Non-aqueous electrolyte and battery

Abstract

To address the problem that existing lithium batteries are prone to damage to positive electrode materials under high voltage, the present invention provides a non-aqueous electrolyte and a battery. The non-aqueous electrolyte includes a lithium salt, an organic solvent, and an additive. The additive includes one or more compounds represented by structural formula I, wherein R1 is selected from C or N; R2 is selected from C, N, or S; R3 is selected from a unit containing an acrylate group or a methacrylate group; and R4, R5, and R6 are each independently selected from a substituted or unsubstituted C1-C8 alkyl group, a substituted or unsubstituted C2-C8 alkenyl group, H, or a halogen.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and in particular relates to a non-aqueous electrolyte and a battery. Background Art

[0002] Lithium batteries, due to their high energy density and high voltage, have found increasing application in household appliances, portable electronic devices, and electric vehicles. In recent years, with the continuous development of lithium-ion battery technology, high operating voltage, long cycle life, and high safety have become important performance indicators for lithium-ion batteries. However, excessively high operating voltage in lithium batteries can exacerbate side reactions between the cathode active material and the electrolyte, causing damage to the cathode material, leading to large-scale dissolution of transition metals, resulting in battery capacity decay, and thus affecting battery cycle performance. Therefore, how to ensure stable operation of lithium batteries at high voltages has become a key research focus. Summary of the Invention

[0003] In order to solve the problem that the positive electrode material of existing lithium batteries is easily damaged under high voltage, the present invention provides a non-aqueous electrolyte and a battery.

[0004] The technical solutions adopted by the present invention to solve the above technical problems are as follows:

[0005] In one aspect, the present invention provides a non-aqueous electrolyte comprising a lithium salt, an organic solvent and an additive, wherein the additive comprises one or more compounds represented by structural formula I.

[0006] ,

[0007] Wherein, the R1 is selected from C or N; the R2 is selected from C, N or S; the R3 is selected from a unit containing an acrylate group or a methacrylate group; and the R4, R5, and R6 are each independently selected from a substituted or unsubstituted C1~C8 alkyl, a substituted or unsubstituted C2~C8 alkenyl, H, hydroxyl or halogen.

[0008] Optionally, the mass content of the substance of structural formula I in the non-aqueous electrolyte is 0.5% to 8%.

[0009] Optionally, the mass content of the substance of structural formula I in the non-aqueous electrolyte is 2% to 5%.

[0010] Optionally, the substance of structural formula I includes one or more of structural formulas I-1 to I-6,

[0011] .

[0012] Optionally, the additive further comprises a nitrile additive and fluoroethylene carbonate, wherein the nitrile additive comprises at least one of a C4-C10 dinitrile or a C8-C12 trinitrile.

[0013] Optionally, the nitrile additive includes one or more of succinonitrile, adiponitrile, glutaronitrile, suberonitrile, sebaconitrile, 1,3,5-pentanetricarboxylic acid nitrile, and hexanetrionitrile.

[0014] Optionally, the mass content of the nitrile additive in the non-aqueous electrolyte is 0.1% to 5%;

[0015] And / or, the mass content of the fluoroethylene carbonate in the non-aqueous electrolyte is 0.1% to 10%.

[0016] Optionally, the lithium salt further comprises one or more of lithium hexafluorophosphate, lithium difluorooxalatoborate, lithium tetrafluoroborate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium bis(oxalatoborate);

[0017] And / or, the concentration of the lithium salt is 0.5M~2.0M.

[0018] Optionally, the organic solvent includes at least two of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl propionate, propyl propionate, methyl propionate, ethyl acetate, fluoroethyl acetate, fluoroethyl methyl carbonate, fluorodimethyl carbonate, and fluoropropylene carbonate.

[0019] In another aspect, the present invention provides a battery comprising a positive electrode sheet, a negative electrode sheet, a separator, and the non-aqueous electrolyte as described above.

[0020] Optionally, the positive electrode sheet includes a positive electrode active material, and the positive electrode active material includes one or more of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium iron manganese phosphate, and lithium manganese oxide;

[0021] The negative electrode sheet includes a negative electrode active material, and the negative electrode active material includes natural graphite, artificial graphite, mesophase microcarbon beads, hard carbon, soft carbon, silicon, silicon oxide, silicon-carbon composite, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, TiO2-Li4Ti5O 12 and one or more of Li-Al alloys.

[0022] In the present invention, the compound represented by Structural Formula I in the non-aqueous electrolyte forms a film on the positive electrode surface through ring-opening polymerization, or through double bond polymerization of acrylate or methacrylate groups, forming a polymer film on the positive electrode surface. This allows the non-aqueous electrolyte to inhibit the dissolution of transition metals under high voltage conditions, protecting the positive electrode material from damage, thereby improving the battery's cycle life and energy density. Furthermore, the phosphate groups in the compound represented by Structural Formula I can capture hydroxyl groups and hydrogen protons, thereby enhancing the flame retardant properties of the non-aqueous electrolyte. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] One embodiment of the present invention provides a non-aqueous electrolyte comprising a lithium salt, an organic solvent and an additive, wherein the additive comprises one or more compounds represented by structural formula I.

[0025] ,

[0026] Wherein, the R1 is selected from C or N; the R2 is selected from C, N or S; the R3 is selected from a unit containing an acrylate group or a methacrylate group; and the R4, R5, and R6 are each independently selected from a substituted or unsubstituted C1~C8 alkyl, a substituted or unsubstituted C2~C8 alkenyl, H, hydroxyl or halogen.

[0027] In the present invention, the compound represented by Structural Formula I in the non-aqueous electrolyte forms a film on the positive electrode surface through ring-opening polymerization, or through double bond polymerization of acrylate or methacrylate groups, forming a polymer film on the positive electrode surface. This allows the non-aqueous electrolyte to inhibit the dissolution of transition metals under high voltage conditions, protecting the positive electrode material from damage, thereby improving the battery's cycle life and energy density. Furthermore, the phosphate groups in the compound represented by Structural Formula I can capture hydroxyl groups and hydrogen protons, thereby enhancing the flame retardant properties of the non-aqueous electrolyte.

[0028] In some embodiments, the mass content of the substance of structural formula I in the non-aqueous electrolyte is 0.5% to 8%. Electrolytes containing the substance of structural formula I within this range can improve the high-temperature and high-voltage performance and safety of battery cells, reduce impedance, and increase the cycle life of the battery.

[0029] In one embodiment, the mass content of the substance of structural formula I includes but is not limited to 0.5%, 0.8%, 1.1%, 1.4%, 1.7%, 2%, 2.3%, 2.6%, 2.9%, 3.2%, 3.5%, 3.8%, 4.1%, 4.4%, 4.7%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5% or 8%.

[0030] In a preferred embodiment, the mass content of the substance of structural formula I in the non-aqueous electrolyte is 2% to 5%. Non-aqueous electrolytes containing the substance of structural formula I within this range can further improve the high-temperature and high-pressure performance and safety of the battery, and increase the cycle life of the battery.

[0031] In some embodiments, the substance of structural formula I includes one or more of structural formulas I-1 to I-6,

[0032] .

[0033] By selecting the above additives, the high temperature and high pressure performance and safety performance of the battery cell can be further improved, and the flame retardant performance of the electrolyte can be improved.

[0034] Furthermore, the preparation method of the substance of structural formula I-1 comprises the following steps:

[0035] 2,4-Dihydroxypyridine, acrylic acid, and hypophosphorous acid are used as raw materials, and triethylamine is used as a catalyst. 2,4-Dihydroxypyridine is mixed with an equal amount of triethylamine and stirred to obtain a mixed solution. Acrylic acid is slowly added dropwise to the mixed solution at a certain reaction temperature. After the addition is complete, hypophosphorous acid is slowly added dropwise with constant stirring. After the addition is complete, stirring is continued at room temperature for 5 hours, and the reactant is filtered to obtain the substance represented by Formula I-1.

[0036] The preparation method of the substance of structural formula I-2 comprises the following steps:

[0037] 2,4-Dihydroxypyridine, acrylic acid, and difluorophosphoric acid are used as raw materials, and triethylamine is used as a catalyst. 2,4-Dihydroxypyridine is mixed with an equal amount of triethylamine and stirred to obtain a mixed solution. Acrylic acid is slowly added dropwise to the mixed solution at a certain reaction temperature. After the addition is complete, difluorophosphoric acid is slowly added dropwise with uniform stirring. After the addition is complete, stirring is continued at room temperature for 5 hours. The reactant is filtered to obtain the substance represented by Formula I-2.

[0038] The preparation method of the substance of structural formula I-3 comprises the following steps:

[0039] 2,4-Dihydroxypyridine, acrylic acid, and monofluorophosphoric acid are used as raw materials, and triethylamine is used as a catalyst. 2,4-Dihydroxypyridine is mixed with an equal amount of triethylamine and stirred to obtain a mixed solution. Acrylic acid is slowly added dropwise to the mixed solution at a certain reaction temperature. After the addition is complete, monofluorophosphoric acid is slowly added dropwise with uniform stirring. After the addition is complete, stirring is continued at room temperature for 5 hours. The reactant is filtered to obtain the substance represented by Formula I-3.

[0040] The preparation method of the substance of structural formula I-4 comprises the following steps:

[0041] 2,4-Dihydroxypyridine, acrylic acid, and dimethylphosphonic acid are used as raw materials, and triethylamine is used as a catalyst. 2,4-Dihydroxypyridine is mixed with an equal amount of triethylamine and stirred to obtain a mixed solution. Acrylic acid is slowly added dropwise to the mixed solution at a certain reaction temperature. After the addition is complete, dimethylphosphonic acid is slowly added dropwise with uniform stirring. After the addition is complete, stirring is continued at room temperature for 5 hours. The reactant is filtered to obtain the substance represented by Formula I-4.

[0042] The preparation method of the substance of structural formula I-5 comprises the following steps:

[0043] 2,4-Dihydroxypyridine, methacrylic acid, and dimethylphosphonic acid are used as raw materials, and triethylamine is used as a catalyst. 2,4-Dihydroxypyridine is mixed with an equal amount of triethylamine and stirred to obtain a mixed solution. Methacrylic acid is slowly added dropwise to the mixed solution at a certain reaction temperature. After the addition is complete, dimethylphosphonic acid is slowly added dropwise with uniform stirring. After the addition is complete, stirring is continued at room temperature for 5 hours. The reaction mixture is filtered to obtain the substance shown in I-5.

[0044] The preparation method of the substance of structural formula I-6 comprises the following steps:

[0045] 2,4-Dihydroxypyridine, methacrylic acid, and diethylphosphonic acid are used as raw materials, and triethylamine is used as a catalyst. 2,4-Dihydroxypyridine is mixed with an equal amount of triethylamine and stirred to obtain a mixed solution. Methacrylic acid is slowly added dropwise to the mixed solution at a certain reaction temperature. After the addition is complete, diethylphosphonic acid is slowly added dropwise with constant stirring. After the addition is complete, stirring is continued at room temperature for 5 hours. The reaction mixture is filtered to obtain the substance shown in I-6.

[0046] In certain embodiments, the additive further comprises a nitrile additive and fluoroethylene carbonate, wherein the nitrile additive comprises at least one of a dinitrile of C4~C10 or a trinitrile of C8~C12. By adding the nitrile additive to the nonaqueous electrolyte, it is convenient to form a film at the positive electrode, thereby further protecting the positive electrode. By adding fluoroethylene carbonate, a LiF-rich SEI is formed at the negative electrode, thereby further protecting the negative electrode. The nitrile additive, fluoroethylene carbonate, and the substance of structural formula I are used in combination to better protect the positive and negative electrodes, improve the cycle performance of the battery under high voltage, and enhance the energy density of the battery.

[0047] In some embodiments, the nitrile additive includes one or more of succinonitrile (SN), adiponitrile (ADN), glutaronitrile, suberonitrile, sebaconinitrile, 1,3,5-pentanetricarboxylic acid nitrile, and hexanetricarbonitrile (HTCN). The use of these nitrile additives facilitates film formation on the positive electrode, prevents side reactions between the positive electrode and the electrolyte, improves electrolyte stability, and further protects the positive electrode.

[0048] In some embodiments, the mass content of the nitrile additive in the non-aqueous electrolyte is 0.1% to 5%.

[0049] The mass content of the fluoroethylene carbonate in the non-aqueous electrolyte is 0.1% to 10%.

[0050] By regulating the content of nitrile additives and fluoroethylene carbonate, the occurrence of side reactions in the electrolyte during the charge and discharge process can be inhibited, the positive and negative electrodes can be better protected, the cycle performance of the battery at high voltage can be improved, and the energy density of the battery can be increased.

[0051] In a specific embodiment, the content of the nitrile additive includes, but is not limited to, 0.1%, 1%, 2%, 3%, 3.5%, 4%, 4.5%, or 5%. The mass content of the fluoroethylene carbonate includes, but is not limited to, 0.1%, 1%, 2%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 8%, 9%, or 10%.

[0052] In some embodiments, the lithium salt further comprises one or more of lithium hexafluorophosphate (LiPF6), lithium difluorooxalatoborate (LiODFB), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(oxalatoborate) (LiBOB). By selecting the above ionizable lithium salts, the amount of lithium ions that can migrate in the electrolyte is guaranteed.

[0053] In some embodiments, the concentration of the lithium salt is 0.5 M to 2.0 M. The concentration of the lithium salt in the electrolyte is not particularly limited, but when the lithium salt content is less than 0.5 M, the number of mobile lithium ions in the electrolyte is insufficient. When the lithium salt content is greater than 2 M, the viscosity of the electrolyte may increase, resulting in an increase in electrolyte impedance, which reduces the lithium ion migration rate and may reduce battery performance.

[0054] In some embodiments, the organic solvent includes at least two of ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethyl propionate (EP), propyl propionate (PP), methyl propionate (MP), ethyl acetate (EA), fluoroethyl acetate (DFEA), fluoroethyl methyl carbonate (FEMC), fluorodimethyl carbonate (FDMC), and fluoropropylene carbonate (FPC).

[0055] Based on the mass of the non-aqueous electrolyte being 100%, the content of the organic solvent is 70% to 90%. By regulating the content of the organic solvent, the viscosity of the electrolyte is improved to ensure the migration rate of lithium ions in the electrolyte.

[0056] In one embodiment, the content of the organic solvent is 70%, 75%, 80%, 85% or 90%.

[0057] In another aspect, an embodiment of the present invention provides a battery comprising a positive electrode sheet, a negative electrode sheet, a separator, and the non-aqueous electrolyte described in any of the above embodiments. By selecting the non-aqueous electrolyte described in the above embodiments, the positive and negative electrodes of the battery operating at high voltage are protected, side reactions between the positive electrode and the wastewater electrolyte are prevented, and the battery's cycle life and energy density are improved.

[0058] In some embodiments, the positive electrode sheet includes a positive electrode active material, and the positive electrode active material includes one or more of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium iron manganese phosphate, and lithium manganese oxide;

[0059] The negative electrode sheet includes a negative electrode active material, and the negative electrode active material includes natural graphite, artificial graphite, mesophase microcarbon beads, hard carbon, soft carbon, silicon, silicon oxide, silicon-carbon composite, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, TiO2-Li4Ti5O 12 and one or more of Li-Al alloys.

[0060] The present invention is further described below with reference to the following examples.

[0061] Example 1

[0062] This embodiment is used to illustrate the non-aqueous electrolyte and battery disclosed in the present invention, and includes the following steps:

[0063] Preparation of non-aqueous electrolyte

[0064] EC / PC / DEC / PP were mixed at a ratio of 1:1:1:1 in a glove box with a water and oxygen content of <10 ppm, and 1 M LiPF6, 2% of an additive represented by structural formula I-1, 2% of HTCN, and 5% of FEC were added to obtain a non-aqueous electrolyte.

[0065] Production of positive electrode:

[0066] The positive electrode active material lithium cobalt oxide, conductive agent CNT, and adhesive PVDF are fully stirred and mixed in NMP solvent at a weight ratio of 97:1.5:1.5. The slurry is coated on aluminum foil and then dried, cold pressed, slit, sheeted, welded to the tabs, and glued to make a positive electrode sheet that meets the requirements. Other positive electrode materials such as lithium manganese oxide (LiMn2O4), 532 ternary (LiNi 0.5 Co 0.3 Mn 0.2 ) were prepared in a similar manner.

[0067] Production of negative electrode:

[0068] Graphite (the negative electrode active material), conductive agent SP, thickener CMC, and binder SBR are thoroughly mixed in a suitable amount of deionized water at a mass ratio of 96.3:1:1.2:1.5 to form a uniform negative electrode slurry. This slurry is then applied to the negative electrode current collector copper foil. A negative electrode sheet that meets the requirements is produced through drying, cold pressing, slitting, sheeting, tab welding, and adhesive application. Other negative electrode materials, such as lithium titanate, are prepared similarly.

[0069] Production of lithium-ion batteries:

[0070] The positive electrode sheet, separator, and negative electrode sheet are wound and stacked to form a bare cell. The bare cell is then placed in a pre-punched aluminum-plastic film and sealed on the top and sides. After high-temperature baking, liquid injection, static aging, formation, capacity grading, and testing, the battery is complete.

[0071] Example 2-23

[0072] The examples are used to illustrate the non-aqueous electrolyte and battery disclosed in the present invention, and include most of the operating steps in Example 1, except that the formulation in Table 1 is used.

[0073] Comparative Examples 1-3

[0074] The comparative example is used to compare and illustrate the non-aqueous electrolyte and battery disclosed in the present invention, and includes most of the operating steps in Example 1, except that the formula in Table 1 is used.

[0075] Table 1

[0076]

[0077] Performance Testing

[0078] 1. The lithium-ion batteries prepared in the above examples and comparative examples were subjected to the following performance tests:

[0079] Test 1: Charge to 4.53V at 1C constant current and constant voltage at 25℃, cut-off current 0.05C, let stand for 10min, discharge to 3.0V at 1C, record discharge capacity C0 as initial capacity, repeat for 800 cycles. The final capacity C of 800 cycles is 800 , then the capacity retention rate = C 800 / C0.

[0080] Test 2: Charge to 4.53V at 0.5C constant current and constant voltage at 45℃, cut off current at 0.05C, let stand for 10min, discharge to 3.0V at 0.5C, record discharge capacity C0 as initial capacity, repeat for 500 cycles. The final capacity C after 500 cycles is 500 , then the capacity retention rate = C 500 / C0.

[0081] The test results are shown in Table 2.

[0082] Table 2

[0083]

[0084] The test results in Table 2 show that, by adding the non-aqueous electrolyte to the lithium-ion battery, the embodiment of the present invention can significantly improve the room temperature cycling performance and high temperature cycling performance of the lithium-ion battery at high voltage.

[0085] The test results of Examples 1-6 and Comparative Example 1 show that the degree of improvement in the room temperature and high temperature cycle performance of lithium-ion batteries with different structures of the substance of Structural Formula I varies, but is significantly superior to Comparative Example 1, which does not include the substance of Structural Formula I. Combining Examples 1 and 7-21, it can be found that the content of the substance of Structural Formula I, the type and content of the nitrile additive, and the content of FEC also affect the battery's cycle performance to varying degrees. Furthermore, as can be seen from Examples 1 and 7-11, it can be found that either too low or too high a content of the substance of Structural Formula I is detrimental to improving the cycle performance. Too low a content of the substance of Structural Formula I provides insufficient protection for the positive electrode, resulting in rapid capacity decay. Too high a content of the substance of Structural Formula I can result in a larger internal impedance of the battery, which can also deteriorate the battery's cycle performance. Too high a content of the nitrile additive can also result in excessive internal impedance, which is detrimental to the battery's cycle performance. Too low a content of the nitrile additive can provide insufficient protection for the positive electrode, leading to transition metal dissolution and deposition at the negative electrode, which can also deteriorate the battery's cycle performance. If the content of fluoroethylene carbonate is too high, it will cause serious gas production inside the battery cell. If the content is too low, the SEI will be unstable and the cycle decay will be faster.

[0086] In combination with Example 1, Example 16, Example 20, Example 22 and Comparative Examples 1-3, it can be seen that the use of nitrile additives, fluoroethylene carbonate and the substance of structural formula I in combination can better protect the positive and negative electrodes, improve the cycle performance of the battery at high voltage, and increase the energy density of the battery.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A non-aqueous electrolyte, characterized in that It includes a lithium salt, an organic solvent and an additive, wherein the additive includes one or more compounds shown in structural formula I, wherein structural formula I is ， wherein R1 is selected from C or N; R2 is selected from C, N or S; R3 is selected from a unit containing an acrylate group or a methacrylate group; and R4, R5, and R6 are each independently selected from a substituted or unsubstituted C1-C8 alkyl group, a substituted or unsubstituted C2-C8 alkenyl group, H, hydroxyl group, or halogen; The mass content of the substance of structural formula I in the non-aqueous electrolyte is 0.5% to 8%.

2. The non-aqueous electrolyte according to claim 1, characterized in that The mass content of the substance of structural formula I in the non-aqueous electrolyte is 2% to 5%.

3. The non-aqueous electrolyte according to claim 1 or 2, characterized in that The substance of structural formula I includes one or more of structural formulas I-1 to I-6, 。 4. The non-aqueous electrolyte according to claim 1, wherein The additives further include nitrile additives and fluoroethylene carbonate, wherein the nitrile additives include at least one of C4-C10 dinitriles or C8-C12 trinitriles.

5. The non-aqueous electrolyte according to claim 4, characterized in that The nitrile additive includes one or more of succinonitrile, adiponitrile, glutaronitrile, suberonitrile, sebaconitrile, 1,3,5-pentanetricarboxylic acid nitrile and hexanetrionitrile.

6. The non-aqueous electrolyte according to claim 4, characterized in that The mass content of the nitrile additive in the non-aqueous electrolyte is 0.1% to 5%; And / or, the mass content of the fluoroethylene carbonate in the non-aqueous electrolyte is 0.1% to 10%.

7. The non-aqueous electrolyte according to claim 1, characterized in that The lithium salt further comprises one or more of lithium hexafluorophosphate, lithium difluorooxalatoborate, lithium tetrafluoroborate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium bis(oxalatoborate); and / or, the concentration of the lithium salt is 0.5M~2.0M; And / or, the organic solvent includes at least two of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl propionate, propyl propionate, methyl propionate, ethyl acetate, fluoroethyl acetate, fluoroethyl methyl carbonate, fluorodimethyl carbonate, and fluoropropylene carbonate.

8. A battery, characterized in that: The invention comprises a positive electrode sheet, a negative electrode sheet, a separator and the non-aqueous electrolyte according to any one of claims 1 to 7.

9. The battery according to claim 8, characterized in that The positive electrode sheet includes a positive electrode active material, and the positive electrode active material includes one or more of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium iron manganese phosphate, and lithium manganese oxide; The negative electrode sheet includes a negative electrode active material, and the negative electrode active material includes natural graphite, artificial graphite, mesophase microcarbon beads, hard carbon, soft carbon, silicon, silicon oxide, silicon-carbon composite, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, TiO2-Li4Ti5O 12 and one or more of Li-Al alloys.

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