Method of manufacturing lithium-containing silicon oxide negative electrode comprising nitrate additive and battery comprising negative electrode

Abstract

The present invention provides a circulating lithium ion battery comprising a negative electrode comprising an electroactive negative electrode material, a polymeric binder, and a nitrate additive. A negative electrode is fabricated by depositing a precursor mixture on a substrate to form a precursor layer. The precursor mixture comprises an electroactive negative electrode material, a polymeric binder, a nitrate additive, and an aqueous solvent. The electroactive negative electrode material includes silicon, silicon oxide, lithiated silicon hypoxides, graphite, or a combination thereof. The aqueous solvent is removed from the precursor layer to form a negative electrode on the substrate.

Description

BACKGROUND OF THE DISCLOSURE

[0001] The present disclosure relates to methods of fabricating electrodes for a battery pack that cycles lithium ions, and more particularly to methods of fabricating a negative electrode that includes a silicon oxide-based electroactive material. TECHNICAL FIELD

[0002] The information provided in this section is intended to generally introduce the background of the present disclosure. To the extent that the operations currently attributed to the inventors are 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 to be taken as being admitted, either expressly or implicitly, as prior art against the present disclosure.

[0003] The present disclosure relates to methods of fabricating electrodes for a battery pack that cycles lithium ions, and more particularly to methods of fabricating a negative electrode that includes a silicon oxide-based electroactive material.

[0004] Battery packs that cycle lithium ions typically include a positive electrode, a negative electrode spaced apart from the positive electrode, and an ion-conductive electrolyte that provides a medium for the conduction of lithium ions 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 an ideal electroactive material for a negative electrode due to its high theoretical specific capacity.

[0005] Composite electrodes can be fabricated by depositing a slurry that includes an electroactive material, a conductive material, and a polymeric binder in a solvent as 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 DISCLOSURE

[0006] 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, a polymeric binder, a nitrate additive, and an aqueous solvent. The electroactive negative electrode material includes silicon, silicon oxide, lithiated silicon suboxide, graphite, or a combination thereof. The aqueous solvent is removed from the precursor layer to form a negative electrode on the substrate.

[0007] The nitrate additive can include lithium nitrate (LiNO 3 ), sodium nitrate (NaNO 3 ), potassium nitrate (KNO 3 ), copper nitrate (Cu(NO3 ) 2 ) or a combination thereof.

[0008] The nitrate additive may account for greater than or equal to about 0.01 wt% and less than or equal to about 2 wt% of the negative electrode.

[0009] In various embodiments, the precursor mixture can be prepared by preparing an adhesive solution comprising a polymer binder and at least a portion of an aqueous solvent, and then introducing the electroactive negative electrode material and the nitrate additive into the adhesive solution to form the precursor mixture. The method may further include introducing a conductive material into the adhesive solution before introducing the electroactive negative electrode material and the nitrate additive into the adhesive solution.

[0010] In various embodiments, the precursor mixture can be prepared by preparing a first solution comprising a polymer binder, a nitrate additive, and at least a portion of an aqueous solvent, and then introducing the electroactive negative electrode material into the first solution to form the precursor mixture. The method may further include introducing a conductive material into the first solution before introducing the electroactive negative electrode material into the first solution.

[0011] In various embodiments, the precursor mixture can be prepared by preparing an adhesive solution comprising a polymer binder and an aqueous solvent, preparing a nitrate solution comprising a nitrate additive and an aqueous solvent, and mixing the adhesive solution, the nitrate solution, and the electroactive negative electrode material together to form the precursor mixture. The method may further include introducing a conductive material into the adhesive solution before mixing the adhesive solution with the nitrate solution and the electroactive negative electrode material.

[0012] The polymer binder may include styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), sodium alginate, or a combination thereof.

[0013] The polymer binder may account for greater than or equal to about 2 wt% and less than or equal to about 10 wt% of the negative electrode.

[0014] The precursor mixture may further comprise a conductive material. The conductive material may account for greater than or equal to about 2 wt% and less than or equal to about 10 wt% of the negative electrode.

[0015] The electroactive negative electrode material may account for greater than or equal to about 80 wt% and less than or equal to about 97 wt% of the negative electrode.

[0016] The electroactive negative electrode material may further comprise graphite.

[0017] In a method of manufacturing a rechargeable lithium-ion battery pack according to one or more embodiments of the present disclosure, a precursor mixture is deposited on a copper current collector to form a precursor layer. The precursor mixture includes an electroactive negative electrode material, a polymer binder, a nitrate additive, and an aqueous solvent. The electroactive negative electrode material includes silicon, silicon oxide, lithiated silicon suboxide, graphite, or a combination thereof. The nitrate additive includes lithium nitrate (LiNO 3 ), sodium nitrate (NaNO 3 ), potassium nitrate (KNO 3 ), copper nitrate (Cu(NO 3 )) 2 ) or a combination thereof. The aqueous solvent is removed from the precursor layer to form a negative electrode on the copper current collector. The negative electrode and the copper current collector are assembled into a stack that 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.

[0018] The nitrate additive may include LiNO 3 . In this case, LiNO 3 may account for greater than or equal to about 0.05 wt% and less than or equal to about 0.4 wt% of the negative electrode.

[0019] The polymer binder may include styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), sodium alginate, or a combination thereof.

[0020] The method may further include impregnating the negative electrode, the positive electrode, and the separator with an electrolyte that includes a lithium salt in a polar aprotic organic solvent. The electrolyte may be substantially free of nitrate compounds.

[0021] The method may further include charging the battery pack by electrically coupling the negative electrode current collector and the positive electrode current collector to a power source such that lithium ions are released from the positive electrode and incorporated into the negative electrode. During charging of the battery pack, the nitrate additive may react with the electroactive negative electrode material to form an electrically insulating and ionically conductive solid interface layer on the surface of the electroactive negative electrode material.

[0022] The polar aprotic organic solvent may include a mixture of cyclic carbonates and linear carbonates.

[0023] A battery pack for cycling lithium ions according to one or more embodiments of the present disclosure includes a negative electrode, a positive electrode spaced apart from the negative electrode, a separator sandwiched between the negative electrode and the positive electrode, and an electrolyte permeating the negative electrode, the positive electrode, and the separator. The negative electrode includes electroactive negative electrode material particles mixed with a polymer binder, nitrate additive particles, and a conductive carbon-based material. The electroactive negative electrode material particles include silicon, silicon oxide, lithiated silicon suboxide, graphite, or a combination thereof. The nitrate additive particles include lithium nitrate (LiNO 3 )、sodium nitrate (NaNO 3 )、potassium nitrate (KNO 3 )、copper nitrate (Cu(NO 3 ) 2 ) or a combination thereof. The nitrate additive particles account for greater than or equal to about 0.05 wt% and less than or equal to about 0.4 wt% of the negative electrode. The polymer binder includes styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), sodium alginate, or a combination thereof. The positive electrode includes an electroactive positive electrode material. The electrolyte includes a lithium salt in a polar aprotic organic solvent. The electrolyte and the separator are substantially free of nitrate compounds.

[0024] The electrolyte may further include an electrolyte additive selected from lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB), and lithium fluoromalonate( difluoro)borate (LiFMDFB). The electrolyte additive may account for greater than or equal to about 0.5 wt% and less than or equal to about 2 wt% of the electrolyte.

[0025] The present invention provides the following solutions:

[0026] Solution 1. A method of manufacturing a negative electrode for a battery pack for cycling 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, a polymer binder, a nitrate additive, and an aqueous solvent, the electroactive negative electrode material comprising silicon, silicon oxide, lithiated silicon suboxide, graphite, or a combination thereof; and

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

[0029] Solution 2. The method according to Solution 1, wherein the nitrate additive includes lithium nitrate (LiNO 3 )、sodium nitrate (NaNO 3 )、potassium nitrate (KNO 3 )、copper nitrate (Cu(NO 3 ) 2 ) or a combination thereof.

[0030] Embodiment 3. The method according to Embodiment 1, wherein the nitrate additive accounts for greater than or equal to about 0.01% by weight and less than or equal to about 2% by weight of the negative electrode.

[0031] Embodiment 4. The method according to Embodiment 1, further comprising:

[0032] preparing the precursor mixture by:

[0033] preparing an adhesive solution comprising a polymer binder and at least a portion of an aqueous solvent; and then

[0034] introducing the electroactive negative electrode material and the nitrate additive into the adhesive solution to form the precursor mixture.

[0035] Embodiment 5. The method according to Embodiment 4, further comprising:

[0036] introducing a conductive material into the adhesive solution before introducing the electroactive negative electrode material and the nitrate additive into the adhesive solution.

[0037] Embodiment 6. The method according to Embodiment 1, further comprising:

[0038] preparing the precursor mixture by:

[0039] preparing a first solution comprising a polymer binder, a nitrate additive, and at least a portion of an aqueous solvent; and

[0040] introducing the electroactive negative electrode material into the first solution to form a precursor mixture.

[0041] Embodiment 7. The method according to Embodiment 6, wherein preparing the precursor mixture further comprises:

[0042] introducing a conductive material into the first solution before introducing the electroactive negative electrode material into the first solution.

[0043] Embodiment 8. The method according to Embodiment 1, further comprising:

[0044] preparing the precursor mixture by:

[0045] preparing an adhesive solution comprising a polymer binder and an aqueous solvent;

[0046] preparing a nitrate solution comprising a nitrate additive and an aqueous solvent; and

[0047] mixing the adhesive solution, the nitrate solution, and the electroactive negative electrode material together to form the precursor mixture.

[0048] Scheme 9. The method according to Scheme 8, wherein preparing the precursor mixture further comprises:

[0049] Before mixing the binder solution with the nitrate solution and the electroactive negative electrode material, introducing a conductive material into the binder solution.

[0050] Scheme 10. The method according to Scheme 1, wherein the polymeric binder comprises styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), sodium alginate, or a combination thereof, and wherein the polymeric binder accounts for greater than or equal to about 2 wt% and less than or equal to about 10 wt% of the negative electrode.

[0051] Scheme 11. The method according to Scheme 1, wherein the precursor mixture further comprises a conductive material, and wherein the conductive material accounts for greater than or equal to about 2 wt% and less than or equal to about 10 wt% of the negative electrode.

[0052] Scheme 12. The method according to Scheme 1, wherein the electroactive negative electrode material accounts for greater than or equal to about 80 wt% and less than or equal to about 97 wt% of the negative electrode.

[0053] Scheme 13. The method according to Scheme 1, wherein the electroactive negative electrode material further comprises graphite.

[0054] Scheme 14. A method of manufacturing a battery pack for recycling lithium ions, the method comprising:

[0055] Depositing a precursor mixture on a copper current collector to form a precursor layer, the precursor mixture comprising an electroactive negative electrode material, a polymeric binder, a nitrate additive, and an aqueous solvent, the electroactive negative electrode material comprising silicon, silicon oxide, lithium silicate low oxide, graphite, or a combination thereof, the nitrate additive comprising lithium nitrate (LiNO 3 )), sodium nitrate (NaNO 3 ), potassium nitrate (KNO 3 ), copper nitrate (Cu(NO 3 )) 2 ) or a combination thereof;

[0056] Removing the aqueous solvent from the precursor layer to form a negative electrode on the copper current collector; and

[0057] Assembling the negative electrode and the copper current collector into a stack, the stack comprising a positive electrode disposed on a positive electrode current collector and a separator sandwiched between opposite facing surfaces of the negative electrode and the positive electrode, the positive electrode comprising lithium ions.

[0058] Scheme 15. The method according to Scheme 14, wherein the nitrate additive comprises LiNO3 and wherein LiNO 3 is greater than or equal to about 0.05 wt% and less than or equal to about 0.4 wt% of the negative electrode.

[0059] Aspect 16. The method according to aspect 14, wherein the polymeric binder comprises styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), sodium alginate, or a combination thereof.

[0060] Aspect 17. The method according to aspect 14, further comprising:

[0061] impregnating the negative electrode, the positive electrode, and the separator with an electrolyte comprising a lithium salt in a polar aprotic organic solvent, the electrolyte being substantially free of nitrate compounds; and

[0062] charging the battery pack by electrically coupling the negative electrode current collector and the positive electrode current collector to a power source such that lithium ions are released from the positive electrode and incorporated into the negative electrode,

[0063] wherein during charging of the battery pack, the nitrate additive reacts with the electroactive negative electrode material to form an electrically insulating and ionically conductive solid interface layer on the surface of the electroactive negative electrode material.

[0064] Aspect 18. The method according to aspect 14, wherein the polar aprotic organic solvent comprises a mixture of a cyclic carbonate and a linear carbonate.

[0065] Aspect 19. A battery pack for cycling lithium ions, the battery pack comprising:

[0066] a negative electrode comprising electroactive negative electrode material particles, nitrate additive particles, and a conductive carbon-based material mixed with a polymeric binder, the electroactive negative electrode material particles comprising silicon, silicon oxide, lithiated silicon suboxide, graphite, or a combination thereof, the nitrate additive particles comprising lithium nitrate (LiNO 3 ), sodium nitrate (NaNO 3 ), potassium nitrate (KNO 3 ), copper nitrate (Cu(NO 3 )) 2 ) or a combination thereof, and being greater than or equal to about 0.05 wt% and less than or equal to about 0.4 wt% of the negative electrode, the polymeric binder comprising styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), sodium alginate, or a combination thereof;

[0067] a positive electrode spaced apart from the negative electrode and comprising an electroactive positive electrode material;

[0068] A separator sandwiched between the negative electrode and the positive electrode; and

[0069] An electrolyte permeating the negative electrode, the positive electrode, and the separator, the electrolyte comprising a lithium salt in a polar aprotic organic solvent,

[0070] wherein the electrolyte and the separator are substantially free of nitrate compounds.

[0071] Item 20. The battery pack according to Item 19, wherein the electrolyte further comprises an electrolyte additive selected from lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB), and lithium fluoromalonate(difluoro)borate (LiFMDFB), and wherein the electrolyte additive accounts for greater than or equal to about 0.5 wt% and less than or equal to about 2 wt% of the electrolyte.

[0072] From the detailed description, the claims, and the drawings, further applicable fields of the present disclosure will become apparent. The detailed description and specific examples are only intended to illustrate and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] The present disclosure will be more fully understood through the detailed description and the drawings, wherein:

[0074] Figure 1 is a schematic perspective view of a motor vehicle powered by a battery pack including a plurality of battery pack modules.

[0075] Figure 2 is Figure 1 a schematic cross-sectional view of a part of one of the battery pack modules, the battery pack module including a plurality of electrochemical cells or battery packs that cycle lithium ions.

[0076] Figure 3 is a 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 permeating the positive electrode, the negative electrode, and the porous separator.

[0077] Figure 4 , Figure 5 and Figure 6 are flowcharts depicting steps in first, second, and third methods of manufacturing Figure 3 the negative electrode of.

[0078] In the drawings, reference numerals may be reused to identify similar and / or identical elements. DETAILED DESCRIPTION

[0079] The currently disclosed method can be used to fabricate a negative electrode for a battery pack for cycling lithium ions. The negative electrode includes an electroactive material comprising lithiated silicon low oxide (LSO), a polymeric binder, and a nitrate additive. During the fabrication of the negative electrode, a precursor mixture comprising the electroactive material, the polymeric binder, and the nitrate additive in an aqueous solvent 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. The nitrate additive has high solubility in the aqueous solvent, which enables the nitrate additive to be uniformly and tightly mixed with the electroactive material in the precursor mixture and the resulting negative electrode. During the initial charge and cycling of the battery pack, the nitrate additive is formulated to react with the electroactive material in the negative electrode to form a solid interface layer on the electroactive material, thereby preventing or suppressing an undesired side reaction between the electroactive material and the electrolyte..

[0080] Figure 1 Depicted is a motor vehicle 2 powered by an electric motor 4 that draws 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 desired capacity and power requirements of the electric motor 4. The vehicle 2 can be an all-electric vehicle and can be powered solely by the electric motor 4, or the vehicle 2 can be a hybrid electric vehicle and can be powered by the electric motor 4 and an internal combustion engine (not shown).

[0081] As Figure 2 shown, each battery pack module 8 includes one or more electrochemical cells or battery packs 10 for cycling lithium ions. In practice, the battery packs 10 in the battery pack module 8 are typically assembled as a stack of layers including 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 impregnated with an electrolyte that provides a medium for the conduction of lithium ions between the negative electrode layer 12 and the positive electrode layer 14, or the separator layer 16 itself can act 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, and 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, the 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, respectively, on both sides thereof. In this 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.

[0082] Figure 3Depicts an electrochemical cell or battery pack 20 with a cyclic lithium ion. The battery pack 20 can generate an electric 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 Figure 2 the battery pack 10 shown in, in all 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 provide power to fixed and / or portable electronic devices, components, and devices used in a variety of other industries and applications (as non-limiting examples, including industrial, residential, and commercial buildings, consumer goods, industrial equipment and machinery, agricultural or farming equipment, and heavy machinery).

[0083] The battery pack 20 includes a negative electrode 22, a positive electrode 24, a separator 26, and an electrolyte 28, and the electrolyte 28 provides a medium for the conduction of lithium ions 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 and the positive electrode 24 is disposed on the main surface of a positive electrode current collector 32. The negative electrode 22 includes a solid interface layer 38 disposed on its surface 40. In fact, 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 such that when the battery pack 20 is at least partially charged, an electrochemical potential difference is established between the negative electrode 22 and the positive electrode 24. During discharge of the battery pack 20, the electrochemical potential difference established between the negative electrode 22 and the positive electrode 24 drives spontaneous reduction and oxidation (redox) reactions within the battery pack 20 and the release of lithium ions and electrons at the negative electrode 22. The released lithium ions move from the negative electrode 22 through the separator 26 and the electrolyte 28 to the positive electrode 24, while the electrons move from the negative electrode 22 to the positive electrode 24 through the external circuit 36, thereby generating 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. The repeated discharge and charge of the battery pack 20 can be referred to herein as "cycling", where one complete discharge event following one complete charge event is considered one complete cycle.

[0084] The negative electrode 22 is configured 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 layer of a material disposed on a major surface of the negative electrode current collector 30. The negative electrode 22 includes an electrochemically active (electroactive) material, a polymeric binder, a nitrate additive, and an optional conductive material. The electroactive material of the negative electrode 22 may be referred to herein as the "electroactive negative electrode material". In various embodiments, the electroactive material of the negative electrode 22 may be particulate material, and the particles of the electroactive material may be mixed with the polymeric binder, the nitrate additive, and the optional conductive material in the negative electrode 22. 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.

[0085] The electroactive material of the negative electrode 22 is configured 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 comprise greater than or equal to about 80 weight percent, or optionally greater than or equal to about 90 weight percent, and less than or equal to about 97 weight percent, or optionally less than or equal to about 95 weight percent of the negative electrode 22.

[0086] The electroactive material of the negative electrode 22 includes a lithiated silicon low oxide (LSO) material. Before the initial charging of the battery pack 20, the LSO material may have the following formula (1):

[0087] Li x SiO y ,(1)

[0088] where 0 < x ≤ 2 and 0 < y ≤ 2.

[0089] In fact, the LSO material may comprise a variety of different Si, Li, and / or O-containing compounds, where the overall composition of the LSO material is represented by formula (1). For example, in various embodiments, the LSO material may include pure elemental silicon (Si), lithium silicide (Li x Si, such as LiSi), silicon oxide (SiO x , such as SiO and / or SiO 2 ), lithium silicate (Li x Si y O z , such as Li 2 Si 2 O 5 , Li 2 SiO 3 , Li 6 Si 2 O 7 and / or Li4 SiO 4 ) or a combination thereof.

[0090] As an electroactive material, silicon suboxide (SiO x , where 0 < x ≤ 2) can promote the storage of lithium in the negative electrode 22 during the charging process of the battery pack 20 by forming an alloy (lithiation) with lithium, and during the discharging process of the battery pack 20, lithium ions can be released therefrom by dealloying (delithiation) from SiO x . However, during the initial charging process of the battery pack 20, an undesired irreversible side reaction often occurs between lithium ions and SiO x , resulting in the consumption of active lithium, irreversible capacity loss, and low initial Coulombic efficiency. It has been found that pre-lithiation of SiO x before incorporation into the negative electrode 22 to form an LSO material can reduce the occurrence of undesired irreversible side reactions between lithium and SiO x during the initial cycling of the battery pack 20, thereby improving the reversible capacity and cycling stability of the battery pack 20.

[0091] In various embodiments, the LSO material can have an open nanoporous structure having open pores (nanopores) with a diameter greater than or equal to about 1 nanometer (nm) and less than or equal to about 100 nm. The LSO material can account for greater than or equal to about 10 wt%, optionally greater than or equal to about 20 wt%, optionally greater than or equal to about 30 wt%, optionally greater than or equal to about 40 wt%, optionally greater than or equal to about 50 wt%, optionally greater than or equal to about 60 wt%, optionally greater than or equal to about 70 wt%, optionally greater than or equal to about 80 wt%, optionally greater than or equal to about 90 wt%, and less than or equal to about 100 wt% of the electroactive material of the negative electrode 22.

[0092] In addition to the LSO material, the negative electrode 22 can further include one or more other electroactive materials. Examples of other electroactive negative electrode materials include lithium, lithium-based materials (e.g., alloys of lithium with 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 with lithium, tin, iron, aluminum, and / or cobalt), silicon oxides, tin oxides, aluminum, indium, zinc, germanium, titanium oxides, lithium titanate, and combinations thereof. In various embodiments, the electroactive material of the negative electrode 22 can include a composite material of the LSO material and graphite. For example, in various embodiments, the electroactive material of the negative electrode 22 can include the LSO material and graphite.

[0093] The polymeric binder is electrochemically inert 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. Examples of polymeric binders include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene propylene diene monomer (EPDM), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), nitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), styrene-ethylene-butylene-styrene copolymer (SEBS), polyacrylate, alginate, polyacrylic acid (PAA), and combinations thereof. In various embodiments, the polymeric binder can include styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (Na-CMC), polyacrylic acid (PAA), sodium polyacrylate (Na-PAA), lithium polyacrylate (Li-PAA), sodium alginate, or combinations thereof. The polymeric binder can account for greater than or equal to about 2 wt% and less than or equal to about 10 wt% of the negative electrode 22.

[0094] The conductive material is optional and can be included in the negative electrode 22 to provide good electrical conductivity to the negative electrode 22. Examples of conductive materials include carbon-based materials, metals (such as nickel), and / or conductive polymers. Examples of conductive carbon-based 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 in the negative electrode 22, the conductive material can account for greater than or equal to about 0.5 wt% and less than or equal to about 10 wt% of the negative electrode 22.

[0095] The nitrate additive is formulated to assist in forming the solid interface layer 38 on the surface 40 of the negative electrode 22. The nitrate additive includes metal nitrates. For example, the nitrate additive can include lithium nitrate (LiNO 3 ), sodium nitrate (NaNO 3 ), potassium nitrate (KNO 3 ), copper nitrate (Cu(NO 3 )) 2 ), or combinations thereof.

[0096] For example, due to the chemical reaction between the nitrate additive and the electroactive material of the negative electrode 22, the solid interface layer 38 can be inherently formed in situ on the surface 40 of the negative electrode 22 after the assembly of the battery pack 20 and / or during the initial charging and / or cycling of the battery pack 20. In various embodiments, due to the electrochemical reduction of the nitrate additive on the surface 40 of the electroactive material of the negative electrode 22, the solid interface layer 38 can be inherently formed in situ on the surface 40 of the negative electrode 22 during the charging and / or cycling of the battery pack 20. In such cases, the solid interface layer 38 can comprise the electrochemical decomposition products of the nitrate additive. In Figure 3 , the solid interface layer 38 is depicted as being disposed along the interface between the negative electrode 22 and the separator 26. However, in reality, the solid interface layer 38 extends throughout the negative electrode 22 between the negative electrode current collector 30 and the separator 26. For example, the solid interface layer 38 can be disposed on the surface of the electroactive material particles in the negative electrode 22. In various embodiments, the solid interface layer 38 can extend around and substantially over the entire surface of each electroactive material particle in the negative electrode 22 such that each electroactive material particle is encapsulated by the solid interface layer 38.

[0097] The solid interface layer 38 is electrically insulating and ionically conductive and is configured to help prevent an undesired chemical reaction between the electrolyte 28 and the electroactive material of the negative electrode 22 during the cycling of the battery pack 20. For example, the solid interface layer 38 can help prevent a chemical reaction between the components of the electrolyte 28 and the electroactive material of the negative electrode 22 during the charging and / or discharging of the battery pack 20. The formation of the solid interface layer 38 can help prevent an undesired chemical reaction between the electrolyte 28 and the electroactive material of the negative electrode 22 without hindering the flow of lithium ions between the electrolyte 28 and the negative electrode 22.

[0098] The nitrate additive can account for greater than or equal to about 0.01 wt% of the negative electrode 22, or optionally greater than or equal to about 0.05 wt%, and less than or equal to about 2 wt%, or optionally less than or equal to about 0.4 wt%. In various embodiments, the nitrate additive can comprise LiNO 3 and can account for greater than or equal to about 0.05 wt% and less than or equal to about 0.4 wt% of the negative electrode 22.

[0099] When the nitrate additive is included in the negative electrode 22 in an amount greater than or equal to about 0.01% and less than or equal to about 2% of the negative electrode 22, the nitrate additive can effectively assist in the formation of the solid electrolyte interface layer 38 on the surface 40 of the negative electrode 22, and thereby improve the capacity retention and cycling stability of the battery pack 20 as compared to a negative electrode formed without the addition of the nitrate additive. Additionally, including the nitrate additive in the negative electrode 22 before assembling the battery pack 20 (i.e., before introducing the electrolyte 28 into the battery pack 20) can contribute to improving the long-term stability of the solid electrolyte interface layer 38, thereby avoiding an increase in the thickness of the solid electrolyte interface layer 38 and further increase in the internal resistance of the battery pack 20 after more than about 20 cycles. In various embodiments, it may be desirable for the nitrate additive to be less than about 0.5 wt% of the negative electrode 22 to help promote the formation of a thin and effective solid electrolyte interface layer 38 on the surface 40 of the negative electrode 22 without unnecessarily increasing the internal resistance of the battery pack 20.

[0100] The positive electrode 24 is configured to store and release lithium ions during discharge and charge of the battery pack 20. The positive electrode 24 may be in the form of a continuous porous layer disposed on the major surface of the positive electrode current collector 32. The positive electrode 24 includes an electroactive material (electroactive positive electrode material), a polymeric binder, and optionally a conductive material.

[0101] The electroactive material of the positive electrode 24 can store and release lithium ions by undergoing a reversible redox reaction with lithium at a higher electrochemical potential than 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. The electroactive material of the positive electrode 24 can include a material capable of 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 matrix material capable of reversible insertion or intercalation of lithium ions, the electroactive material of the positive electrode 24 may 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 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 transition metal sulfate fluoride represented by the formula LiMeSO 4 F or LiMePO 4One or two of F represent tavorite, or a combination thereof, 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 Mn 1-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 where the electroactive material of the positive electrode 24 includes a conversion material, 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, fluorides, sulfur fluorides, sulfur fluoroxides, or lithium and / or its metal compounds (e.g., compounds of iron, manganese, nickel, copper, and / or cobalt).

[0102] The polymeric binder is electrochemically inert and can be included in the positive electrode 24 to provide structural integrity to the positive electrode 24 and / or 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), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), nitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), styrene-ethylene-butylene-styrene copolymer (SEBS), polyacrylate, alginate, polyacrylic acid, and combinations thereof.

[0103] The optional conductive material is electrochemically inert and can be included in the positive electrode 24 to provide sufficient conductivity to the positive electrode 24 to support the infiltration of electrons therein. Examples of conductive materials for the positive electrode 24 include carbon-based materials, metals (such as nickel), and / or conductive polymers. Examples of conductive carbon-based 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.

[0104] The separator 26 is configured to physically separate and electrically isolate the negative electrode 22 and the positive electrode 24 from each other while allowing lithium ions to pass therethrough. The separator 26 has an open microporous structure and can comprise organic and / or inorganic materials. For example, the separator 26 can comprise a polymer, such as a polyolefin. In various embodiments, the separator 26 can include polyethylene (PE), polypropylene (PP), polyamide (PA), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and / or poly(vinyl chloride) (PVC).

[0105] The electrolyte 28 is ion-conductive and is formulated to provide a medium for the conduction of lithium ions between the negative electrode 22 and the positive electrode 24. The electrolyte 28 comprises an organic solvent, a lithium salt in the organic solvent, and optionally an electrolyte additive.

[0106] 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), and ethyl methyl carbonate (EMC)); aliphatic carboxylic acid esters (e.g., methyl formate, methyl acetate, and 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. In various embodiments, the organic solvent may include a mixture of a cyclic carbonate (e.g., EC) and a linear carbonate (e.g., DMC).

[0107] 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(trifluoromethanesulfonyl)imide (LiN(CF 3 SO 2 )) 2 ), lithium bis(fluorosulfonyl)imide (LiN(FSO 2 )) 2 (LiSFI), lithium tetraphenylborate (LiB(C 6 H 5 )) 4 ), lithium bis(oxalato)borate (LiB(C 2 O 4 )) 2)(LiBOB), lithium difluoro(oxalato)borate (LiBF 2 (C 2 O 4 ))(LiDFOB), and combinations thereof.

[0108] Optional electrolyte additives are configured to assist in forming a solid electrolyte interphase layer 38 on the surface 40 of the negative electrode 22. Examples of such electrolyte additives include fluoroethylene carbonate (FEC), vinylene carbonate (VC), lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB), lithium fluoromalonate(difluoro)borate (LiFMDFB), and combinations thereof. When present, the electrolyte additives can be present in the electrolyte 28 in an amount greater than or equal to about 0.5 wt% and less than or equal to about 2 wt%.

[0109] The electrolyte 28 and the separator 26 can be substantially free of nitrate compounds. Specifically, the electrolyte 28 and the separator 26 can be substantially free of LiNO 3 , NaNO 3 , KNO 3 and / or copper nitrate (Cu(NO 3 )) 2 ).

[0110] 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 various 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.

[0111] Method

[0112] The negative electrode 22 can be manufactured by depositing a precursor mixture on a metal substrate to form a precursor layer. The precursor mixture includes an electroactive negative electrode material (i.e., the LSO material and optionally one or more other electroactive materials), a polymer binder, a nitrate additive, and optionally a conductive material in an aqueous solvent (such as water). After forming the precursor layer on the metal substrate, the aqueous solvent is removed from the precursor layer (e.g., by evaporation) to form the negative electrode 22 on the metal substrate. In various embodiments, the metal substrate can be made of substantially the same material as the negative electrode current collector 30. For example, the metal substrate can include a copper current collector.

[0113] Introducing the nitrate additive into the negative electrode 22 during the manufacture of the negative electrode 22 and prior to assembly of the battery 20, rather than introducing the nitrate additive into the negative electrode 22 (and the battery 20) with the electrolyte 28, provides several significant benefits. First, the nitrate additive has an exceptionally high solubility in solvents such as water compared to its solubility in organic solvents included in the electrolyte 28. Therefore, including the nitrate additive in the precursor mixture used to form the negative electrode 22 helps to more evenly distribute the nitrate additive throughout the negative electrode 22 and ensure more intimate contact between the electroactive negative electrode material and the nitrate additive, compared to introducing the nitrate additive into the battery 20 (and the negative electrode 22) with the electrolyte 28 during the assembly of the battery 20 (after the negative electrode 22 is formed).

[0114] Figure 4 、 Figure 5 and Figure 6 Depicted are first, second, and third methods 100, 200, 300, respectively, for preparing a precursor mixture 50 comprising an electroactive negative electrode material 52, a polymer binder 54, a nitrate additive 56, an aqueous solvent 58, an optional conductive material 60, and an optional additional binder 62. The electroactive negative electrode material 52, the polymer binder 54, the nitrate additive 56, and the optional conductive material 60 may comprise substantially the same materials as the electroactive negative electrode material, polymer binder, nitrate additive, and optional conductive material described above with respect to the negative electrode 22, and may be present in substantially the same proportions in the precursor mixture 50. The aqueous solvent 58 comprises water and the optional additional binder 62 may comprise styrene butadiene rubber (SBR). The first, second, and third methods 100, 200, 300 may be prepared at about ambient temperature (e.g., about 25 degrees Celsius (° C.)).

[0115] If Figure 4As shown, in the first method 100, in the first step 110, the polymeric binder 54 and at least a portion of the aqueous solvent 58 are mixed together at a low shear rate to form a binder solution 64. In an optional second step 120, in embodiments where the precursor mixture 50 includes the conductive material 60, the conductive material 60 is introduced into the polymeric binder 54 and the aqueous solvent 58 in the binder solution 64 and mixed with the polymeric binder 54 and the aqueous solvent 58 in the binder solution 64 at a low shear rate, and then mixed at a relatively high shear rate. In the third step 130, the electroactive negative electrode material 52 and the nitrate additive 56 are introduced into the polymeric binder 54, the aqueous solvent 58, and the optional conductive material 60 in the binder solution 64 and mixed with the polymeric binder 54, the aqueous solvent 58, and the optional conductive material 60 in the binder solution 64 at a low shear rate, and then mixed at a relatively high shear rate to form the precursor mixture 50. In an optional fourth step 140, in embodiments where the precursor mixture 50 includes the additional binder 62, the additional binder 62 is introduced into the composition including the polymeric binder 54, the aqueous solvent 58, the optional conductive material 60, the electroactive negative electrode material 52, and the nitrate additive 56 and mixed with the composition at a low shear rate to form the precursor mixture 50. In an optional fifth step 150, an additional amount of the aqueous solvent 58 may be introduced into the composition including the polymeric binder 54, the aqueous solvent 58, the optional conductive material 60, the electroactive negative electrode material 52, the nitrate additive 56, and the optional additional binder 62 and mixed with the composition at a low shear rate to form the precursor mixture 50.

[0116] As Figure 5As shown in, in the second method 200, in the first step 210, the polymer binder 54, the nitrate additive 56, and at least a portion of the aqueous solvent 58 are mixed together at a low shear rate to form a first solution 66. In an optional second step 220, in embodiments where the precursor mixture 50 includes the conductive material 60, the conductive material 60 is introduced into and mixed with the polymer binder 54, the nitrate additive 56, and the aqueous solvent 58 in the first solution 66 at a low shear rate and then at a relatively high shear rate. In the third step 230, the electroactive negative electrode material 52 is introduced into and mixed with the polymer binder 54, the nitrate additive 56, the aqueous solvent 58, and the optional conductive material 60 in the first solution 66 at a low shear rate and subsequently at a relatively high shear rate to form the precursor mixture 50. In an optional fourth step 240, in embodiments where the precursor mixture 50 includes the additional binder 62, the additional binder 62 is introduced into and mixed with the composition including the polymer binder 54, the nitrate additive 56, the aqueous solvent 58, the electroactive negative electrode material 52, and the optional conductive material 60 at a low shear rate to form the precursor mixture 50. In an optional fifth step 250, an additional amount of the aqueous solvent 58 can be introduced into and mixed with the composition including the polymer binder 54, the nitrate additive 56, the aqueous solvent 58, the electroactive negative electrode material 52, the optional conductive material 60, and the optional additional material at a low shear rate to form the precursor mixture 50.

[0117] As Figure 6As shown, in the third method 300, in a first step 310, the polymeric binder 54 and at least a portion of the aqueous solvent 58 are mixed together at a low shear rate to form a binder solution 64. In an optional second step 320, in embodiments where the precursor mixture 50 includes the conductive material 60, the conductive material 60 is introduced into the polymeric binder 54 and the aqueous solvent 58 in the binder solution 64 and mixed with the polymeric binder 54 and the aqueous solvent 58 in the binder solution 64 at a low shear rate, and then mixed at a relatively higher shear rate. In a third step 330, the nitrate additive 56 and at least a portion of the aqueous solvent 58 are mixed together at a low shear rate to form a nitrate solution 68. In a fourth step 340, the electroactive negative electrode material 52 and the nitrate solution 68 are introduced into the composition including the polymeric binder 54, the aqueous solvent 58, and optionally the conductive material 60 and mixed with it at a low shear rate, and then mixed at a relatively higher shear rate to form the precursor mixture 50. In an optional fifth step 350, in embodiments where the precursor mixture 50 includes the additional binder 62, the additional binder 62 is introduced into the composition including the polymeric binder 54, the nitrate additive 56, the aqueous solvent 58, the electroactive negative electrode material 52, and optionally the conductive material 60 and mixed with it at a low shear rate to form the precursor mixture 50. In an optional sixth step 360, an additional amount of the aqueous solvent 58 can be introduced into the composition including the polymeric binder 54, the nitrate additive 56, the aqueous solvent 58, the electroactive negative electrode material 52, optionally the conductive material 60, and optionally the additional binder 62 and mixed with it at a low shear rate to form the precursor mixture 50.

[0118] The foregoing description is exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can 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 after study of the drawings, the specification, and the appended claims. It should be understood that one or more steps within a method may be performed in a different order (or concurrently) without altering the principles of the disclosure. Further, 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 can be implemented in any other embodiment 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 permutations of one or more of the embodiments are still within the scope of the disclosure.

[0119] Various terms are used to describe the 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 above disclosure, the relationship can be a direct relationship where no other intermediate element exists between the first element and the second element, or an indirect relationship where one or more intermediate elements exist (spatially or functionally) between the first element and the second element. The phrase "at least one of A, B, and C" as used herein should be construed to mean a logical (A or B or C) using non-exclusive logical OR, and should not be construed to mean "at least one A, at least one B, and at least one C". The term "and / or" as used herein includes any combination of one or more of the associated listed items.

[0120] The terms used herein are for the purpose of describing particular exemplary embodiments only and are not intended to be limiting. Unless the context clearly dictates otherwise, as used herein, the singular forms "a", "an", and "the" may be intended to also include the plural forms. The terms "comprising", "including", "covering", 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 groups thereof. Although the open-ended term "including" should be understood as a non-limiting term for describing and claiming the various embodiments described herein, in some instances, the term may alternatively be understood as a more restrictive and limiting term, such as "consisting of" or "consisting essentially of". Thus, for any given embodiment reciting a composition, material, component, element, feature, integer, operation, and / or method step, the present disclosure also specifically includes embodiments consisting of or consisting essentially of such recited composition, material, component, element, feature, integer, operation, and / or method step. In the case of "consisting of", alternative embodiments exclude any additional compositions, materials, components, elements, features, integers, operations, and / or method steps, while in the case of "consisting essentially of", any additional compositions, materials, components, elements, features, integers, operations, and / or method steps that materially affect the basic and novel characteristics are excluded from such embodiments, but any compositions, materials, components, elements, features, integers, operations, and / or method steps that do not materially affect the basic and novel characteristics may be included in the various embodiments.

[0121] Any method steps, processes, and operations described herein should not be construed as necessarily requiring them to be performed in the particular order discussed or illustrated, unless explicitly determined as the order of performance. It is also understood that additional or alternative steps may be employed, unless otherwise stated. Although the terms 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 stated. These terms may be used only to distinguish one step, element, component, region, layer, or section from another. Unless the context clearly indicates, terms such as "first," "second," and other numerical terms used herein do not imply an order or sequence. 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.

[0122] Throughout this disclosure, numerical values represent approximate measurements or range bounds to encompass minor deviations from a given value and embodiments that generally have the recited value as well as embodiments that exactly have the recited value. Except in the working examples provided at the end of the detailed description, all numerical values of parameters (such as amounts or conditions) in this specification (including the appended claims) 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. "About" means that the recited numerical value allows for a certain degree of imprecision (being somewhat close to the exact value of that value; generally or reasonably approximating that value; nearly). If the imprecision provided by "about" is not otherwise understood in the art in this ordinary sense, then "about" as used herein means at least the deviation that may be caused by the ordinary methods of measuring and using such parameters. For example, "about" may include deviations 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, including the disclosure of the endpoints and sub-ranges given for that range.

[0123] As used herein, the terms "composition" and "material" are used interchangeably and generally refer to a substance that includes at least a preferred chemical component, element, or compound, but may also include additional elements, compounds, or substances, including trace impurities, unless otherwise specified. A composition or material "based on X" generally refers to a composition or material in which "X" is the single largest component by weight percentage (%) in the composition or material. This can include compositions or materials having greater than 50 wt% X, as well as compositions or materials having less than 50 wt% X, so long as X is the single largest component based on the overall weight of the composition or material. When a composition or material is said to be "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 the substance.

[0124] As used herein, the term "metal" may refer to a pure elemental metal or an alloy of an elemental metal with one or more other metal or non-metal elements (referred to as "alloying" elements).

Claims

1. A method of manufacturing a battery pack for cycling lithium ions, the method comprising: A precursor mixture is deposited on a metal substrate to form a precursor layer, the precursor mixture comprising: An electroactive negative electrode material comprising silicon, silicon oxide, lithiated silicon suboxide, graphite or a combination thereof, Polymer binders, Nitrate additives, and Aqueous solvents; removing the aqueous solvent from the precursor layer to form a negative electrode on the metal substrate; and The negative electrode and the metal substrate are assembled into a stack including a positive electrode disposed on a positive electrode current collector and a separator interposed between oppositely facing surfaces of the negative electrode and the positive electrode, the positive electrode containing lithium ions.

2. The method of claim 1, wherein the nitrate additive comprises lithium nitrate (LiNO3), sodium nitrate (NaNO3), potassium nitrate (KNO3), copper nitrate (Cu(NO3)2), or a combination thereof.

3. The method of claim 2, wherein the nitrate additive comprises greater than or equal to about 0.01 wt % and less than or equal to about 2 wt % of the negative electrode.

4. The method of claim 1, wherein the nitrate additive comprises LiNO 3 , and wherein LiNO 3 comprises greater than or equal to about 0.05 wt % and less than or equal to about 0.4 wt % of the negative electrode.

5. The method of claim 1, wherein the electroactive negative electrode material further comprises graphite.

6. The method of claim 1, wherein the electroactive negative electrode material comprises greater than or equal to about 80 weight percent and less than or equal to about 97 weight percent of the negative electrode.

7. The method of claim 1, wherein the polymer binder comprises styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), sodium alginate, or a combination thereof, and wherein the polymer binder accounts for greater than or equal to about 2 wt % and less than or equal to about 10 wt % of the negative electrode.

8. The method of claim 1, wherein the precursor mixture further comprises a conductive material, and wherein the conductive material comprises greater than or equal to about 2 wt% and less than or equal to about 10 wt% of the negative electrode.

9. The method according to claim 1, further comprising: impregnating the negative electrode, the positive electrode, and the separator with an electrolyte comprising a lithium salt in a polar aprotic organic solvent, the electrolyte being substantially free of nitrate compounds; and charging the battery by electrically coupling the negative electrode current collector and the positive electrode current collector to a power source so that lithium ions are released from the positive electrode and incorporated into the negative electrode, Wherein during charging of the battery, the nitrate additive reacts with the electroactive negative electrode material to form an electrically insulating and ionically conductive solid interface layer on the surface of the electroactive negative electrode material.

10. The method of claim 9, wherein the polar aprotic organic solvent comprises a mixture of cyclic carbonates and linear carbonates.

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