Method of manufacturing negative electrode comprising lithiated silicon oxide of functional polymer and battery comprising circulating lithium ions thereof

Abstract

The present invention relates to a method of manufacturing a negative electrode comprising a lithiated silicon oxide of a functional polymer and a battery of circulating lithium ions comprising the same. A circulating lithium ion battery includes a negative electrode comprising an electroactive material comprising a lithiated low valent silicon oxide (LSO) material, a polymeric binder, and a functional polymer. The negative electrode is made from a precursor mixture comprising an electroactive material comprising a lithiated low-valent silicon oxide (LSO) material, a polymeric binder, a functional polymer, and an aqueous solvent. The LSO material includes a basic compound, and the functional polymer includes an acidic functional group formulated to react with the basic compound in the LSO material to neutralize the pH of the precursor mixture. The precursor mixture is deposited on a substrate to form a precursor layer, and then the aqueous solvent is removed from the precursor layer to form the negative electrode on the substrate.

Description

Technical Field

[0001] The present disclosure relates to a method of fabricating an electrode for a battery pack that cycles lithium ions, and more particularly to a method of fabricating a negative electrode including a silicon oxide-based electroactive material. Background Art

[0002] The information provided in this section is intended to generally introduce the background of the present disclosure. To the extent that the work currently attributed to the inventors is described in this section, and aspects of the specification that may not otherwise be determined to be prior art at the time of filing, are not admitted, either expressly or implicitly, as prior art against the present disclosure.

[0003] A battery pack that cycles lithium ions typically includes a positive electrode, a negative electrode spaced apart from the positive electrode, and an ion-conductive electrolyte that provides a medium for lithium ion conduction between the positive and negative electrodes during discharge and charge of the battery pack. The electrolyte can be formulated to exhibit high ionic conductivity, good thermal stability, a wide electrochemical stability window, and the ability to form an ion-conductive solid electrolyte interface (SEI) on the surface of the negative and / or positive electrode. Electrodes typically have a composite structure that includes an electrochemically active (electroactive) material, a conductive material, and a polymeric binder. Silicon is a desirable electroactive material for the negative electrode due to its high theoretical specific capacity.

[0004] Composite electrodes can be fabricated by depositing a slurry that includes an electroactive material, a conductive material, and a polymeric binder in a solvent in the form of a continuous layer on a substrate, and then removing the solvent. The polymeric binder and solvent are typically selected to avoid undesirable chemical reactions with the electroactive material and to ensure good solubility of the polymeric binder in the solvent. Summary of the Invention

[0005] According to one or more embodiments of the present disclosure, in a method of fabricating a negative electrode for a battery pack that cycles lithium ions, a precursor mixture is deposited on a substrate to form a precursor layer. The precursor mixture includes an electroactive negative electrode material that includes a lithiated low-valence silicon oxide (LSO) material, a polymeric binder, a functional polymer, and an aqueous solvent. The LSO material includes a basic compound. The functional polymer includes an acidic functional group that is formulated to react with the basic compound in the LSO material to neutralize the pH of the precursor mixture. The aqueous solvent is removed from the precursor layer to form the negative electrode on the substrate.

[0006] In an embodiment, the functional polymer may include a poly(carboxylic acid). In such a case, the acidic functional group may include a carboxyl functional group (-C(=O)OH). For example, the functional polymer may include poly(acrylic acid).

[0007] In an embodiment, the functional polymer may include poly(sulfonic acid). In this case, the acidic functional group may include a sulfo functional group (-S(=O) 2 -OH). For example, the functional polymer may include sulfonated poly(phenylene) (sPP), sulfophenylated poly(phenylene) (sPPP), or a combination thereof.

[0008] The functional polymer may be configured to react with lithium ions in the precursor mixture to form a lithium salt of the functional polymer.

[0009] In an embodiment, the lithium salt of the functional polymer may be insoluble in the aqueous solvent, and wherein the lithium salt of the functional polymer may be configured to deposit on the surface of the LSO material to form a physical barrier that prevents a chemical reaction between the LSO material and the aqueous solvent.

[0010] The functional polymer may have a molecular weight greater than or equal to about 10,000 grams per mole and less than or equal to about 400,000 grams per mole.

[0011] The LSO material may have a nanoporous structure including open nanopores, and wherein the size of the functional polymer may be such that the functional polymer can penetrate the open nanopores of the LSO material.

[0012] The polymer binder may include styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (Na-CMC).

[0013] The basic compound may include lithium hydroxide (LiOH), lithium carbonate (LiCO 3 3), or a combination thereof.

[0014] The electroactive negative electrode material may include the LSO material and graphite.

[0015] The precursor mixture may further include a carbon-based electrochemically inactive conductive material.

[0016] In an embodiment, the method may further include preparing the precursor mixture by introducing the LSO material into a solution containing a polymer binder, a functional polymer, and an aqueous solvent.

[0017] In other embodiments, the method may further include preparing the precursor mixture by preparing a first mixture containing the LSO material and the functional polymer, preparing a second mixture containing the polymer binder and the aqueous solvent, and then introducing the first mixture into the second mixture.

[0018] According to one or more embodiments of the present disclosure, in a method of manufacturing a battery pack for cycling lithium ions, a precursor mixture is deposited on a negative electrode current collector to form a precursor layer. The precursor mixture includes an electroactive negative electrode material, a polymer binder, a functional polymer including sulfonated poly(phenylene), and an aqueous solvent. The electroactive negative electrode material includes a lithiated low-valence silicon oxide (LSO) material and optionally graphite. The LSO material includes a basic compound. The functional polymer includes a sulfo functional group (-S(=O) 2 -OH), which is formulated to react with the basic compound in the LSO material to neutralize the pH of the precursor mixture. The aqueous solvent is removed from the precursor layer to form a negative electrode on the negative electrode current collector. The negative electrode and the negative electrode current collector are assembled into a stack, which includes a positive electrode disposed on a positive electrode current collector and a separator sandwiched between opposing facing surfaces of the negative electrode and the positive electrode. The positive electrode contains lithium ions.

[0019] The functional polymer may include sulfophenylated poly(phenylene) (sPPP).

[0020] The functional polymer may be configured to react with lithium ions in the precursor mixture to form a lithium salt of the functional polymer.

[0021] In an embodiment, the lithium salt of the functional polymer may be insoluble in the aqueous solvent. In this case, the lithium salt of the functional polymer may be configured to deposit on the surface of the LSO material to form a physical barrier that prevents a chemical reaction between the LSO material and the aqueous solvent.

[0022] The polymer binder may include styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (Na-CMC).

[0023] A battery pack for cycling lithium ions includes a negative electrode, a positive electrode spaced apart from the negative electrode, and an electrolyte permeating the negative electrode and the positive electrode. The negative electrode contains an electroactive material, a polymer binder, and a functional polymer including a lithium salt of sulfonated poly(phenylene). The electroactive material includes a lithiated low-valence silicon oxide (LSO) material and optionally graphite. The positive electrode includes an electroactive positive electrode material. The electrolyte includes a lithium salt in a polar aprotic organic solvent.

[0024] The functional polymer may include a lithium salt of phenylated sulfonated poly(phenylene). In an embodiment, the functional polymer may be insoluble in water.

[0025] The present invention discloses the following solutions:

[0026] Method for manufacturing a negative electrode of a battery pack for recycling lithium ions, the method comprising:

[0027] Depositing a precursor mixture on a substrate to form a precursor layer, the precursor mixture comprising an electroactive negative electrode material including a lithiated low-valence silicon oxide (LSO) material, a polymer binder, a functional polymer, and an aqueous solvent, the LSO material comprising a basic compound, and the functional polymer comprising an acidic functional group, the acidic functional group being formulated to react with the basic compound in the LSO material to neutralize the pH of the precursor mixture; and

[0028] Removing the aqueous solvent from the precursor layer to form the negative electrode on the substrate.

[0029] Method according to embodiment 1, wherein the functional polymer comprises poly(carboxylic acid), and wherein the acidic functional group comprises a carboxyl functional group (-C(=O)OH).

[0030] Method according to embodiment 2, wherein the functional polymer comprises poly(acrylic acid).

[0031] Method according to embodiment 1, wherein the functional polymer comprises poly(sulfonic acid), and wherein the acidic functional group comprises a sulfo functional group (-S(=O) 2 -OH).

[0032] Method according to embodiment 4, wherein the functional polymer comprises sulfonated poly(phenylene) (sPP), sulfophenylated poly(phenylene) (sPPP), or a combination thereof.

[0033] Method according to embodiment 1, wherein the functional polymer is configured to react with lithium ions in the precursor mixture to form a lithium salt of the functional polymer, wherein the lithium salt of the functional polymer is insoluble in the aqueous solvent, and wherein the lithium salt of the functional polymer is configured to deposit on the surface of the LSO material to form a physical barrier that prevents a chemical reaction between the LSO material and the aqueous solvent.

[0034] Method according to embodiment 1, wherein the functional polymer has a molecular weight greater than or equal to about 10,000 grams per mole and less than or equal to about 400,000 grams per mole.

[0035] Method according to embodiment 1, wherein the LSO material has a nanoporous structure including open nanopores, and wherein the size of the functional polymer is such that the functional polymer can penetrate the open nanopores of the LSO material.

[0036] Embodiment 9. The method according to Embodiment 1, wherein the polymeric binder comprises styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (Na-CMC).

[0037] Embodiment 10. The method according to Embodiment 1, wherein the basic compound comprises lithium hydroxide (LiOH), lithium carbonate (LiCO 3 ) or a combination thereof.

[0038] Embodiment 11. The method according to Embodiment 1, wherein the electroactive negative electrode material comprises the LSO material and graphite.

[0039] Embodiment 12. The method according to Embodiment 1, wherein the precursor mixture further comprises a carbon-based electrochemically inactive conductive material.

[0040] Embodiment 13. The method according to Embodiment 1, further comprising:

[0041] Preparing the precursor mixture by introducing the LSO material into a solution comprising the polymeric binder, the functional polymer, and the aqueous solvent.

[0042] Embodiment 14. The method according to Embodiment 1, further comprising:

[0043] Preparing the precursor mixture by preparing a first mixture comprising the LSO material and the functional polymer, preparing a second mixture comprising the polymeric binder and the aqueous solvent, and then introducing the first mixture into the second mixture.

[0044] Embodiment 15. A method of manufacturing a battery pack with cyclic lithium ions, the method comprising:

[0045] Depositing a precursor mixture on a negative electrode current collector to form a precursor layer, the precursor mixture comprising an electroactive negative electrode material, a polymeric binder, a functional polymer comprising sulfonated poly(phenylene), and an aqueous solvent, the electroactive negative electrode material comprising a lithiated low-valence silicon oxide (LSO) material and optionally graphite, the LSO material comprising a basic compound, and the functional polymer comprising a sulfo functional group (-S(=O) 2 -OH), the sulfo functional group being formulated to react with the basic compound in the LSO material to neutralize the pH of the precursor mixture;

[0046] Removing the aqueous solvent from the precursor layer to form a negative electrode on the negative electrode current collector; and

[0047] Assemble the negative electrode and the negative electrode current collector into a stack, the stack including a positive electrode disposed on a positive electrode current collector and a separator sandwiched between opposing facing surfaces of the negative electrode and the positive electrode, the positive electrode containing lithium ions.

[0048] Aspect 16. The method according to aspect 15, wherein the functional polymer comprises sulfonated phenylated poly(phenylene) (sPPP).

[0049] Aspect 17. The method according to aspect 15, wherein the functional polymer is configured to react with lithium ions in the precursor mixture to form a lithium salt of the functional polymer, wherein the lithium salt of the functional polymer is insoluble in the aqueous solvent, and wherein the lithium salt of the functional polymer is configured to deposit on the surface of the LSO material to form a physical barrier that prevents a chemical reaction between the LSO material and the aqueous solvent.

[0050] Aspect 18. The method according to aspect 15, wherein the polymeric binder comprises styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (Na-CMC).

[0051] A battery pack for cycling lithium ions, the battery pack comprising:

[0052] A negative electrode comprising an electroactive material, a polymeric binder, and a functional polymer comprising a lithium salt of sulfonated poly(phenylene), the electroactive material comprising a lithiated low-valence silicon oxide (LSO) material and optionally graphite;

[0053] A positive electrode spaced apart from the negative electrode and comprising an electroactive positive electrode material; and

[0054] An electrolyte permeating the negative electrode and the positive electrode, the electrolyte comprising a lithium salt in a polar aprotic organic solvent.

[0055] Aspect 20. The battery pack according to aspect 19, wherein the functional polymer comprises a lithium salt of phenylated sulfonated poly(phenylene), and wherein the functional polymer is insoluble in water.

[0056] Further applicable fields of the present disclosure will be apparent from the detailed description, the claims, and the drawings. The detailed description and the specific examples are only intended to illustrate and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The present disclosure is more fully understood from the detailed description and the drawings, in which:

[0058] Figure 1Schematic perspective view of a motor vehicle powered by a battery pack including a plurality of battery pack modules.

[0059] Figure 2 is Figure 1 Schematic cross-sectional view of a portion of one of the battery pack modules, the battery pack module including a plurality of electrochemical cells or battery packs that cycle lithium ions.

[0060] Figure 3 Schematic cross-sectional view of a battery pack that cycles lithium ions, the battery pack including a positive electrode, a negative electrode, a porous separator, and an electrolyte that permeates the positive electrode, the negative electrode, and the porous separator.

[0061] In the figures, reference numerals may be reused to designate similar and / or identical elements. Detailed Description

[0062] The method of the present disclosure can be used to manufacture a battery pack that cycles lithium ions, and the battery pack includes a negative electrode containing lithiated low-valence silicon oxide (LSO) as an electroactive material. During the manufacture of the LSO-containing negative electrode, a precursor mixture containing the LSO material and a functional polymer in an aqueous solvent is deposited on a metal substrate. The functional polymer is formulated to prevent or inhibit an undesirable chemical reaction between the LSO material and the aqueous solvent during the manufacture of the negative electrode. In addition, the functional polymer contains acidic functional groups that can react with basic compounds in the precursor mixture to help neutralize the pH of the precursor mixture, thereby improving the adhesion of the negative electrode to the metal substrate.

[0063] Figure 1 Depicts a motor vehicle 2 powered by an electric motor 4, the electric motor 4 obtaining electrical power from a battery pack 6 including one or more battery pack modules 8. The battery pack modules 8 can be electrically coupled together in a series and / or parallel arrangement to meet the capacity and power requirements of the electric motor 4. The vehicle 2 can be a pure electric vehicle and can be powered entirely by the electric motor 4, or the vehicle 2 can be a hybrid vehicle and can be powered by the electric motor 4 and an internal combustion engine (not shown).

[0064] As Figure 2As shown, each battery pack module 8 includes one or more electrochemical cells or battery packs 10 that cycle lithium ions. In practice, the battery packs 10 in the battery pack module 8 are typically assembled as stacked layers, which include a negative electrode layer 12, a negative electrode current collector 13, a positive electrode layer 14, a positive electrode current collector 15, and a separator layer 16. Each battery pack 10 is defined by the negative electrode layer 12 and the positive electrode layer 14, and the negative electrode layer 12 and the positive electrode layer 14 are spaced apart from each other by the separator layer 16. In practice, the separator layer 16 can be permeated with an electrolyte that provides a medium for lithium ion conduction between the negative electrode layer 12 and the positive electrode layer 14, or the separator layer 16 itself can be used as the electrolyte. The negative electrode layer 12 is disposed on the negative electrode current collector 13 and is in electrical communication with the negative electrode current collector 13, while the positive electrode layer 14 is disposed on the positive electrode current collector 15 and is in electrical communication with the positive electrode current collector 15. As Figure 2 shown, for efficiency, these layers can be stacked such that some of the negative electrode current collectors 13 and some of the positive electrode current collectors 15 are double-sided and include the negative electrode layer 12 or the positive electrode layer 14 on their respective two sides. In such an arrangement, adjacent negative electrode layers 12 and positive electrode layers 14 share a single negative electrode current collector 13 or positive electrode current collector 15, respectively.

[0065] Figure 3 An electrochemical cell or battery pack 20 that cycles lithium ions is depicted. The battery pack 20 can generate current during discharge, which can be used to power a load device (e.g., an electric motor 4), and can be charged by connecting to a power source. Similar to Figure 1 and 2 the battery pack 10 depicted in, in some aspects, the battery pack 20 can be used to power the electric motor 4 of a motor vehicle 2. Additionally or alternatively, the battery pack 20 can be used in other transportation applications (e.g., motorcycles, boats, tractors, buses, motorcycles, mobile homes, campers, tanks, and airplanes), and can be used to power a wide variety of other stationary and / or portable electronic devices, components, and devices used in industrial and other applications, including industrial, residential, and commercial buildings, consumer goods, industrial equipment and machinery, agricultural or farm equipment, and heavy machinery (as non-limiting examples).

[0066] The battery pack 20 includes a negative electrode 22, a positive electrode 24, a separator 26, and an electrolyte 28. The electrolyte 28 provides a medium for lithium-ion conduction between the negative electrode 22 and the positive electrode 24. The negative electrode 22 is disposed on the main surface of a negative electrode current collector 30, while the positive electrode 24 is disposed on the main surface of a positive electrode current collector 32. In practice, the negative electrode current collector 30 and the positive electrode current collector 32 are electrically coupled to a power source or a load 34 (e.g., an electric motor 4) via an external circuit 36. The negative electrode 22 and the positive electrode 24 are formulated to establish an electrochemical potential difference between the negative electrode 22 and the positive electrode 24 when the battery pack 20 is at least partially charged. During discharge of the battery pack 20, the electrochemical potential established between the negative electrode 22 and the positive electrode 24 drives spontaneous reduction and oxidation (redox) reactions within the battery pack 20 and releases lithium ions and electrons at the negative electrode 22. The released lithium ions travel from the negative electrode 22 through the separator 26 and the electrolyte 28 to the positive electrode 24, while the electrons travel from the negative electrode 22 to the positive electrode 24 via the external circuit 36, which generates an electric current. After the negative electrode 22 has been partially or completely depleted of lithium, the battery pack 20 can be charged by connecting the negative electrode 22 and the positive electrode 24 to a power source 34, which drives non-spontaneous redox reactions within the battery pack 20 and releases lithium ions and electrons from the positive electrode 24. Repeated discharge and charge of the battery pack 20 may be referred to herein as a "cycle", and a complete charge event followed by a complete discharge event is considered a complete cycle.

[0067] The negative electrode 22 is formulated to store and release lithium ions to facilitate charging and discharging of the battery pack 20, respectively. The negative electrode 22 may be in the form of a continuous porous material layer disposed on the main surface of the negative electrode current collector 30. The negative electrode 22 includes an electrochemically active (electroactive) material, a polymeric binder, a functional polymer, and an optional conductive material. The electroactive material of the negative electrode 22 may be referred to herein as an "electroactive negative electrode material"

[0068] The electroactive material of the negative electrode 22 is formulated to store and release lithium ions by undergoing reversible redox reactions with lithium during charging and discharging of the battery pack 20. The electroactive material may account for greater than or equal to about 80% by weight of the negative electrode 22, or optionally greater than or equal to about 90% and less than or equal to about 97%, or optionally less than or equal to about 95%.

[0069] The electroactive material of the negative electrode 22 includes a lithiated low-valence silicon oxide (LSO) material. Before the initial charging of the battery pack 20, the LSO material may have the following chemical formula (1):

[0070] Li x SiO y , (1)

[0071] where 0 < x ≤ 2 and 0 < y ≤ 2.

[0072] As an electroactive material, low-valent silicon oxide (SiO x , where 0 < x ≤ 2) can promote the storage of lithium in the negative electrode 22 by alloying with lithium (lithiation) during charging of the battery 20, and can promote the storage of lithium in the negative electrode 22 by alloying with lithium (lithiation) during discharging of the battery 20 from SiO x De-alloying (de-lithiation) releases lithium ions from it. However, during the initial charging of the battery pack 20, lithium ions and SiO x tends to cause undesirable irreversible side reactions, resulting in consumption of active lithium, irreversible capacity loss and low initial coulombic efficiency. It has been found that when SiO x Before incorporation into the negative electrode 22, pre-lithiated SiO x To form LSO material can reduce the lithium and SiO during the initial cycle of the battery pack 20 x The occurrence of undesirable irreversible side reactions between the batteries 20 is reduced, thereby improving the reversible capacity and cycle stability of the battery pack 20.

[0073] In an embodiment, the LSO material may have an open nanoporous structure having open pores (nanopores) having a diameter greater than or equal to about 1 nanometer (nm) and less than or equal to about 100 nm. The LSO material may account for greater than or equal to about 10%, optionally greater than or equal to about 20%, optionally greater than or equal to about 30%, optionally greater than or equal to about 40%, optionally greater than or equal to about 50%, optionally greater than or equal to about 60%, optionally greater than or equal to about 70%, optionally greater than or equal to about 80%, optionally greater than or equal to about 90%, and less than or equal to about 100% by weight of the electroactive material of the negative electrode 22.

[0074] In addition to the LSO material, the negative electrode 22 may include one or more other electroactive materials. Examples of other electroactive negative electrode materials include lithium, lithium-based materials (e.g., alloys of lithium and silicon, aluminum, indium and / or tin), carbon-based materials (e.g., graphite, activated carbon, carbon black, hard carbon, soft carbon and / or graphene), silicon, silicon-based materials (e.g., alloys of silicon and lithium, tin, iron, aluminum and / or cobalt), silicon oxide, tin oxide, aluminum, indium, zinc, germanium, titanium oxide, lithium titanate, and combinations thereof. In an embodiment, the electroactive material of the negative electrode 22 may include a composite of an LSO material and graphite. For example, in an embodiment, the electroactive material of the negative electrode 22 may consist of an LSO material and graphite.

[0075] ​The polymeric binder is electrochemically inactive and is formulated to provide structural integrity to the negative electrode 22 and to assist in adhering the negative electrode 22 to the major surface of the negative electrode current collector 30. To facilitate the fabrication of the negative electrode 22, the polymeric binder can be water-soluble. The polymeric binder can include styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (Na-CMC), sodium alginate, or combinations thereof. In aspects, the polymeric binder can include a mixture of SBR and Na-CMC. The polymeric binder can comprise greater than or equal to about 2% and less than or equal to about 10% by weight of the negative electrode 22.

[0076] A functional polymer is formulated to prevent or inhibit an undesirable chemical reaction between the LSO material and the aqueous solvent included in the precursor mixture used to form the negative electrode 22, as further discussed below. In embodiments, the functional polymer can be insoluble in water. As used herein, the term "functional polymer" refers to a polymer having a functional group (e.g., an acidic functional group) and / or a polymer that performs a specific function, i.e., preventing or inhibiting an undesirable chemical reaction between the LSO material and the aqueous solvent included in the precursor mixture used to form the negative electrode 22. In embodiments, the functional polymer can also prevent or inhibit an undesirable chemical reaction between the LSO material and the organic solvent included in the electrolyte 28 during operation of the battery pack 20.

[0077] The molecular weight of the functional polymer can be selected such that the functional polymer chains are small enough to be able to at least partially penetrate the open nanopores of the LSO material, thereby providing overall protection of the LSO material from undesirable chemical reactions with the aqueous solvent and / or with the electrolyte 28. In embodiments, the functional polymer can have a molecular weight greater than or equal to about 10,000 grams per mole (g / mol) and less than or equal to about 400,000 g / mol, optionally less than or equal to about 300,000 g / mol, optionally less than or equal to about 200,000 g / mol, optionally less than or equal to about 100,000 g / mol, or optionally less than or equal to about 50,000 g / mol.

[0078] The functional polymer may include an acid-functional polymer having an acidic functional group, a lithium salt of the acid-functional polymer, or a combination thereof. As used herein, a lithium salt of an acid-functional polymer is an acid-functional polymer in which at least 25% of the acidic functional groups have lithium ions as counterions, optionally at least 50% of the acidic functional groups contain lithium ions as counterions, or optionally at least 50% of the acidic functional groups have lithium ions as counterions. In an embodiment, the functional polymer may include poly(carboxylic acid), poly(sulfonic acid), a lithium salt of poly(carboxylic acid), a lithium salt of poly(sulfonic acid), or a combination thereof. Examples of poly(carboxylic acid) include poly(acrylic acid) (PAA), poly(methacrylic acid) (PMAA), poly(maleic acid), poly(ethylacrylic acid) (PEAA), poly(propylacrylic acid) (PPAA), poly(4-vinylbenzoic acid) (PVBA), poly(itaconic acid) (PIA), and combinations thereof. Examples of poly(sulfonic acid) include sulfonated aromatic polymers, poly(vinylsulfonic acid) (PVSA), poly(4-styrenesulfonic acid) (PSSA), poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS), poly(3-sulfopropyl methacrylate) (PSPMA), and combinations thereof. In an embodiment, the functional polymer may include poly(acrylic acid) (PAA), lithium poly(acrylate) (Li-PAA), sulfonated poly(phenylene) (sPP), sulfophenylated poly(phenylene) (sPPP), a lithium salt of sulfonated poly(phenylene) (Li-sPP), a lithium salt of sulfophenylated poly(phenylene) (Li-sPPP), or a combination thereof.

[0079] The amount of the functional polymer in the negative electrode 22 may be selected to correspond to the amount of the LSO material in the negative electrode 22. In an embodiment, the functional polymer may account for greater than or equal to about 0.1% and less than or equal to about 5% by weight of the negative electrode 22.

[0080] The conductive material is optional and may be included in the negative electrode 22 to provide a negative electrode 22 having good conductivity. Examples of the conductive material include carbon-based materials, metals (e.g., nickel), and / or conductive polymers. Examples of carbon-based conductive materials include carbon black (CB) (e.g., acetylene black), graphene (e.g., graphene nanosheets, GNP), graphene oxide, carbon nanotubes (CNT) (e.g., single-walled CNT and / or multi-walled CNT), and / or carbon fibers (e.g., carbon nanofibers). Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, and / or polypyrrole. When present, the conductive material may account for greater than or equal to about 0.5% and less than or equal to about 10% by weight of the negative electrode 22.

[0081] The negative electrode 22 may have a thickness greater than or equal to about 30 micrometers (μm), optionally greater than or equal to about 50 μm, optionally greater than or equal to about 70 μm, or optionally greater than or equal to about 100 μm and less than or equal to about 500 μm.

[0082] The positive electrode 24 is configured to store and release lithium ions during discharge and charging of the battery pack 20. The positive electrode 24 may be in the form of a continuous porous layer disposed on the main surface of the positive electrode current collector 32. The positive electrode 24 includes an electroactive material (electroactive positive electrode material), a polymer binder, and optionally a conductive material.

[0083] The electroactive material of the positive electrode 24 can store and release lithium ions by undergoing a reversible redox reaction with lithium at an electrochemical potential higher than that of the electroactive material of the negative electrode 22, such that there is an electrochemical potential difference between the negative electrode 22 and the positive electrode 24. The electroactive material of the positive electrode 24 can include a material capable of undergoing lithium intercalation and deintercalation or a material capable of undergoing a conversion reaction with lithium. In aspects where the electroactive material of the positive electrode 24 includes an intercalation host material that can undergo reversible insertion or intercalation of lithium ions, the electroactive material of the positive electrode 24 can include a lithium transition metal oxide. For example, the electroactive material of the positive electrode 24 can include a layered lithium transition metal oxide represented by the formula LiMeO 2 , an olivine-type lithium transition metal oxide represented by the formula LiMePO 4 , a monoclinic-type lithium transition metal oxide represented by the formula Li 3 Me 2 (PO 4 ) 3 , a spinel-type lithium transition metal oxide represented by the formula LiMe 2 O 4 , a lithium iron phosphate hydroxide or a combination thereof represented by one or both of the following formulas LiMeSO 4 F or LiMePO 4 F, where Me is a transition metal (e.g., Co, Ni, Mn, Fe, Al, V, or a combination thereof). Specific examples of lithium transition metal oxides include LiNi 1-x-y Co x Mn y O 2 (NMC), where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1; LiNi 1-x-y-z Co x Mn y Al z O 2 (NCMA), where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, and 0 ≤ z ≤ 1; LiNi 1-x- y Co x Al y O 2 (NCA), where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1; LiNi x Mn1-x O 2 (LNMO), where 0 ≤ x ≤ 1; lithium manganese oxide (LMO) (e.g., Li (1+x) Mn 2 O 4 , where 0.1 ≤ x ≤ 1); lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O 4 ); lithium cobalt oxide (LiCoO 2 )(LCO); lithium iron phosphate (LiFePO 4 ); lithium vanadium phosphate (LiVPO 4 ); lithium manganese iron phosphate (LiMn 1-x Fe x PO 4 , where 0 ≤ x ≤ 1); lithium-rich manganese layered oxide (LMR); and combinations thereof. In aspects of the electroactive material of the positive electrode 24 including conversion materials, the electroactive material of the positive electrode 24 may include sulfur, selenium, tellurium, iodine, halides (e.g., fluoride or chloride), sulfides, selenides, tellurides, iodides, phosphides, nitrides, oxides, oxysulfides, oxyfluorides, sulfur fluorides, sulfur-oxyfluorides, or lithium and / or its metal compounds (e.g., compounds of iron, manganese, nickel, copper, and / or cobalt).

[0084] The polymeric binder is electrochemically inactive and may be included in the positive electrode 24 to provide the positive electrode 24 with structural integrity and / or to assist the positive electrode 24 in adhering to the main surface of the positive electrode current collector 32. Examples of polymeric binders for the positive electrode 24 include polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), ethylene propylene diene monomer (EPDM) rubber, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), nitrile butadiene rubber (NBR), styrene-butadiene rubber (SBR), styrene-ethylene-butene-styrene copolymer (SEBS), polyacrylate, alginate, polyacrylic acid, and combinations thereof.

[0085] The optional conductive material is electrochemically inactive and may be included in the positive electrode 24 to provide the positive electrode 24 with sufficient conductivity to support the penetration of electrons therethrough. Examples of conductive materials for the positive electrode 24 include carbon-based materials, metals (e.g., nickel), and / or conductive polymers. Examples of carbon-based conductive materials include carbon black (CB) (e.g., acetylene black), graphite, graphene (e.g., graphene nanosheets, GNP), graphene oxide, carbon nanotubes (CNT), and / or carbon fibers (e.g., carbon nanofibers). Examples of conductive polymers for the positive electrode 24 include polyaniline, polythiophene, polyacetylene, and / or polypyrrole.

[0086] The separator 26 is configured to physically and electrically isolate the negative electrode 22 and the positive electrode 24 from each other while allowing lithium ions to pass through. The separator 26 has an open microporous structure and may comprise organic and / or inorganic materials. For example, the separator 26 may include a polymer such as a polyolefin. In an embodiment, the separator 26 may include polyethylene (PE), polypropylene (PP), polyamide (PA), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and / or poly(vinyl chloride) (PVC).

[0087] The electrolyte 28 is ion-conductive and is formulated to provide a medium for lithium ion conduction between the negative electrode 22 and the positive electrode 24. The electrolyte 28 includes an organic solvent and a lithium salt in the organic solvent. The organic solvent may include a non-aqueous polar aprotic organic solvent. Non-limiting examples of non-aqueous polar aprotic organic solvents include cyclic carbonates (e.g., ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), fluoroethylene carbonate (FEC), and vinylene carbonate (VC)); linear carbonates (e.g., dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC)); aliphatic carboxylic esters (e.g., methyl formate, methyl acetate, methyl propionate); lactones (e.g., γ-butyrolactone, γ-valerolactone, and / or δ-valerolactone); nitriles (e.g., succinonitrile, glutaronitrile, and / or adiponitrile); sulfones (e.g., tetramethylene sulfone, ethyl methyl sulfone, vinyl sulfone, phenyl sulfone, 4-fluorophenyl sulfone, benzyl sulfone, and / or sulfolane); aliphatic ethers (e.g., triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dimethoxypropane, 1,2-dimethoxyethane, 1,2-diethoxyethane, and / or ethoxymethoxyethane); cyclic ethers (e.g., 1,4-dioxane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane); phosphate esters (e.g., triethyl phosphate and / or trimethyl phosphate); and combinations thereof. The lithium salt is soluble in the organic solvent and provides a channel for lithium ions to pass through the electrolyte 28. The lithium salt may include an inorganic lithium salt, an organic lithium salt, or a combination thereof. Examples of lithium salts include lithium hexafluorophosphate (LiPF 6 ), lithium difluorophosphate (LiPO 2 F 2 ), lithium perchlorate (LiClO 4 ), lithium tetrachloroaluminate (LiAlCl 4 ), lithium iodide (LiI), lithium bromide (LiBr), lithium thiocyanate (LiSCN), lithium tetrafluoroborate (LiBF 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium trifluoromethanesulfonate (LiCF 3 SO 3 ), lithium bis(trifluoromethane)sulfonimide (LiN(CF 3 SO 2 )2 ) Lithium bis(fluorosulfonyl)imide (LiN(FSO 2 )) (LiSFI), lithium tetraphenylborate (LiB(C 2 H 6 H 5 )) (LiTPB), lithium bis(oxalato)borate (LiB(C 4 O 2 O 4 )) (LiBOB), lithium difluoro(oxalato)borate (LiBF 2 )(C 2 (C 2 O 4 )) (LiDFOB), and combinations thereof.

[0088] The negative electrode current collector 30 and the positive electrode current collector 32 are conductive and provide electrical connections between the external circuit 36 and the negative electrode 22 and the positive electrode 24, respectively. In aspects, the negative electrode current collector 30 and the positive electrode current collector 32 can be made of metal and can be in the form of a non-porous metal foil, a perforated metal foil, a porous metal mesh, or a combination thereof. The negative electrode current collector 30 can be made of copper, nickel, or an alloy thereof, stainless steel, or other suitable conductive materials. The positive electrode current collector 32 can be made of aluminum (Al) or other suitable conductive materials.

[0089] Method

[0090] The negative electrode 22 can be manufactured by depositing a precursor mixture on a metal substrate to form a precursor layer and then drying the precursor layer to form the negative electrode 22 on the metal substrate. In an embodiment, the metal substrate can be made of a material substantially the same as that of the negative electrode current collector 30.

[0091] The precursor mixture includes an electroactive negative electrode material, a polymer binder, a functional polymer, and an optional conductive material in an aqueous solvent (e.g., water). The electroactive negative electrode material, the polymer binder, the functional polymer, and the optional conductive material can be present in the precursor mixture in substantially the same proportions as in the negative electrode 22. The electroactive negative electrode material, the polymer binder, and the optional conductive material included in the precursor mixture can have substantially the same composition as the electroactive negative electrode material, the polymer binder, and the optional conductive material included in the negative electrode 22. Specifically, the electroactive negative electrode material included in the precursor mixture can include LSO material and optionally one or more other electroactive materials.

[0092] The precursor mixture can be prepared by mixing an electroactive negative electrode material, a polymeric binder, a functional polymer, an aqueous solvent, and an optional conductive material. For example, in some embodiments, the precursor mixture can be prepared by introducing an LSO material into a solution comprising a polymeric binder, a functional polymer, and an aqueous solvent. In other embodiments, the precursor mixture can be prepared by preparing a first mixture comprising the LSO material and the functional polymer, preparing a second mixture comprising the polymeric binder and the aqueous solvent, and then introducing the first mixture into the second mixture. In any embodiment, the LSO material is preferably combined with one or more other components of the precursor mixture after, or substantially simultaneously with, the combination of these components with the functional polymer.

[0093] As described above, before incorporating the LSO material into the negative electrode 22, the LSO material can be formed by prelithiation of a low-valence silicon oxide (SiO x ) material, which can help reduce the consumption of active lithium during the initial cycle of the battery pack 20 compared to the amount of active lithium consumed during the initial cycle if the SiO x is not prelithiated. However, it has been found that when the LSO material is in contact with water in the aqueous solvent used to prepare the precursor mixture, an undesirable chemical reaction can occur between the LSO material and the water. For example, when in contact with water, the basic compounds in the LSO material (i.e., lithium salts including LiOH and / or LiCO 3 ) can dissolve and ionize in the aqueous solvent, releasing hydroxide (OH - ) anions (and Li + cations), which can undesirably increase the pH of the precursor mixture. At the same time, lithium (Li) and silicon (Si) in the LSO material can react with water in the aqueous solvent to form LiOH and SiO 2 , respectively, while generating hydrogen gas (H 2 ). The generation of H 2 gas during the preparation of the precursor mixture can pose a safety hazard and can undesirably result in the formation of bubbles and / or pits in the resulting negative electrode 22. In addition, the formation of LiOH and / or SiO 2 from the LSO material can reduce the specific capacity of the negative electrode 22 and can further increase the pH of the precursor mixture. However, it has been found that if the pH of the precursor mixture is too high (e.g., greater than or equal to about 12 or about 13), the negative electrode 22 may not adhere sufficiently to the surface of the metal substrate.

[0094] The functional polymer is formulated to react and / or interact with the LSO material to form a physical barrier on its surface that inhibits or prevents undesirable contact between the LSO material and water in the aqueous solvent during the fabrication of the negative electrode 22. For example, the functional polymer can create a physical barrier on the surface of the LSO material that prevents the basic compounds (e.g., LiOH and / or LiCO 3 ) in the LSO material from reacting with and dissolving in the aqueous solvent, thereby preventing or inhibiting an undesirable increase in the pH of the precursor mixture by the LSO material. As another example, the functional polymer can create a physical barrier on the surface of the LSO material that prevents Li and / or Si in the LSO material from reacting with water in the aqueous solvent and generating H 2 gas, thereby improving the homogeneity and processability of the precursor mixture.

[0095] The functional polymer used to prepare the precursor solution is an acid-functional polymer and contains acidic functional groups that are configured to react with basic compounds (e.g., OH - anions) in the precursor mixture to neutralize the pH of the precursor mixture, thereby improving the adhesion of the negative electrode 22 to the metal substrate. Examples of acidic functional groups include carboxyl (-C(=O)OH), sulfo (-S(=O) 2 -OH), phosphonyl (-P(=O)(-OH) 2 ), nitro (-NO 2), thiol (-SH) and combinations thereof. Examples of acid-functional polymers include poly(carboxylic acids), poly(phosphonic acids), poly(sulfonic acids), poly(amino acids), poly(boric acids) and combinations thereof. Examples of poly(carboxylic acids) include poly(acrylic acid) (PAA), poly(methacrylic acid) (PMAA), poly(maleic acid), poly(ethyl acrylic acid) (PEAA), poly(propyl acrylic acid) (PPAA), poly(4-vinylbenzoic acid) (PVBA), poly(itaconic acid) (PIA) and combinations thereof. Examples of poly(phosphonic acids) include poly(ethylene glycol phosphate acrylate) (PEGAP), poly(vinylphosphonic acid) (PVPA), poly(ethylene glycol methacrylate phosphate) (PEGMP), poly(4-vinyl-benzylphosphonic acid) (PVBPA) and combinations thereof. Examples of poly(sulfonic acids) include sulfonated aromatic polymers, poly(vinyl sulfonic acid) (PVSA), poly(4-styrene sulfonic acid) (PSSA), poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS), poly(3-sulfopropyl methacrylate) (PSPMA), and combinations thereof. Examples of poly(amino acids) include poly(aspartic acid) (PASA), poly(L-glutamic acid) (PLGA), poly(histidine) (PHIS), and combinations thereof. Examples of poly(boronic acids) include poly(vinylphenylboronic acid) (PVPBA), poly(3-acrylamidophenylboronic acid) (PAAPBA), and combinations thereof.

[0096] Specific examples of acid-functional polymers include poly(acrylic acid) (CH 2 -CHC(=O)OH) n , wherein n is the number of repeating units), sulfonated poly(phenylene) (sPP), sulfonated poly(phenylene) (sPPP), and combinations thereof. In embodiments, the ion exchange capacity (IEC) of the acid-functional polymer, which represents the number of basic groups that can be neutralized by the acid-functional polymer, may be greater than or equal to about 2 milliequivalents of H + / g(meq H + / g), optionally greater than or equal to about 3 meq H + / g, or optionally greater than or equal to about 3.7 meq H + / g.

[0097] The functional polymer may be a homopolymer or a copolymer. In embodiments, the functional polymer may include a copolymer and a copolymer of a monomer having no acidic functional group (unsubstituted monomer). For example, the functional polymer may include a copolymer of a sulfonated poly(phenylene) and an unsubstituted poly(phenylene). In some specific examples, the functional polymer may include a copolymer of a sulfonated phenylated poly(phenylene) and an unsubstituted phenylated poly(phenylene).

[0098] ​​When the acidic functional groups in the acid-functional polymer react with the basic compounds (e.g., OH− anions and Li + cations) in the precursor mixture, at least some of the acidic functional groups of the acid-functional polymer are deprotonated, forming a lithium salt of the acid-functional polymer while releasing water. Thus, the functional polymer included in the final negative electrode 22 may or may not include acidic functional groups.

[0099] The acidic functional groups in the acid-functional polymer are hydrophilic and, in some embodiments, can provide good water solubility to the acid-functional polymer. In such cases, in some embodiments, the deprotonation of the acidic functional groups in the acidic functional polymer can result in the formation of a water-insoluble functional polymer. This water-insoluble functional polymer can deposit on the surface of the LSO material, thereby forming a physical barrier on the LSO material that can provide long-term protection to the LSO material against undesired physical and / or chemical interactions with the aqueous solvent in the precursor mixture.

[0100] The precursor mixture prepared without adding the acid-functional polymer has significant gas evolution immediately after mixing, and the gas evolution continues even after the sample is aged. Compared with the precursor mixture that does not include the acid-functional polymer, adding the acid-functional polymer to the precursor mixture results in the formation of a precursor mixture with a relatively low pH. Adding a water-soluble acid-functional polymer to the precursor mixture effectively prevents the generation of bubbles (e.g., H 2 gas) in the precursor mixture, even after aging for about 24 hours. On the other hand, adding an acidic solution (e.g., tannic acid) (without adding the acid-functional polymer) to the precursor mixture is ineffective in preventing or suppressing the generation of bubbles in the precursor mixture, indicating that the acid-functional polymer not only neutralizes the pH of the precursor mixture but also protects the LSO material from unwanted reactions with water in the aqueous solvent.

[0101] When sPPP is used as the acid-functional polymer in the precursor mixture, it can effectively prevent the generation of bubbles in the precursor mixture even after aging for more than 72 hours. On the other hand, when PAA is used as the acid-functional polymer in the precursor mixture, bubble generation occurs after aging the precursor mixture for more than about 24 hours. Without being bound by theory, it is believed that the continuous effectiveness of sPPP in preventing bubble generation is due to the water-insolubility of Li-sPPP in water.

[0102] As an acid-functional polymer, sPPP is water-soluble. However, when at least some of the sulfonic acid functional groups in sPPP react with lithium ions in the precursor mixture and form the lithium salt of sulfonated poly(phenylene) (Li-sPPP), the resulting Li-sPPP is substantially insoluble in water. It is believed that when sPPP is converted to Li-sPPP, Li-sPPP precipitates from the precursor mixture and deposits on the surface of the LSO material. Since Li-sPPP is insoluble in aqueous solvents, Li-sPPP remains on the surface of the LSO material and does not redissolve in the aqueous solvent over time, which is different from Li-PAA, which remains soluble in water upon lithiation and thus does not remain on the surface of the LSO material after reacting with the basic compounds in the LSO material. In summary, PAA can be included in the precursor mixture to help neutralize the pH of the precursor mixture and help prevent the formation of air bubbles within the precursor mixture for a duration of up to about 24 hours. In addition to neutralizing the pH of the precursor mixture, sPPP can also help prevent the formation of air bubbles in the precursor mixture for a duration greater than about 72 hours.

[0103] After forming the negative electrode 22 on the metal substrate (i.e., the negative electrode current collector 30), the negative electrode 22 can be assembled into the battery pack 20, and the negative electrode 22, the positive electrode 24, and the separator 26 can be infiltrated with the electrolyte 28. Then, the negative electrode current collector 30 and the positive electrode current collector 32 can be electrically coupled to the power source 34 such that lithium ions are released from the positive electrode 24 and incorporated into the negative electrode 22.

[0104] The foregoing description is merely exemplary and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure may be implemented in a variety of forms. Thus, while the disclosure includes specific examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be implemented in a different order (or concurrently) without altering the principles of the disclosure. Additionally, although the embodiments are described above as having certain features, any one or more of the features described with respect to any one embodiment of the disclosure may be implemented in and / or combined with the features of any other embodiment, even if not explicitly described in that combination. In other words, the described embodiments are not mutually exclusive, and the interchanging of one or more embodiments is still within the scope of the disclosure.

[0105] Various terms are used to describe spatial and functional relationships between components (e.g., between modules, circuit elements, semiconductor layers, etc.), including "connected", "joined", "coupled", "adjacent", "next to", "on top of", "on", "under", and "disposed". Unless explicitly described as "direct", when describing the relationship between a first element and a second element in the foregoing disclosure, the relationship can be a direct relationship in which no other intervening elements exist between the first element and the second element, or an indirect relationship in which one or more intervening elements exist between the first element and the second element (spatially or functionally). The phrase "at least one of A, B, and C" as used herein shall be construed to mean a logical (A or B or C) using non-exclusive logical OR and shall not be construed to mean "at least one of A, at least one of B, and at least one of C". As used herein, the term "and / or" includes any combination of one or more of the associated listed terms.

[0106] The terms used herein are for the purpose of describing exemplary embodiments only and are not intended to be limiting. Unless the context clearly dictates otherwise, the singular forms "a" and "the" as used herein are also intended to include the plural forms. The terms "comprising", "including", and "having" are inclusive and thus specify the presence of the stated features, elements, compositions, steps, integers, operations, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof. Although the open-ended terms "comprising", "including", and "having" should be understood as non-limiting terms for describing and claiming the various embodiments described herein, in some respects, these terms can alternatively be understood as more restrictive and limiting terms, such as "consisting of" or "consisting essentially of". Thus, for any given embodiment that lists a composition, material, component, element, ingredient, feature, integer, operation, and / or method step, the present disclosure also expressly includes embodiments consisting of or consisting essentially of these listed compositions, materials, components, elements, ingredients, features, integers, operations, and / or method steps. In the case of "consisting of", the alternative embodiment does not include any additional compositions, materials, components, elements, ingredients, features, integers, operations, and / or method steps, and in the case of "consisting essentially of", such an embodiment does not include any additional compositions, materials, components, elements, ingredients, features, integers, operations, and / or method steps that materially affect the basic and novel features, but may include any compositions, materials, components, elements, ingredients, features, integers, operations, and / or method steps that do not materially affect the basic and novel features.

[0107] Although terms such as first, second, third, etc. may be used herein to describe various steps, elements, components, regions, layers, and / or sections, these steps, elements, components, regions, layers, and / or sections should not be limited by these terms unless otherwise specified. These terms are only used to distinguish one step, element, component, region, layer, or section from another. Unless the context clearly indicates, terms such as "first" and "second" and other ordinal terms do not imply order or sequence when used herein. Thus, the first step, element, component, region, layer, or section discussed below may be referred to as the second step, element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0108] Throughout this disclosure, numerical values represent approximate measurements or range limits and include minor deviations from the given values and embodiments that generally have the recited values as well as embodiments that exactly have the recited values. Except for the examples provided at the end of the detailed description, all numerical values of parameters (such as amounts or conditions) in this specification should be understood to be modified in all instances by the term "about", whether or not the term "about" actually appears before the numerical value. The numerical values of parameters in the appended claims should be understood to be modified by the term "about" only when the term "about" appears before that numerical value. "About" means that a given numerical value allows for a certain degree of imprecision (close to the precision of the value; generally or reasonably close to the value; almost). If the imprecision provided by "about" is not understood in this ordinary sense in the art, "about" as used herein means at least the variation that may be caused by the ordinary methods of measuring and using such parameters. For example, "about" may include variations of less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5%, and in some aspects, optionally less than or equal to 0.1%. Additionally, the disclosure of a range includes the disclosure of all values within the entire range and further sub-ranges within the range, including the endpoints and sub-ranges given for those ranges.

[0109] Unless otherwise specified, the terms "composition" and "material" as used herein may be used interchangeably to generally refer to a substance that contains at least a preferred chemical composition, element, or compound but may also contain additional elements, compounds, or substances, including trace impurities. A "composition" or "material" "based on X" generally refers to a composition or material in which "X" is the single largest component of the composition or material on a weight percentage (%) basis. This can include compositions or materials having greater than 50% by weight of X, and can also include compositions or materials having less than 50% by weight of X, as long as X is the single largest component of the composition or material based on its total weight. When a composition or material is referred to as "substantially free of" a substance, the composition or material may contain less than 5%, optionally less than 3%, optionally less than 1%, or optionally less than 0.1% by weight of that substance.

[0110] As used herein, the term "metal" can refer to a pure elemental metal or an alloy of an elemental metal and one or more other metal or non-metal elements (referred to as "alloying" elements).

Claims

1. A method of manufacturing a negative electrode for a battery pack for cycling lithium ions, the method comprising: A precursor mixture is deposited on a substrate to form a precursor layer, the precursor mixture comprising: An electroactive negative electrode material comprising a lithiated subsilicon oxide (LSO) material and optionally graphite, wherein the LSO material includes a basic compound, Polymer binders, a functional polymer comprising an acidic functional group formulated to react with a basic compound in the LSO material to neutralize the pH of the precursor mixture, Aqueous solvents, and Optionally, a carbon-based electrochemically inactive conductive material; and The aqueous solvent is removed from the precursor layer to form the negative electrode on the substrate.

2. The method of claim 1, wherein the functional polymer comprises a poly(carboxylic acid), and wherein the acidic functional groups comprise carboxyl functional groups (-C(=O)OH).

3. The method of claim 2, wherein the functional polymer comprises poly(acrylic acid).

4. The method of claim 1, wherein the functional polymer comprises poly(sulfonic acid), and wherein the acidic functional group comprises a sulfonic functional group (-S(=O)2-OH).

5. The method of claim 4, wherein the functional polymer comprises sulfonated poly(phenylene) (sPP), sulfophenylated poly(phenylene) (sPPP), or a combination thereof.

6. The method of claim 1 , wherein the functional polymer is configured to react with lithium ions in the precursor mixture to form a lithium salt of the functional polymer, wherein the lithium salt of the functional polymer is insoluble in the aqueous solvent, and wherein the lithium salt of the functional polymer is configured to be deposited on the surface of the LSO material to form a physical barrier that prevents a chemical reaction between the LSO material and the aqueous solvent.

7. The method of claim 1, wherein the functional polymer has a molecular weight greater than or equal to about 10,000 g / mole and less than or equal to about 400,000 g / mole, wherein the LSO material has a nanoporous structure including open nanopores, and wherein the size of the functional polymer is such that the functional polymer can penetrate the open nanopores of the LSO material.

8. The method of claim 1, wherein the polymer binder comprises styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (Na-CMC).

9. The method of claim 1, wherein the alkaline compound comprises lithium hydroxide (LiOH), lithium carbonate (LiCO3), or a combination thereof.

10. The method according to claim 1, further comprising: preparing the precursor mixture by introducing the LSO material into a solution comprising the polymer binder, the functional polymer and the aqueous solvent, or The precursor mixture is prepared by preparing a first mixture comprising the LSO material and the functional polymer, preparing a second mixture comprising the polymer binder and the aqueous solvent, and then introducing the first mixture into the second mixture.

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