Silicon nanocomposite anode

Abstract

A silicon polymer nanocomposite anode including: an anode active material, at least one conductive additive, a binder, and at least one binder additive; a method of preparing the silicon polymer nanocomposite anode; an anode ink useful for preparing the silicon polymer nanocomposite anode; and batteries including the silicon polymer nanocomposite anode.

Description

SILICON NANOCOMPOSITE ANODECROSS-REFERENCE TO REEATED APPLICATIONS[1] The present application claims priority from U.S. Provisional Patent Application No. 63 / 593,017, filed on October 25, 2023, which is hereby incorporated by reference in its entirety.TECHNICAL FIELD[2] The present disclosure generally relates to electrochemical energy storage devices, specifically secondary batteries. More particularly, the present disclosure relates to anodes for use in batteries, such as lithium-ion batteries, and methods of preparing an anode ink, fabricating anodes for batteries, and / or methods of preparing components or materials for the use in anodes of batteries.BACKGROUND[3] Lithium-ion based batteries are one of the promising energy storage technologies with its wide range of applications in different sectors (e.g., electric vehicles, telecom, wireless devices etc.). Their ability to provide high energies and long cycle life is one of the major advantages for its high demand. Tenable performance metrics of lithium-ion batteries (LIBs), pertaining to anode and cathode chemistries has made it a promising energy storage device for any applications. Present day commercial batteries are equipped with graphite anode and layered cathode like NMC811 (LiNi0.8Mn0.1Co0.1O2), with possible energy storage up to —180 Wh / kg with average potential of 3 8 V, which is more than 5 times better than lead-acid batteries) ! ]. Though graphite is the commercially used anode material for the Li ion battery, a lot of research has been going on to modify the anode material of the batteries. Group TVB materials (Si, Ge, Sn, Sb etc.) are one of such materials due to its high theoretical capacity and low lithium interaction voltage[2-3]. With a high theoretical capacity of 4200 mAh / g, silicon has been engendered as a promising anode material for next generation LIBs, as a replacement for graphite. However, silicon generally suffers from enormous volume change (in the order of 300%) during the lithiation and de-lithiation processes, causing cracking and pulverization of active materials, followed by disintegration of the anode and leading to rapid degradation of capacity. Silicon suffers anisotropic volume expansion and pulverization during battery cycling. Upon lithiation, both amorphous Si (a-Si) and crystalline Si (c-Si) anodes first become amorphous and may later form a metastable Li15Si4crystalline phase below -0.05 V versus Li. To avoid this anisotropic volume expansion and hence capacity fading researchers identified various approaches like Si- nanostructures to relieve thestress at the surfaces, which provide necessary void space for expansion, and carbon coatings. Main limitations of silicon-based anodes in Li ion battery are the increase in the silicon in the anode active material, the volume expansion and the impedance in the system which impedes the conducting network. This leads to the capacity fading in the cell[2-3]. Binder in the Si anode should be be flexible and should facilitate the transport of the mobile lithium-ion for better first coulombic efficiency and capacity retention[4-5]. In addition to the binder the anode engineering, which includes the specific formulation of the different components, the slurry coating parameters, the testing conditions plays a major role in the silicon anode performance. In this invention we have developed a suitable anode material with suitable formulation, fabricated anodes to realize the high capacity and high retention in both half-cell and full-cell.[4] There is thus a need for improved anodes that address at least some of the problems described above.SUMMARY[5] In a first aspect, provided herein is a silicon polymer nanocomposite (Si / PNC) anode comprising: an anode active material, at least one conductive additive, a binder, and at least one binder additive.[6] In certain embodiments, the anode active material is selected from the group consisting of silicon / graphite composite, SiOx / carbon composite, Si / SiOx / carbon composite, graphite, silicon, Si / SiC composite, SiC, and mixtures thereof.[7] In certain embodiments, the at least one conductive additive is selected from the group consisting of acetylene black, carbon black, graphite, conducting graphite, carbon nanoparticles, graphene, graphene quantum dots, graphene oxide, graphene nanoribbons, carbon nanofibers, boron nitride, phosphorene, and combinations thereof.[8] In certain embodiments, the binder is selected from the group consisting of polyvmylidene difluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (Na-CMC), styrene-butadiene rubber (SBR), sodium alginate, a crosslinked chitosan, wherein the crosslinked chitosan comprises chitosan and at least one phosphate salt or a conjugate acid thereof, wherein the at least one phosphate salt is selected from the group consisting of orthophosphate metal salts, pyrophosphate metal salts, polyphosphate metal salts, adenosine diphosphate metal salts, uridine diphosphatemetal salts and thymidine diphosphate metal salts, polyacrylic acid, poly(3,4- ethylenedioxythiophene) (PEDOT), and combinations thereof.[9] In certain embodiments, the Si / PNC anode further comprises an organic acid selected from the group consisting of citric acid, acetic acid, polyacrylic acid, 2-methyl acrylic acid, malic acid, lactic acid, formic acid, oxalic acid, uric acid, tartaric acid, butyric acid, folic acid, succinic acid, and combinations thereof.

[0010] In certain embodiments, the at least one binder additive is selected from the group consisting of a metal salt, a metal, and a ceramic-based compound.

[0011] In certain embodiments, the metal salt is selected from the group consisting of MOH, SnX2, MNO3, M2SO4, M2PO4, M3PO4, M4P2O7, M5P3O7, M2CO M3, M2Ti3O7, MOAc, and combinations thereof, wherein M is Li+, Na+, K+, or NH4+; and X is a halide.

[0012] In certain embodiments, the metal is tin nanoparticles or silver nanoparticles.

[0013] In certain embodiments, the ceramic-based compound is Li4Ti5O12, Na4Ti50i2, NbjOj, or a MXene.

[0014] In certain embodiments, the at least one conductive additive is selected from the group consisting of acetylene black, carbon black, graphite, conducting graphite, carbon nanoparticles, graphene, graphene quantum dots, graphene oxide, graphene nanoribbons, carbon nanofibers, boron nitride, and combinations thereof; the binder is selected from the group consisting of polyvinylidene difluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF- HFP), carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (Na-CMC), styrenebutadiene rubber (SBR), sodium alginate, a crosslinked chitosan, wherein the crosslinked chitosan comprises chitosan and at least one phosphate salt or a conjugate acid thereof, wherein the at least one phosphate salt is selected from the group consisting of orthophosphate metal salts, pyrophosphate metal salts, polyphosphate metal salts, adenosine diphosphate metal salts, uridine diphosphate metal salts and thymidine diphosphate metal salts, polyacrylic acid, poly(3,4- ethylenedioxythiophene) (PEDOT), and combinations thereof; the at least one binder additive is selected from the group consisting of MOH, SnX2, MNO3, M2SO4, M2PO4, M3PO4, M4P2O7, M5P3O7, M2CO3, M2Ti3O7, MOAc, tin nanoparticles, silver nanoparticles, Li4Ti5O12, Na4TisOi2, Nb2O5, a MXene and combinations thereof, wherein M is Li+, Na+, K+, or NH4+; and X is a halide.

[0015] In certain embodiments, the Si / PNC anode further comprises an organic acid selected from the group consisting of citric acid, acetic acid, polyacrylic acid, 2-methyl acrylic acid, malic acid,lactic acid, formic acid, oxalic acid, uric acid, tartaric acid, butyric acid, folic acid, succinic acid, and combinations thereof.

[0016] In certain embodiments, the at least one conductive additive is selected from the group consisting of acetylene black, carbon black, graphite, conducting graphite, carbon nanoparticles, graphene, graphene quantum dots, graphene oxide, graphene nanoribbons, carbon nanofibers, boron nitride, and combinations thereof; the binder is a crosslinked chitosan, wherein the crosslinked chitosan comprises chitosan and at least one phosphate salt or a conjugate acid thereof, wherein the at least one phosphate salt is selected from the group consisting of orthophosphate metal salts, pyrophosphate metal salts, polyphosphate metal salts, adenosine diphosphate metal salts, uridine diphosphate metal salts and thymidine diphosphate metal salts; and wherein the at least one binder additive is selected from the group consisting of MOH, SnXz, MNO3, M2SO4, M2PO4, M3PO4, M4P2O7, M5P3O7, M2CO3, M2Ti3O7, MOAc, tin nanoparticles, silver nanoparticles, Li4Ti5O12, Na4Ti5O12. Nb2O5. a MXene and combinations thereof, wherein M is Li+, Na+, K+, or NH4+; and X is a halide.

[0017] In certain embodiments, the at least one phosphate salt is selected from the group consisting of orthophosphate metal salts, tripolyphosphate metal salts, and adenosine diphosphate metal salts, and the at least one binder additive comprises tin nanoparticles, MOH, SnX2, Nb2O5, a MXene and combinations thereof, wherein M is Li+, Na+, K+, or NH4+; and X is a halide

[0018] In certain embodiments, the Si / PNC anode further comprising an organic acid selected from the group consisting of citric acid, acetic acid, polyacrylic acid, 2-methyl acrylic acid, malic acid, lactic acid, formic acid, oxalic acid, uric acid, tartaric acid, butyric acid, folic acid, succinic acid, and combinations thereof.

[0019] In certain embodiments, the crosslinked chitosan comprises lithium phosphate, sodium tripolyphosphate, or disodium adenosine diphosphate.

[0020] Tn certain embodiments, the at least one binder additive comprises tin nanoparticles, MOH, SnX2, Nb2O5, or a MXene .

[0021] In certain embodiments, the at least one binder additive comprises tin nanoparticles, LiOH, SnCl2, Nb2O5, or a MXene.

[0022] In certain embodiments, the active anode material is a silicon / graphite composite; and the at least one conductive additive is carbon black.

[0023] In certain embodiments, the anode active material, the least one conductive additive, the binder, and the at least one binder additive have a mass ratio of 30-80:10-50:5-19.5:0.05-5, respectively.

[0024] In certain embodiments, the active anode material is a silicon / graphite composite; the at least one conductive additive is carbon black, the binder is chitosan, the at least one binder additive comprises tin nanoparticles, LiOH, SnCl2, Nb2O5, or a MXene, and the anode active material, the least one conductive additive, the binder, and the at least one binder additive have a mass ratio of 30-80: 10-50:5-19.5:0.05-5, respectively.

[0025] In certain embodiments, the active anode material is a silicon / graphite composite; the at least one conductive additive is carbon black, the binder is a crosslinked chitosan, wherein the crosslinked chitosan comprises chitosan and at least one phosphate salt or a conjugate acid thereof, wherein the at least one phosphate salt is lithium phosphate, sodium tripolyphosphate, or disodium adenosine diphosphate, the at least one binder additive comprises and the anode active material, the least one conductive additive, the binder, and the at least one binder additive have a mass ratio of 30-80:10-50:5-19.5:0.05-5, respectively.

[0026] In a second aspect, provided herein is a method of preparing the Si / PNC anode describe ed herein, the method of comprising: combining chitosan and an organic acid thereby forming a chitosan salt; combining the chitosan salt and at least one phosphate salt selected from the group consisting of orthophosphate metal salts, pyrophosphate metal salts, polyphosphate metal salts, adenosine diphosphate salts, uridine diphosphate salts and thymidine diphosphate salts thereby forming the crosslinked chitosan salt; combining the crosslinked chitosan salt, active anode material, the at least one conductive additive, and the at least one binder additive selected from the group consisting of a metal salt, a metal, and a ceramic-based compound thereby forming an anode ink; and optionally curing the anode ink thereby forming the Si / PNC anode.

[0027] In certain embodiments, each of combining chitosan and the organic acid, combining the chitosan salt and the at least one phosphate salt and combining the crosslinked chitosan salt, active anode material, the at least one conductive additive, and the at least one binder additive are conducted in an aqueous solvent.

[0028] In certain embodiments, combining the crosslinked chitosan salt, active anode material, the at least one conductive additive, and the at least one binder additive comprises high shear rate mixing.

[0029] In certain embodiments, combining the chitosan salt and the at least one phosphate salt thereby forming the crosslinked chitosan salt is conducted at a pH less than 7.BRIEF DESCRIPTIONS OF DRAWINGS

[0030] The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated and understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings.

[0031] Figure 1. Different components for anode ink preparation in accordance with certain embodiments described herein.

[0032] Figure 2. Exemplary schematic diagram of a method for preparing an anode in accordance with certain embodiments described herein.

[0033] Figure 3. Cycle life performance of Si / PNC vs. Li half cells cycled at 0.1 C, with chitosan-TPP as the binder.

[0034] Figure 4. Cycle life performance of Si / PNC vs. LiCoCb full cell cycled at 0.1 C, with chitosan-TPP as the Si / PNC binder.

[0035] Figure 5. Cycle life performance of Si / PNC vs. Li half cell, with chitosan-TPP as the binder and metallic Sn nanoparticle as the binder additive.

[0036] Figure 6. Cycle life performance of Si / PNC vs. Li half cell, with chitosan-TPP as the binder, and LiOH and SnCL as the binder additives.

[0037] Figure 7. Cycle life performance of Si / PNC vs. Li half cell cycled at 1 C, with chitosan- TPP as the binder and SnCL as the binder additive.

[0038] Figure 8. Cycle life performance of Si / PNC vs. Li half cells, with chitosan-TPP as the binder, and (a) without any binder additive, and (b) with LiOH as the binder additive tested at same cycling protocol.

[0039] Figure 9. Cycle life performance of Si / PNC vs. Li half cell cycled at 1 C, with chitosan- ADP as the binder.

[0040] Figure 10. Cycle life performance of Si / PNC vs. Li half cell cycled at 1 C, with chitosan- Li3PO4as the binder.

[0041] Figure 11. Cycle life performance of Si / PNC vs. LiFePO4full cell cycled at 1 C, with chitosan-LiiPO4 as the binder.

[0042] Figure 12. Cycle life performance of Si / PNC vs. Li half cell cycled at 1 C, with chitosan- TPP as the binder and MXene as the binder additive.

[0043] Figure 13. An exemplary battery configuration according to certain embodiments described herein.DETAILE DESRIPTION

[0044] Definitions

[0045] Throughout the present disclosure, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. It is also noted that in this disclosure and particularly in the claims and / or paragraphs, terms such as “comprises”, “comprised”, “comprising” and the like can have the meaning attributed to it in U.S. Patent law, e.g., they can mean “includes”, “included”, “including”, and the like; and that terms such as “consisting essentially of’ and “consists essentially of’ have the meaning ascribed to them in U.S. Patent law, e.g., they allow for elements not explicitly recited, but exclude elements that are found in the prior art or that affect a basic or novel characteristic of the present invention.

[0046] Furthermore, throughout the present disclosure and claims, unless the context requires otherwise, the words “include”, “comprise” or variations such as “includes”, “including” “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers.

[0047] The use of the singular herein includes the plural (and vice versa) unless specifically stated otherwise. In addition, where the use of the term "about" is before a quantitative value, the present teachings also include the specific quantitative value itself, unless specifically stated otherwise. As used herein, the term "about" refers to a ±10%, ±7%, ±5%, ±3%, ±1%, or ±0% variation from the nominal value unless otherwise indicated or inferred.

[0048] The present disclosure provides a Si / PNC anode comprising an anode active material, at least one conductive additive, a binder, and at least one binder additive.

[0049] The anode active material can be any anode active material known in the art. In certain embodiments, the anode active material comprises a metal selected from Groups IA, IIA, I1IB and IVB of the Periodic Table of the Elements and compounds capable of forming intermetallic compounds and allows with metals selected from Groups IA, IIA, IIIB and IVB of the Periodic Table of the Elements. Examples of these anode active materials include lithium, sodium, potassium and their alloys and compounds capable of forming intermetallic compounds and alloys with lithium, sodium, potassium. Examples of suitable alloys include, but are not limited to, Li-Si, Li-Al, Li-B, Li-Si-B. Examples of suitable intermetallic compounds include, but are not limited to, intermetallic compounds that include or consist of two or more components selected from the group consisting of Li, Ti, Cu, Sb, Mn, Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn and La. Other examples of suitable intermetallic compounds include, but are not limited to, intermetallic compounds that comprise lithium metal and one or more components selected from the group consisting of Ti, Cu, Sb, Mn, Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, and La. Other suitable anode active materials include lithium titanium oxides such as Li^isOn, silica alloys, and mixtures of the above anode active materials. The anode active material may be a graphite-based material, such as natural graphite, artificial graphite, coke, and carbon fiber; a compound containing at least one element such as Al, Si, Sn, Ag, Bi, Mg, Zn, In, Ge, Pb, and Ti, which can alloy with lithium, sodium, or potassium; a composite composed of the compound containing at least one element which can alloy with lithium, sodium, or potassium, the graphitebased material, and carbon; or a lithium-containing nitride; and combinations thereof.

[0050] In certain embodiments, the anode active material is silicon nanoparticles, monocrystalline silicon nanoparticles, monocrystalline silicon nanoflakes, silicon powder, silicon oxide, silicon oxide nanoparticles, SiOxparticles, wherein x is 0.1 to 1.9, silicon nanotubes, silicon nanowires, tin nanopowder, tin oxide nanopowder, and combinations thereof. In certain embodiments, the anode active material comprises silicon. Exemplary anode active materials include, but are not limited to, silicon / graphite composite, SiOx / carbon composite, Si / SiOx / carbon composite, silicon, graphite, Si / SiC composite, SiC, and mixtures thereof. In alternative embodiments, the anode active material comprises graphite. In certain embodiments, the anode active material comprises silicon / graphite composite.

[0051] In certain embodiments, the average particle size of the anode active material ranges from 20-500 nm, 50-500 nm, 100-500 nm, 150-500 nm, 200-500 nm, 250-500 nm, 300-500 nm, 350-500 nrn, 400-500 nrn, 450-500 nm, 20-450 nm, 20-400 nm, 20-350 nm, 20-300 nrn, 20-250 nrn, 20-200 nm, 20-150 nm, 20-100 nm, 20-50 nm, 50-450 nm, 100-400 nm, 150-350 nm, 200-300 nm, 250-300 nm, or 200-250 nm.

[0052] The at least one conducting additive can be a carbon conducting additive, a polymer conducting additive, a metal conducting additive, or a combination thereof. Suitable carbon conducting additive include, but are not limited to, natural graphite, artificial graphite, carbon fiber, carbon nano fibers, carbon black, acetylene black, Ketjen black, carbon nanotubes, graphene, graphene oxide, and combinations thereof. In certain embodiments, the conducting additive is a carbon conducting agent selected from the group consisting of carbon black nanopowder, carbon nanoparticles, double-walled carbon nanotubes, 3D graphene foam, graphene monolayer, graphene multilayer, graphene nanoplatelets, graphene oxide monolayer, graphene oxide paper, graphene oxide thin film, graphite nanofibers, graphite powder, graphite rods, and combinations thereof, a conducting polymer additive selected from the group consisting of poly acetylene, polypyrrole, poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS), polyaniline, polyparaphenylene vinylene, polyisothianaphthalene, polyparaphenylene sulphide, polyparaphenylene, and combinations thereof; or a conducting metal additive selected from the group consisting of copper, nickel, aluminium, silver, and the like. In certain embodiments, the at least one conductive additive can be acetylene black, carbon black, graphite, conducting graphite, carbon nanoparticles, graphene, graphene quantum dots, graphene oxide, graphene nanoribbons, carbon nanofibers, boron nitride, phosphene, or combinations thereof. In certain embodiments, the at least one conductive additive comprises carbon black.

[0053] Generally, all types of conducting additives (including metal fibers, metal powders, graphite powders, carbon nanomaterials) can be used as conductive additives, but compared to metal fiber or metal powder, carbon nanomaterials have superior properties such as low weight, high chemical inertia and high specific surface area. Therefore, the most used conductive additives in lithium ion batteries are carbon nanomaterials, such as carbon black, Super P, acetylene black, carbon nanofibers, and carbon nanotubes. An ideal electrode for a lithium ion battery should have high electronic and ionic conduction. The electronic conduction depends on the electronic conductance of the electrode. The ionic conduction depends on the ionic diffusion which is closely related to the pores in the cathode. The porous structure, especially mesoporous structure canabsorb and retain electrolyte solution, allowing intimate contact between the lithium ions and electrode active material.

[0054] Compared with single conductive additives, multiple conductive additives can take advantage of two or more conductors, which can result in synergistic effects. Therefore, multiple conductive additives usually show some superiority over single conductive additives. For example, carbon black (CB) adheres on the surface of the cathode active material to enhance the conductivity of the cathode active material and CNF couples the cathode active material. Therefore, multiple conductive additives usually show some superiority over single conductive additives. Micro-sized graphite is easily dispersed with cathode active materials, but may not form a good conductive network when using small amounts. When nano-sized Super P or like is also added, a good conductive network can be formed resulting in a cathode that can have improved cyclic life and higher discharge capacity.

[0055] The binder can be selected from the group consisting of PVDF, poly(vinylidene fluoride- PVDF-HFP, CMC, Na-CMC, SBR, sodium alginate, a crosslinked chitosan, wherein the crosslinked chitosan comprises chitosan and at least one phosphate salt or a conjugate acid thereof, wherein the at least one phosphate salt is selected from the group consisting of orthophosphate metal salts, pyrophosphate metal salts, polyphosphate metal salts, adenosine diphosphate metal salts, uridine diphosphate metal salts and thymidine diphosphate metal salts, polyacrylic acid, PEDOT, and combinations thereof. In certain embodiments, the binder comprises crosslinked chitosan.

[0056] Chitosan’s properties can be influenced by a number of parameters, such as its molecular weight and degree of deacetylation (representing the ratio of 2-ammo-2-deoxy-d-glucopyranose to 2-acetamido-2-deoxyd-glucopyranose structural units in the chitosan). The degree of deacetylation of the chitosan used in the binders described herein can range from 0% to 100%. In certain embodiments, the degree of deacetylation of the chitosan used in the binders described herein is greater than 1%, greater than 5%, greater than 10%, greater than 20%, greater than 30%, greater than 40%, greater than 50%, greater than 60%, greater than 70%, greater than 80%, greater than 90%, greater than 95%, greater than 97%, greater than 98%, greater than 99%, or greater than 99.9%. In certain embodiments, the degree of deacetylation of the chitosan used in the binders described herein is between 50 - 100 %, 60 - 99 %, 65 - 99 %, 65 - 99 %, 65 - 99 %, 70 - 99 %,75 - 99 %, or 75 - 95 %. In certain embodiments, the degree of deacetylation of the chitosan used in the binders described herein is between 75 - 95 %.

[0057] The chitosan can have a molecular weight of 10,000 - 1,000,000 Da. In certain embodiments, the chitosan can have a molecular weight of 10,000 - 500,000; 20,000 - 500,000; 30,000 - 500,000; 40,000 - 500,000; 40,000 - 450,000; or 40,000 - 400,000 Da. In certain embodiments, the chitosan can be low molecular weight (molecular weight 50,000 - 190,000 Da), medium molecular weight chitosan (molecular weight 190,000 - 310,000 Da); or high molecular weight chitosan (molecular weight 310,000 - 375,000 Da).

[0058] Chitosan can exist as a polycationic polymer, which is well known for its chelating properties. Therefore, interactions with negatively charged components, such as phosphate metal salts, can lead to the formation of a network ionically phosphate crosslinked chitosan chains. Ionic interactions between the negative charges of the phosphate and positively charged groups of chitosan are thought to be the major molecular interactions inside the crosslinked network. The formation of the network ionically phosphate crosslinked chitosan chains can be prepared by combining cationic chitosan and at least one phosphate salt; or in the alternative by combining neutral chitosan with the conjugate acid of at least one phosphate salt. Consequently, the binder compositions comprising chitosan contemplated herein encompass binder compositions comprising chitosan and at least one crosslinking agent (e g., MNO3, M2SO4, M2PO4, M3PO4, M4P2O7, M5P3O7, M2CO3, MiTisCh, MO Ac, and combinations thereof, wherein M is Li+, Na+, K+, or NH4+; and X is a halide, and / or an organic acid described herein).

[0059] Binders described herein can comprise chitosan and at least one phosphate salt selected from the group consisting of orthophosphate metal salts (M2PO4), pyrophosphate metal salts (M4P2O7), tripolyphosphate metal salts (M5P3O7), polyphosphate metal salts (M4P2O7(MPO3)m, wherein m is 2, 3, 4, 5, 6, 7, 8, 9, or 10) and organic diphosphate metal salts. In certain embodiments, the binder has 1, 2, 3, 4, or more different types of phosphate salts.

[0060] Polyphosphate metal salts suitable for use in the binder described herein include, but are not limited to, linear polyphosphate metal salts, metaphosphate metal salts, and branched polyphosphate metal salts. Exemplary polyphosphate metal salts include, but are not limited to, tripolyphosphate salts, tetraphosphate salts, pentaphosphate salts, trimetaphosphate salts, tetrametaphosphate salts, and the like.

[0061] The at least one phosphate salt can comprise any metal cation. Exemplary metal cations include one or more cations selected from Group 1 and Group 11 of the Periodic Table of the Elements. In certain embodiments, the at least one phosphate salt can comprise one or more metal cations selected from the group consisting of Li+, Na+, K+, Mg2+, and Ca2+. In certain embodiments, the at least one phosphate salt is a sodium orthophosphate, sodium pyrophosphate, or a sodium polyphosphate. In certain embodiments, the at least one phosphate salt is sodium tripolyphosphate. The binder can also comprise chitosan and at least one phosphate salt conjugate acid selected from the group consisting of conjugate acids of orthophosphate, pyrophosphate, and polyphosphate.

[0062] Conjugate acids of orthophosphate, pyrophosphate, and polyphosphate suitable for use in the binder described herein include, but are not limited to, linear polyphosphoric acids, metaphosphoric acids, and branched polyphosphoric acids. Exemplary polyphosphoric acids include, but are not limited to, triphosphoric acids, tetraphosphoric acids, pentaphosphoric acids, trimetaphosphoric acid, tetrametaphosphoric acids, and the like. In certain embodiments, the conjugate acid of the phosphate salt is polyphosphoric acid (CAS Number: 8017-16-1).

[0063] The conjugate acids of orthophosphate, pyrophosphate, and polyphosphate can comprise one or more ionizable protons and thus can exist in one or more conjugate acid protonation states. In instances in which the binder composition comprises a conjugate acid of orthophosphate, pyrophosphate, or polyphosphate, the conjugate acid can be in any of the possible protonation states of the phosphate salts described herein or a combination thereof. For example, conjugate acids of PO42' (orthophosphate) include HPO42', H2PO4-, and H3PO4; and conjugate acids of P3O105' (tripolyphosphate) include HP3O104-, H2P3O103-, H3P3O102'-, H4P3O101'-, and H5P3O10. Anionic conjugate acids of the phosphate salts can comprise any one or more of the metal cations described herein

[0064] Organic diphosphate metal salts suitable for use as binder additives include, but are not limited to, adenosine diphosphate metal salts, uridine diphosphate metal salts, and thymidine diphosphate metal salts. In certain embodiments, the organic diphosphate metal salt is sodium adenosine diphosphate.

[0065] The binder may comprise the at least one phosphate salt or a conjugate acid thereof and chitosan in a 1 :1 to 1 : 10,000 mass ratio. In certain embodiments, the binder comprises the at least one phosphate salt and chitosan in a 1: 1 to 1 :10,000; 1 : 1 to 1 :5,000; 1 : 1 to 1: 1,000; 1: 1 to 1 :500; 1 : 1 to 1 :250; 1 : 1 to 1 : 100; 1 : 1 to 1 :20; 1 : 1 to 1 : 10; 1 :5 to 1 : 10; 1 :6 to 1 : 10; 1 :7 to 1 : 10; 1 :7 to 1 :9;1:8 to 1 :9; 1 :9 to 2:3; 1 :9 to 3:7: or 1 :5 to 1 :3.33 mass ratio. In certain embodiments, the binder comprises less than 1 part by weight of the at least one phosphate salt to 4 parts by mass of chitosan. In certain embodiments, the binder comprises the at least one phosphate salt in a mass ratio of less than 1 part by mass of the at least one phosphate salt to 5 parts by mass of chitosan; less than 1 part by mass of the at least one phosphate salt to 6 parts by mass of chitosan; less than 1 part by mass of the at least one phosphate salt to 7 parts by mass of chitosan; less than 1 part by mass of the at least one phosphate salt to 8 parts by mass of chitosan; or less than 1 part by mass of the at least one phosphate salt to 9 parts by mass of chitosan. In the examples below, the binder comprises the at least one phosphate salt and chitosan in a 1 :5 to 1 :3.33 mass ratio.

[0066] In certain embodiments, the Si / PNC anode further comprises an organic acid selected from the group consisting of citric acid, acetic acid, polyacrylic acid, 2-methyl acrylic acid, malic acid, lactic acid, formic acid, oxalic acid, uric acid, tartaric acid, butyric acid, folic acid, succinic acid, and combinations thereof.

[0067] The at least one binder additive can be selected from the group consisting of a metal salt, a metal, a ceramic-based compound, and combinations thereof.

[0068] Exemplary metal salts include, but are not limited to, MOH, 811X2, MNO3, M2SO4, M2PO4, M3PO4, M4P2O7, M5P3O7, M2CO3, M2Ti3O7, MO Ac, and combinations thereof, wherein M is Li+, Na+, K+, or NH4+; and X is a halide. Tn certain embodiments, the metal salt is LiOH, SnCl2, Li3PO4, NasPiO?, or a mixture thereof.

[0069] The metal can be tin nanoparticles, silver nanoparticles, or a mixture thereof.

[0070] The ceramic-based compound is Li4Ti5O12, Na4TisOi2, Nb2O5, or a MXene.

[0071] MXenes can be described by a chemical formula of Mn-iXnTxor M2M’nXn+iTx, wherein n = 1, 2 or 3; M and M’ can be a transition metal, such as an M is an early transition metal; X can be C and / or N; and Txis one or more surface functional groups that can be selected from O, OH, F, and Cl Exemplary Mxenes include, but are not limited to, Ti2CTx, Ti2NTx, Ti3C2Tx, V2CTX, Cr2CTx, MO2CTX, MO3C2TX, Nb2CTxand Ta2CTx.

[0072] In certain embodiments, the at least one binder additive comprises one or more of , M2PO4, M4P2O7, and M5P3O7; and at least one of MOH, SnX2, MNO3, M2SO4, M2CO3, M2Ti2O7, MOAc, tin nanoparticles, silver nanoparticles, Li4Ti5O12, Na4Ti5O12, Nb2O5, and a MXene. In certain embodiments, the at least one binder additive comprises MOH, SnX2, Nb2O5, or a MXene. Incertain embodiments, the at least one binder additive comprises at least one of LiOH, SnCl2, Nb2O5. and a MXene.

[0073] The anode active material can be present in the Si / PNC anode at 1-90 wt%, 10-90 wt%, 20-90 wt%, 30-90 wt%, 40-90 wt%, 50-90 wt%, 60-90 wt%, 70-90 wt%, 80-90 wt%, 30-80 wt%, 30-70 wt%, 30-60 wt%, 30-50 wt%, 30-40 wt%, 40-80 wt%, 50-80 wt%, 60-80 wt%, or 70-80 wt% relative to the weight of the anode active material, the least one conductive additive, the binder, and the at least one binder additive.

[0074] The at least one conductive additive can be present in the Si / PNC anode at 10-60 wt%, 10- 50 wt%, 10-40 wt%, 10-30 wt%, 10-20 wt%, 20-60 wt%, 30-60 wt%, 40-60 wt%, 50-60 wt%, 20- 50 wt%, or 30-40 wt% relative to the weight of the anode active material, the least one conductive additive, the binder, and the at least one binder additive.

[0075] The binder can be present in the Si / PNC anode at 1-30 wt%, 1-25 wt%, 1-20 wt%, 1-15 wt%, 1-10 wt%, 1-5 wt%, 5-19.5 wt%, 10-19.5 wt%, 15-19.5 wt%, 5-15 wt%, or 5-10 wt% relative to the weight of the anode active material, the least one conductive additive, the binder, and the at least one binder additive.

[0076] The at least one binder additive can be present in the Si / PNC anode at 0.01-10 wt%, 0.01-9 wt%, 0.01-8 wt%, 0.01-7 wt%, 0.01-6 wt%, 0.01-5 wt%, 0.01-4 wt%, 0.01-3 wt%, 0.01-2 wt%, 0.01 -1 wt%, 0.05-10 wt%, 0.5-10 wt%, 1-10 wt%, 2-10 wt%, 3-10 wt%, 4-10 wt%, 5-10 wt%, 6-10 wt%, 7-10 wt%, 8-10 wt%, 9-10 wt%, 0.5-5 wt%, 1-5 wt%, 2-5 wt%, 3-5 wt%, or 4-5 wt% relative to the weight of the anode active material, the least one conductive additive, the binder, and the at least one binder additive.

[0077] In certain embodiments, the anode active material, the least one conductive additive, the binder, and the at least one binder additive have a mass ratio of 30-80:10-50:5-19.5:0.05-5, respectively.

[0078] In another aspect, provided herein is an anode ink comprising the least one conductive additive, the binder, the at least one binder additive, optionally the organic acid, and at least one solvent.

[0079] The solvent may be an aqueous solvent, a polar organic solvent, or a mixture thereof. Suitable polar organic solvents include, but are not limited to, alcohols, alkyl halides, dialkylformamides, dialkyl ketones, dialkyl sulfoxides, tertiary amides, and combinations thereof. Exemplary polar organic solvents include, but are not limited to, methanol, ethanol, isopropanol,dimethylformamide (DMF), dimethylsulfoxide (DMSO), dimethylacetamide (DMA), acetone, methyl ethyl ketone, and N-methyl-2-pyrrolidone (NMP). The organic acid may be acetic acid, propionic acid, formic acid, lactic acid, oxalic acid, succinic acid, tartaric acid, malic acid, benzoic acid, methylsulfonic acid, phenylsulfonic acid, toluenesulfonic acid, or a combination thereof

[0080] The solid content of the anode ink can range from 10-50 wt%, 20-50 wt%, 30-50 wt%, 40- 50 wt%, 10-40 wt%, 10-30 wt%, 10-20 wt%, 20-40 wt%, 30-40 wt%, or 20-30 wt%.

[0081] The present disclosure also provides a method of preparing the Si / PNC anode described herein, the method of comprising: combining chitosan and an organic acid thereby forming a chitosan salt; combining the chitosan salt and at least one phosphate salt or a conjugate acid thereof, wherein the at least one phosphate salt is selected from the group consisting of orthophosphate metal salts, pyrophosphate metal salts, polyphosphate metal salts, adenosine diphosphate metal salts, uridine diphosphate metal salts and thymidine diphosphate metal salts thereby forming a crosslinked chitosan salt; combining the crosslinked chitosan salt, active anode material, the at least one conductive additive, and the at least one binder additive selected from the group consisting of a metal salt, a metal, and a ceramic-based compound thereby forming an anode ink; and optionally curing the anode ink thereby forming the Si / PNC anode.

[0082] The anode link can be coated on a substrate, such as a current collector and cured thereby forming the Si / PNC anode. Curing can be accomplished by any known method, such as by heating and / or exposure to vacuum. In some embodiments, the coating may be performed using on or more methods selected from the group consisting of screen printing, spray coating, coating using a doctor blade, Gravure coating, dip coating, silk screen, painting, and coating using a slot die, depending on the viscosity of the slurry.

[0083] Combining the crosslinked chitosan salt, active anode material, the at least one conductive additive, and the at least one binder additive can be accomplished by any method known in the art.

[0084] In certain embodiments, combining the crosslinked chitosan salt, active anode material, the at least one conductive additive, and the at least one binder additive comprises shear mixing, magnetic stirring, planetary ball milling, centrifugal mixing, and / or kneader mixing. In certain embodiments, combining the crosslinked chitosan salt, active anode material, the at least one conductive additive, and the at least one binder additive comprises high shear rate mixing.

[0085] In certain embodiments, combining the chitosan salt and the at least one phosphate salt thereby forming the crosslinked chitosan salt is conducted at a pH less than 7, less than 6, less than5, less than 4, less than 3, less than 1, or less than 1. In certain embodiments, combining the chitosan salt and the at least one phosphate salt thereby forming the crosslinked chitosan salt is conducted at a pH of 0-6.5, 0-6, 0-5, 0-4, 0-3, 0-2, 0-1, 1-6, 1-5, 1-4, 1-3, 1-2, 2-5, 2-4, or 3-4.

[0086] In certain embodiments, provided herein is a lithium battery comprising: the Si / PNC anode described herein; a cathode disposed opposite to the Si / PNC anode; and an electrolyte disposed between the Si / PNC anode and the cathode.

[0087] Figure 14 depicts an exemplary battery configuration according to certain embodiments described herein, comprising the Si / PNC anode 103; the cathode 101 disposed opposite to the Si / PNC anode 103; and an electrolyte 102 disposed between the Si / PNC anode and cathode 101.

[0088] The lithium battery can be of any type known in the art. Exemplary batteries include, but are not limited to, coin cell, cylindrical cell (including 18650 cells), pouch cell, and prismatic cell.

[0089] Suitable cathode include, but are not limited to, lithium transition metal oxides. The lithium transition metal oxide can include elements in addition to lithium, one or more transition metals and oxygen or can consist of lithium, one or more transition metals and oxygen. In instances where the lithium transition metal oxide includes cobalt as a transition metal, the lithium transition metal oxide can include more than one transition metal. In some instances, the lithium transition metal oxide excludes cobalt. The transition metal in the lithium transition metal oxide can include or consist of one or more elements selected from the group consisting of Li, Al, Mg, Ti, B, Ga, Si, Mn, Zn, Mo, Nb, V, Ag, Ni, and Co. Suitable lithium transition metal oxides include, but are not limited to, LixVOy, LiCoC2, LiNiC2, LiNi1-xCoy MezO2, LiMn0.5Ni0.5O2, LiMn13Co1 / 3Ni1 / 3O2, LiFeO2, LizMyyO4, wherein Me is one or more transition metals selected from Li, Al, Mg, Ti, B. Ga, Si, Mn, Zn, Mo, Nb, V, Ag and combinations thereof and M is one or more transition metals such as Mn, Ti, Ni, Co, Cu, Mg, Zn, V, and combinations thereof. In some instances, 0<x<l before initial charge of the battery and / or 0<y<l before initial charge of the battery and / or x' is >0 before initial charge of the battery and / or 1 -x'+y+z=l and / or 0 8<Z<1 .5 before initial charge of the battery and / or 1.5<yy<2.5 before initial charge of the battery.

[0090] Additional examples of cathodes include LiCoO2. LiNiO2, LiNi1-xCoyMezOz, LiMn0.5N0.5io5O2, LiMn(1 / 3)Co(1 / 3Ni(1 / 3)O2, and LiNiCoyAlzO2.

[0091] Any electrolyte known in the art can be used in the lithium battery described herein. In certain embodiments, the electrolyte is a lithium salt-containing non-aqueous electrolyte. Forexample, the non-aqueous electrolyte may be a non-aqueous liquid electrolyte, an organic solid electrolyte, or an inorganic solid electrolyte.

[0092] The non-aqueous liquid electrolyte can comprise at least one electrolyte solvent selected from propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate (DMC), diethyl carbonate, methyl ethyl carbonate (MEC), fluoroethylene carbonate (FEC), y- butyrolactone, methyl formate, methyl acetate, 1,2-dimethoxy ethane, tetrahydrofuran, 2- methyltetrahydrofuran, dimethyl sulfoxide, 1,3 -dioxolane, formamide, dimethylformamide, dioxane, acetonitrile, nitromethane, ethyl monoglyme, phosphoric triesters, trimethoxymethane, di oxolane derivatives, sulfolane, 3-methyl-2-oxazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethyl ether, 1,3-propanesultone, N-methyl acetamide, acetonitrile, acetals, ketals, sulfones, sulfolanes, aliphatic ethers, cyclic ethers, glymes, polyethers, phosphate esters, siloxanes, dioxolanes, and N-alkylpyrrolidones. In certain embodiments, the non-aqueous liquid electrolyte comprises EC, DMC, DEC, EMC, FEC, and combinations thereof.

[0093] Non-limiting examples of the organic solid electrolyte are polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphoric acid ester polymers, poly agitation lysine, polyester sulfide, polyvinyl alcohols, polyvinylidene fluoride, and polymers containing ionic dissociation groups.

[0094] Non-limiting examples of the inorganic solid electrolyte are nitrides, halides, sulfates, and silicates of lithium, such as Li3N, Lil, Li5NL, Li3N-Lil-LiOH, LiSiO4, LiSiO4-LiI-LiOH, Li3SiS3, Li4S1O4, Li4SiO4-LiI-LiOH, and Li3PO4-Li2S-SiS2.

[0095] The lithium salt may be any lithium salt that is in common use for lithium batteries, for example, any lithium salt that is soluble in the above-mentioned non-aqueous electrolytes. For example, the lithium salt may be at least one of LiCl, LiBr, Lil, L1CIO4. LiBF4, LiBioClio, LiPFg, LiCF3SO3, L1CF3CO2, LiAsF6, LiSbF6, L1AICI4, CH3SO3L1, CF3SO3L1, (CF3SO2)2NLi, lithium chloroborate, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate, LiNO3, lithium bisoxalatoborate, lithium oxalyldifluoroborate, and lithium bis(trifluoromethanesulfonyl)imide.

[0096] Exemplary electrolytes include, but are not limited to, LiPF6in EC:DMC=1 : 1 Wt%; EC:DEC:EMC=1: 1: 1 Vol%; EC:DEC=1:1 Vol% with 5.0% FEC; EC:DMC:DEC=1:1:1 Vol%; EC:DMC:EMC=1:1:1 Wt%; EC:DEC=1:1 Vol%; EC:DMC=1:1 Vol% with 5.0% FEC; EC:DEC=1:1 Wt%; EC:EMC=3:7 Vol%; EC:DMC:EMC=1 : 1 : 1 Vol%; and EC:DMC=1:1 Vol%.

[0097] Examples

[0098] Example 1

[0099] In an exemplary embodiment, Si / PNC anode was prepared by mixing active material, carbon black and the crosslinked chitosan-tripolyphosphate (TPP) polymer binder in the weight percentage ratios of 50:30:20, respectively. In a typical procedure to prepare a 20 mL anode slurry, the chitosan-TPP binder was prepared by adding 0.080 g of sodium tripolyphosphate and 0.21 g of acetic acid into 19.8 g of deionized water and was mixed until fully dissolved. 0.40 g of chitosan powder was then added into the aqueous mixture and was further mixed until dissolved. 1.0 g of Si / PNC powder and 0.60 g of carbon black were then added and mixed until all the Si / PNC and carbon black is completely dissolved. All mixing was done in a high shear rate mixing equipment and at room temperature. The resulting slurry was coated on copper foil and dried at 80 °C under ambient condition for 30 min, and then under vacuum at 130 °C for 3-4 h. The dried electrodes were then calendared and used for the fabrication of lithium-ion cells. The Si / PNC half-cell was assembled against Li metal as a counter electrode. Celgard was used as the separator and the IM LiTFSI in combination of carbonate-based solvents (EC / DMC / EMC / FEC) were used as electrolyte. The cell data was recorded in the range of 0.01-1.5 V vs. Li / Li+. Further, the Li metal was replaced by LiCoO2cathode for full cell measurement. The cell was tested in the voltage range of 3-4.3 V The L1CoO2cathode was obtained commercially.

[0100] Figure 3 shows the discharge capacity as a function of cycle number for the Si / PNC anode half-cell. Referring to Figure 3, the Si / PNC anode delivered an average reversible specific capacity of 1,800 mAh / g and retained more than 83% of its initial capacity after 1,500 cycles when cycled at 0.1 C. Figure 4 shows the cycle life performance of Si / PNC in full cell vs. LiCoO2cathode. Specific capacity of 170 mAh / g was obtained for the Si / PNC vs. LiCoO2full cell cycled at 0.1 C. After 500 cycles, a 98% capacity retention was recorded.

[0101] Example 2

[0102] Tn a second example, Si / PNC was mixed with conducting carbon black the chitosan- tripolyphosphate (TPP) binder and metallic Sn nanoparticle as a binder additive in the weight percentage ratios of 60:20: 18:2, respectively. In a typical procedure to prepare a 20 mL anode slurry, stoichiometric amount of S / / PNC, Sn nanoparticles and sodium tripolyphosphate was mixed in 19.8 mL of deionized water until fully dissolved. Conductive carbon black and acetic acid were added sequentially and mixed until dissolved. Finally, chitosan powder was then added into the mixture and was mixed until all powders were completely dissolved. The chitosan-acetic acid ratiowas kept at 2.2 w / v%. The aqueous slurry was then further mixed for 2 h. All mixing was done in a high shear rate mixing equipment and in room temperature. The resulting slurry was coated on copper foil and dried at 80 °C under ambient condition for 30 min, and then under vacuum at 130 °C for 3-4 h The dried electrodes were then calendared and used for the fabrication of lithium-ion cells. The Si / PNC half-cell was fabricated against Li metal as a counter electrode. Celgard was used as the separator and the IM LiTFSI in combination of carbonate-based solvents (EC / DMC / EMC / FEC) were used as the electrolyte. The cell data was recorded cycled in the range voltage window of 0.01- 1.5V vs. Li / Li+.

[0103] Figure 5 shows cycle life data of the half cell. The cell provides an initial capacity of 1,300 mAh / g, and after 50 cycles, 85% of this initial capacity is retained.

[0104] Example 3

[0105] In a third example, Si / PNC was mixed with conducting carbon black, chitosan tripolyphosphate (TPP) binder with LiOH and SnCl2as binder additives. The weight percentage ratio of the powder mixture was maintained as at 73: 10:10:3.5:3.5, respectively. In a typical procedure to prepare a 20 mL anode slurry, the chitosan- TPP binder was prepared by adding stoichiometric amount of sodium tripolyphosphate, acetic acid, LiOH and SnCl2in 19.8 mL of deionized water and was mixed until dissolved. 0.25 g of chitosan powder was then added into the aqueous mixture and mixed until dissolved, followed by Si / PNC and carbon black. The chitosanacetic acid ratio was kept at 2.2 w / v%. All mixing was done in a high shear rate mixing equipment and in room temperature. The resulting slurry was coated on copper foil and dried at 80 °C under ambient condition for 30 min, and then under vacuum at 100 °C for 3-4 h. The dried electrodes were then calendared and used for the fabrication of lithium-ion cells. The Si / PNC was fabricated against Li metal as a counter electrode. Celgard was used as the separator and the 1 M LiTFSI in combination of carbonate-based solvents (EC / DMC / EMC / FEC) were used as the electrolyte. The cell data was recorded in the voltage window of 0.01 -1 ,5V vs. Li / Li+.

[0106] The Si / PNC showed an initial capacity of 640 mAh / g and retains 90% of this capacity after 80 cycles as shown in Figure 6.

[0107] Example 4

[0108] In a fourth example, Si / PNC was mixed with conducting carbon black, chitosan tripolyphosphate (TPP) binder and SnCl2as additive. The weight percentage ratio of the powder mixture was maintained as at 73:10: 10:7, respectively. In a typical procedure to prepare a 20 Lanode slurry, the chitosan- TPP binder was prepared by adding stoichiometric amount of sodium tripolyphosphate, acetic acid and SnCl2in 19.8 tnL of deionized water and was mixed until dissolved. Chitosan powder was then added into the aqueous mixture and was further mixed until fully dissolved. The chitosan-acetic acid ratio was kept at 2.0 w / v%. Si / PNC powder and carbon black were then added and mixed until all powders were completely dissolved. All mixing was done in a high shear rate mixing equipment and in room temperature. The resulting slurry was coated on copper foil and dried at 80 °C under ambient condition for 30 min, and then under vacuum at 100 °C for 3-4 h. The dried electrodes were then calendared and used for the fabrication of lithium-ion cells. The Si / PNC was fabricated against Li metal as a counter electrode. Celgard was used as the separator and the 1 M LiTFSI in combination of carbonate-based solvents (EC / DMC / EMC / FEC) were used as the electrolyte The cell data was recorded in the voltage window of 0.01 -1.5V vs. Li / Li+.

[0109] The Si / PNC showed an initial capacity of 2, 100 mAh / g and a capacity retention of 72.2% after 100 cycles at 1 C cycling rate as shown in Figure 7.

[0110] Example 5

[0111] In a fifth example, Si / PNC was mixed with conducting carbon black, chitosan tripolyphosphate (TPP) binder and LiOH as the binder additive in the weight percentage ratio of 80: 10:9.92:0.08, respectively. The chitosan-TPP binder was prepared by adding stochiometric amount of sodium tripolyphosphate, acetic acid and LiOH in 19.78 g of deionized water and was mixed until dissolved. 0.4 g of chitosan powder was then added into the aqueous mixture and was further mixed until fully dissolved. The chitosan-acetic acid ratio was kept at 2.2 w / v%. Si / PNC powder was then added and mixed until all powders were completely dissolved. All mixing was done in a high shear rate mixing equipment and in room temperature. The resulting slurry was coated on copper foil and dried at 80 °C under ambient condition for 30 min, and then under vacuum at 110 °C for 3-4 h The dried electrodes were then calendared and used for the fabrication of lithium-ion cells. The Si / PNC was fabricated against Li metal as the counter electrode. Celgard was used as the separator and the IM LiTFSI in combination of carbonate-based solvents (EC / DMC / EMC / FEC) were used as the electrolyte. The cell data was recorded in the range voltage window of 0.01 -1.5V vs. Li / Li+.

[0112] Figure 8 shows the Si / PNC anodes tested with the same cycling protocol with and without the LiOH binder additive. The discharge capacity obtained after 100 cycles for the Si / PNC anodehalf-cell with LiOH binder additive is about 1.5 times higher than that of the anode half-cell without the binder additive. This translates to a capacity retention of 84% for Si / PNC with the LiOH binder additive.

[0113] Example 6

[0114] In the sixth example, Si / PNC was mixed with conducting carbon black and the chitosanadenosine diphosphate (ADP) binder in the weight percentage ratios of 85:7:8, respectively. In a typical procedure to prepare a 10 mL anode slurry, the chitosan- ADP binder was prepared by adding 0.038 g of ADP and 0.10 g of acetic acid in 9.90 g of deionized water and was mixed until dissolved. 0.2 g of chitosan powder was then added into the aqueous mixture and was further mixed until dissolved. The chitosan-acetic acid ratio was kept at 2.2 w / v%. 2.13 g of Si / PNC and 0.18 g of carbon black were then added and mixed until fully dissolved The aqueous mixture was then mixed to provide homogeneity. All mixing was done in a high shear rate mixing equipment and in room temperature. The resulting slurry was coated on copper foil and dried at 80 °C under ambient condition for 30 min, and then under vacuum at 130 °C for 3-4 h. The dried electrodes were then calendared and used for the fabrication of lithium-ion cells. The Si / PNC half-cell was fabricated against Li metal as a counter electrode. Celgard was used as the separator and the 1 M LiPFs in combination of carbonate-based solvents (EC / DMC / EMC / FEC) were used as the electrolyte. The cell data was recorded cycled in the range voltage window of 0.01 -1 .5V vs. Li / Li+.

[0115] The Si / PNC mixed with chitosan- ADP binder delivered a capacity of 780 mAh / g when cycled at 0.5 C, as shown in Figure 9. After 80 cycles at 1 C, the half cell retained 76% of its initial capacity.

[0116] Example 7

[0117] In the seventh example, Si / PNC was mixed with conducting carbon black and chitosan- Lr.PO-i binder. The weight percentage ratio of the powder mixture was maintained at 85:7:8, respectively. In a typical procedure to prepare a 30 mL anode slurry, the chitosan-Li3PCL binder was prepared by adding 0.18 g of LiiPCL and 0.31 g of acetic acid in 29.7 g of deionized water. 0.6 g of chitosan powder was then added into the aqueous mixture and was further mixed until all powder were fully dissolved. The chitosan-acetic acid ratio was kept at 2.2 w / v%. 6.19 g of Si / PNC and 0.53 g of carbon black powders was then added and mixed until completely dissolved. The resulting slurry was coated on copper foil and dried at 80 °C under ambient condition for 30 min, and then under vacuum at 130 °C for 3-4 h The dried electrodes were then calendared and usedfor the fabrication of lithium-ion cells. The Si / PNC was fabricated against Li metal as a counter electrode. Celgard was used as the separator and the 1 MLiPF6in combination of carbonate-based solvents (EC / DMC / EMC / FEC) were used as the electrolyte. The cell data was recorded in the voltage window of 0.01 -1.5V vs Li / Li-H Tn a full cell, the Li metal was replaced by LiFePCL cathode and the cell was cycled in the voltage range of 2.0-4.0 V The LiFePCL cathode was obtained commercially.

[0118] As shown in Figure 10, this Si / PNC with chitosan-LLPCL binder delivered an initial capacity of 580 mAh / g at 1 C. The half cell retained 88% of this initial capacity after 100 cycles. In full cell vs. LiFePO4in Figure 11, a first cycle capacity of 120 mAh / g was achieved at 0.5 C, and after 40 cycles, it retained 72% of the initial capacity.

[0119] Example 8

[0120] In the eighth example, Si / PNC was mixed with conducting carbon black, chitosantripolyphosphate (TPP) polymer binder and MXene as binder additive. The weight percentage ratio of the powder mixture was maintained at 84:7:8:1, respectively. In a typical procedure to prepare 10 mL of the anode slurry, the chitosan- TPP binder with MXene additive was prepared by adding stochiometric amount of sodium tripolyphosphate and acetic acid in 9.89 mL of deionized water and was mixed until dissolved. MXene was then added into the mixture and was mixed until fully dissolved. Chitosan powder was then added into the aqueous mixture and was further mixed. The chitosan-acetic acid ratio was kept at 2.0 w / v%. The Si / PNC and conducting carbon black powders were then added and were mixed until all powders were completely dissolved. All mixing was done in a high shear rate mixing equipment. The resulting slurry was coated on copper foil and dried at 80 °C under ambient condition for 30 min, and then under vacuum at 130 °C for 3-4 h. The dried electrodes were then calendared and used for the fabrication of lithium-ion cells. The Si / PNC was fabricated against Li metal as a counter electrode. Celgard was used as the separator and the IM LiPL, in combination of carbonate-based solvents (EC / DMC / EMC / FEC) were used as the electrolyte. The cell data was recorded in the voltage window of 0.01-1.5V vs. Li / Li+.

[0121] Figure 12 presents the capacity retention data for the Si / PNC prepared with chitosan-TPP binder with MXene additive. The initial capacity obtained was 510 mAh / g. After 100 cycles at 1 C, the capacity recorded was 470 mAh / g, resulting in a capacity retention of 92%.

[0122] Example 9

[0123] In the ninth example, Si / PNC was mixed with conducting carbon black, chitosan- tripolyphosphate (TPP) polymer binder and Nb2O5as binder additive. The weight percentage ratio of the powder mixture was maintained at 89:4:6: 1, respectively. In a typical procedure to prepare a 5 mL anode slurry, the chitosan-TPP binder with Nb2O5additive was prepared by adding 0.002 g of sodium tripolyphosphate and 0.053 g of acetic acid in 4.95 g of deionized water and was mixed until dissolved. 0.017 g of Nb2O5was then added into the mixture and was mixed until fully dissolved. 0.1 g of chitosan powder was then added, followed by 1.48 g of Si / PNC and 0.067 g of carbon black. The chitosan-acetic acid ratio was kept at 2.0 w / v%. The aqueous mixture was then mixed until all powders were completely dissolved. All mixing was done in a high shear rate mixing equipment. The resulting slurry was coated on copper foil and dried at 80 °C under ambient condition for 30 min, and then under vacuum at 130 °C for 3-4 h. The dried electrodes were then calendared and used for the fabrication of lithium-ion cells. The Si / PNC was fabricated against Li metal as a counter electrode. Celgard was used as the separator and the IM LiPFg in combination of carbonate-based solvents (EC / DMC / EMC / FEC) were used as the electrolyte. The cell data was recorded in the voltage window of 0.01-1.5V vs. Li / Li+.

[0124] Figure 13 presents the capacity retention data for the Si / PNC prepared with chitosan-TPP binder with Nb2O5additive. The initial capacity obtained was 570 mAh / g. After 100 cycles at 1 C, the capacity recorded was 419 mAh / g, resulting in a capacity retention of 73.5%.

[0125] ELECTROCHEMICAL TESTING

[0126] Coin cells (2032) were assembled for half-cell studies with the electrode comprising silicon-based anode, metallic lithium as counter electrode and microporous separator.

[0127] The electrolyte used for testing half cells and full cells comprises different lithium salts (LiPF6, LiClO4, LiTFSI, etc) of concentration of 1.0-3.02 M dissolved in suitable organic solvents of a fixed volume or weight ratio (solvent mixture of ethylene carbonate (EC) and / or dimethyl carbonate (DMC) and / or ethyl methyl carbonate (EMC) and / or diethylene carbonate (DEC), with some wt.% amount of electrolyte additives (vinylene carbonate (VC), and / or fluoroethylene carbonate (FEC), and / or LiBOB, and / or LiDFOB, and / or trimethyl phosphite (TMP), and / or triethyl phosphite (TEP)). For example, the electrolyte solution can comprise 1.5 M LiClO4in EC / EMC / DMC (1: 1:1 v / v) with 5 wt.% VC and and / or 5 wt.% FEC.

[0128] Lithium-containing oxide compounds (e.g., LiCoO2, LiNixMn>CozO2with x + y + z = 1, LiNixCoyAlzO2with x + y + z= l)) or lithium hthium-contammg phosphate polyamon compounds (e.g., LiFePC4LiMnFePO4, Li3V2(PO4)3LiMnSiO4) ) were used as cathode.

Claims

What is claimed is:

1. A silicon polymer nanocomposite (Si / PNC) anode comprising: an anode active material, at least one conductive additive, a binder, and at least one binder additive.

2. The Si / PNC anode of claim 1 , wherein the anode active material is selected from the group consisting of silicon / graphite composite, SiOx / carbon composite, Si / SiOx / carbon composite, graphite, silicon, Si / SiC composite, SiC, and mixtures thereof.

3. The Si / PNC anode of claim 1, wherein the at least one conductive additive is selected from the group consisting of acetylene black, carbon black, graphite, conducting graphite, carbon nanoparticles, graphene, graphene quantum dots, graphene oxide, graphene nanoribbons, carbon nanofibers, boron nitride, phosphorene, and combinations thereof.

4. The Si / PNC anode of claim 1, wherein the binder is selected from the group consisting of polyvinylidene difluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF- HFP), carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (Na-CMC), styrenebutadiene rubber (SBR), sodium alginate, a crosslinked chitosan, wherein the crosslinked chitosan comprises chitosan and at least one phosphate salt or a conjugate acid thereof, wherein the at least one phosphate salt is selected from the group consisting of orthophosphate metal salts, pyrophosphate metal salts, polyphosphate metal salts, adenosine diphosphate metal salts, uridine diphosphate metal salts and thymidine diphosphate metal salts, polyacrylic acid, poly(3,4- ethylenedioxythiophene) (PEDOT), and combinations thereof.

5. The Si / PNC anode of claim 1 further comprising an organic acid selected from the group consisting of citric acid, acetic acid, polyacrylic acid, 2-methyl acrylic acid, malic acid, lactic acid, formic acid, oxalic acid, uric acid, tartaric acid, butyric acid, folic acid, succinic acid, and combinations thereof.

6. The Si / PNC anode of claim 1, wherein the at least one binder additive is selected from the group consisting of a metal salt, a metal, and a ceramic-based compound.

7. The Si / PNC anode of claim 6, wherein the metal salt is selected from the group consisting of MOH, SnX2, MNO3, M2SO4, M2PO4, M3PO4, M4P2O7, M5P3O7, M2CO3, M2Ti3O7, MOAc, and combinations thereof, wherein M is Li+, Na+, K+, or NH4+; and X is a halide.

8. The Si / PNC anode of claim 6, wherein the metal is tin nanoparticles or silver nanoparticles.

9. The Si / PNC anode of claim 6, wherein the ceramic-based compound is Li4Ti5O12Na4Ti5O12, Nb2O5. or a MXene.

10. The Si / PNC anode of claim 1 , wherein the at least one conductive additive is selected from the group consisting of acetylene black, carbon black, graphite, conducting graphite, carbon nanoparticles, graphene, graphene quantum dots, graphene oxide, graphene nanoribbons, carbon nanofibers, boron nitride, and combinations thereof; the binder is selected from the group consisting of polyvinylidene difluoride (PVDF), poly(vinylidene fluoride-co- hexafluoropropylene) (PVDF-HFP), carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (Na-CMC), styrene-butadiene rubber (SBR), sodium alginate, a crosslinked chitosan, wherein the crosslinked chitosan comprises chitosan and at least one phosphate salt or a conjugate acid thereof, wherein the at least one phosphate salt is selected from the group consisting of orthophosphate metal salts, pyrophosphate metal salts, polyphosphate metal salts, adenosine diphosphate metal salts, uridine diphosphate metal salts and thymidine diphosphate metal salts, polyacrylic acid, poly(3,4-ethylenedioxythiophene) (PEDOT), and combinations thereof; the at least one binder additive is selected from the group consisting of MOH, SnX2, MNO3, M2SO4, M2PO4, M3PO4, M4P2O7, M5P3O7, M2CO3, M2Ti3O7, MOAc, tin nanoparticles, silver nanoparticles, Li4Ti5O1,2Na4Ti5O2, Nb2O5a MXene and combinations thereof, wherein M is Li+, Na+, K+, or NFU+; and X is a halide.

11. The Si / PNC anode of claim 10 further comprising an organic acid selected from the group consisting of citric acid, acetic acid, polyacrylic acid, 2-methyl acrylic acid, malic acid, lactic acid, formic acid, oxalic acid, uric acid, tartaric acid, butyric acid, folic acid, succinic acid, and combinations thereof.

12. The Si / PNC anode of claim 1, wherein the at least one conductive additive is selected from the group consisting of acetylene black, carbon black, graphite, conducting graphite, carbon nanoparticles, graphene, graphene quantum dots, graphene oxide, graphene nanoribbons, carbon nanofibers, boron nitride, and combinations thereof; the binder is a crosslinked chitosan, wherein the crosslinked chitosan comprises chitosan and at least one phosphate salt or a conjugate acid thereof, wherein the at least one phosphate salt is selected from the group consisting of orthophosphate metal salts, pyrophosphate metal salts, polyphosphate metal salts, adenosine diphosphate metal salts, uridine diphosphate metal salts and thymidine diphosphate metal salts; and wherein the at least one binder additive is selected from the group consisting of MOH, SnX2, MNO3, M2SO4, M2PO4, M3PO4, M4P2O7, M5P3O7, M2CO3, M2Ti3O7, MOAc, tin nanoparticles,silver nanoparticles, Li4Ti5O12, Na^isO 12, NbiO, a MXene and combinations thereof, wherein M is Li+, Na+, K“, or NH4+; and X is a halide.

13. The Si / PNC anode of claim 12, wherein the at least one phosphate salt is selected from the group consisting of orthophosphate metal salts, tripolyphosphate metal salts, and adenosine diphosphate metal salts, and the at least one binder additive comprises tin nanoparticles, MOH, SnX2, Nb2O5, a MXene and combinations thereof, wherein M is Li+, Na-, K+, or NH4+; and X is a halide.

14. The Si / PNC anode of claim 12 or 13 further comprising an organic acid selected from the group consisting of citric acid, acetic acid, polyacrylic acid, 2-methyl acrylic acid, malic acid, lactic acid, formic acid, oxalic acid, uric acid, tartaric acid, butyric acid, folic acid, succinic acid, and combinations thereof15. The Si / PNC anode of any one of claims 12-14, wherein the crosslinked chitosan comprises lithium phosphate, sodium tripolyphosphate, or disodium adenosine diphosphate.

16. The Si / PNC anode of claim 12-15, wherein the at least one binder additive comprises tin nanoparticles, MOH, SnX2, Nb2O5-, or a MXene.

17. The Si / PNC anode of claim 12-15, wherein the at least one binder additive comprises tin nanoparticles, LiOH, SnCl2, Nb2O5, or a MXene.

18. The Si / PNC anode of any one of claims 1 -16, wherein the active anode material is a silicon / graphite composite; and the at least one conductive additive is carbon black.

19. The Si / PNC anode of any one of claims 1-17, wherein the anode active material, the least one conductive additive, the binder, and the at least one binder additive have a mass ratio of 30- 80: 10-50:5-19.5:0.05-5, respectively.

20. The Si / PNC anode of claim 1, wherein the active anode material is a silicon / graphite composite; the at least one conductive additive is carbon black, the binder is chitosan, the at least one binder additive comprises tin nanoparticles, LiOH, SnCl2, Nb2O5, or a MXene, and the anode active material, the least one conductive additive, the binder, and the at least one binder additive have a mass ratio of 30-80: 10-50:5-19.5:0.05-5, respectively.

21. The Si / PNC anode of claim 1, wherein the active anode material is a silicon / graphite composite; the at least one conductive additive is carbon black, the binder is a crosslinked chitosan, wherein the crosslinked chitosan comprises chitosan and at least one phosphate salt or a conjugate acid thereof, wherein the at least one phosphate salt is lithium phosphate, sodium tripolyphosphate,or disodium adenosine diphosphate, the at least one binder additive comprises and the anode active material, the least one conductive additive, the binder, and the at least one binder additive have a mass ratio of 30-80: 10-50:5-19.5:0.05-5, respectively.

22. A method of preparing the Si / PNC anode of claim 14, the method of comprising: combining chitosan and an organic acid thereby forming a chitosan salt; combining the chitosan salt and at least one phosphate salt selected from the group consisting of orthophosphate metal salts, pyrophosphate metal salts, polyphosphate metal salts, adenosine diphosphate salts, uridine diphosphate salts and thymidine diphosphate salts thereby forming the crosslinked chitosan salt; combining the crosslinked chitosan salt, active anode material, the at least one conductive additive, and the at least one binder additive selected from the group consisting of a metal salt, a metal, and a ceramic-based compound thereby forming an anode ink; and optionally curing the anode ink thereby forming the Si / PNC anode.

23. The method of claim 22, wherein each of combining chitosan and the organic acid, combining the chitosan salt and the at least one phosphate salt and combining the crosslinked chitosan salt, active anode material, the at least one conductive additive, and the at least one binder additive are conducted in an aqueous solvent.

24. The method of claim 22, wherein combining the crosslinked chitosan salt, active anode material, the at least one conductive additive, and the at least one binder additive comprises high shear rate mixing.

25. The method of claim 22, wherein combining the chitosan salt and the at least one phosphate salt thereby forming the crosslinked chitosan salt is conducted at a pH less than 7.

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