch cell was assembled using an NMC811 cathode, as well as the anode listed in Example A, and the electrolyte CEs and EEs listed in Example C. The specific capacity of the NMC811 cathode was about 4.1 mAh / cm 2 , and the loading was about 28 mg / cm 2 . The separator used was polypropylene, and the expected cell capacity was about 65 mAh. The cell was tested in a voltage range of 4.1 - 3.0 V. Figures 2 and 3 are the charge and discharge rate characteristics of a full cell (two cells using electrolyte CEs and EEs respectively) using an NMC811 cathode and a silicon-polymer composite anode according to the present disclosure. As is clear from the data, the dual-salt electrolyte represented by EE exhibits better performance during rapid charging and rapid discharging compared to CE. This may be due to the higher conductivity of EE compared to CE, resulting in faster lithium-ion transport.

[0055] Example E Effect on electrolyte performance

[0056] The electrolyte formulations were prepared as described in Example C. Ionic liquid-based electrolytes (IL1 and IL2) and carbonate-based electrolytes (Carb1 and Carb2) are compared in terms of effectiveness both during formation and cycling. The electrolyte formulations are summarized in Table C.

Table C

[0057] Example F Cell fabrication - 90 mAh cell

[0058] The pouch cell was assembled using an NMC811 cathode, as well as the anode listed in Example A, and the electrolytes IL1, IL2, Carb1, and Carb2 listed in Example E. The specific capacity of the NMC811 cathode was about 4.16 mAh / cm 2 , and the loading was about 21.2 mg / cm 2It was. The separator used was polypropylene, and the expected cell capacity was about 90 mAh or about 180 mAh. The cells were tested in the voltage range of 4.2 - 2.7 V. Figures 4 and 5 show the first and second cycle efficiencies of the full cells using the NMC811 cathode and the silicon-polymer composite anode according to the present disclosure. Figure 6 shows a comparison of the discharge cycle capacities during the C / 3 rate discharge test. As is apparent from the data, the carbonate-based electrolytes represented by Carb1 and Carb2 exhibit better performance in terms of the first cycle efficiency (FCE) compared to CE. This may be due to the fact that the viscosities and resistances of the carbonate-based electrolytes are lower than those of the ionic liquid-based electrolytes, resulting in faster lithium ion transport.

[0059] From the above, it is understood that the specific embodiments of the present invention are described herein for illustrative purposes and that various modifications can be made without departing from the scope of the present invention. Therefore, the present invention is not limited except as by the appended claims.

Claims

1. A method for fabricating an anode for an electrochemical energy storage device, said process comprising the following: a) mixing silicon particles and at least one polymer to form a mixture; b) coating said mixture onto a copper current collector to form a coated copper current collector; and c) subjecting said coated copper current collector to a heat treatment to form said anode A method comprising.

2. The method according to claim 1, wherein the step of subjecting the coated copper current collector to the heat treatment comprises heating the coated copper current collector to a temperature in the range of about 200°C to about 600°C in an inert atmosphere.

3. The method according to claim 1, further comprising adding a solvent to the mixture to disperse the silicon particles and the at least one polymer after step a) and before step b), wherein the solvent is N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), dimethyl sulfone (DMSO ２ ), dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMAc), ethylene carbonate (EC), and propylene carbonate (PC), and is selected from the group consisting of.

4. The method according to claim 3, further comprising removing the solvent from the mixture coated on the copper current collector after step b) and before step c).

5. The method according to claim 3, wherein in step c), the solvent is removed from the mixture coated on the copper current collector.

6. The method according to claim 1, wherein the silicon particles range in size from about 1 nm to about 100 μm.

7. The method according to claim 1, wherein said mixture comprises one or more carbonaceous materials.

8. The method according to claim 7, wherein said one or more carbonaceous materials are selected from graphite, hard carbon, tin, and germanium particles mixed with active material silicon particles.

9. The method according to claim 1, wherein said mixture comprises 10 to 80% by weight of silicon particles.

10. The method according to claim 1, wherein said anode comprises 10 to 40% by weight of polymer.

11. The method according to claim 1, wherein said at least one polymer comprises polyacrylonitrile (PAN).

12. The method according to claim 1, wherein said silicon particles comprise silicon composite particles.

13. A dual electrolyte, comprising the following: (a) 10 to 30 wt.% of the electrolyte of LiPF ６ and LiFSI lithium salts; b) an aprotic organic solvent system containing 10 to 30 wt.% of fluoroethylene carbonate in said electrolyte; and c) at least one additive An electrolyte comprising.

14. The non-aqueous organic solvent system of claim 13, wherein the non-aqueous organic solvent system comprises an open-chain or cyclic carbonate, a carboxylic acid ester, a nitrite, an ether, a sulfone, a ketone, a lactone, a dioxolane, a glyme, a crown ether, a siloxane, a phosphate ester, a phosphite, a monophosphazene or a polyphosphazene, or a mixture thereof.

15. The electrolyte according to claim 13, wherein the non-aqueous organic solvent system is present at a concentration of 40 to 90 wt.% of the electrolyte.

16. The electrolyte according to claim 13, wherein the at least one additive is a compound containing at least one unsaturated carbon-carbon bond, a carboxylic anhydride, a sulfur-containing compound, a phosphorus-containing compound, a boron-containing compound, a silicon-containing compound, a nitrogen-containing compound, or a mixture thereof.

17. The electrolyte according to claim 13, wherein the at least one additive is present at a concentration of 0.1 to 5 wt.% of the electrolyte.

18. An anode, wherein the anode is a current collector coated with a plurality of active material particles, each of the plurality of active material particles having a particle size between about 1 nm and about 100 μm, and at least one polymer, and the plurality of active material particles being surrounded by at least one polymer.

19. An electrochemical energy storage device, wherein the electrochemical energy storage device is an anode including a plurality of active material particles, each of the plurality of active material particles having a particle size between about 1 nm and about 100 μm, and at least one polymer, and the plurality of active material particles being surrounded by the at least one polymer; a cathode; A dual salt electrolyte comprising LiPF ６ and a non-aqueous organic solvent system containing at least one solvent including a lithium salt of LiFSI and fluoroethylene carbonate, and at least one additive, the dual salt electrolyte An electrochemical energy storage device comprising.

20. The electrochemical energy storage device according to claim 19, wherein the plurality of active material particles are silicon particles.

21. The electrochemical energy storage device according to claim 19, wherein the anode comprises one or more of graphite, hard carbon, tin, and germanium particles mixed with the plurality of active material particles.

22. The electrochemical energy storage device according to claim 19, wherein the at least one polymer comprises polyacrylonitrile (PAN).

23. The LiPF ６ and LiFSI lithium salts are present in the range of 10 to 30 wt.% of the electrolyte, and the fluoroethylene carbonate is present in the range of 10 to 30 wt.% of the electrolyte. The electrochemical energy storage device according to claim 19.

24. The electrochemical energy storage device according to claim 19, wherein the cathode comprises a lithium metal oxide, spinel, olivine, olivine coated with carbon, vanadium oxide, lithium peroxide, sulfur, polysulfide, lithium monofluoride, or a mixture thereof.

25. The electrochemical energy storage device according to claim 19, wherein the cathode is a transition metal oxide material and comprises an excess lithium oxide material.

26. The electrochemical energy storage device according to claim 19, further comprising a porous separator that separates the anode and the cathode from each other.

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