Negative-electrode-free lithium ion battery and preparation method therefor

Abstract

A negative-electrode-free lithium ion battery and a preparation method therefor. The battery comprises a positive electrode and a negative electrode, wherein the positive electrode includes a positive electrode metal current collector and a positive electrode slurry layer provided on the surface of the positive electrode metal current collector, and the positive electrode slurry layer contains a positive electrode lithium-supplementing agent; and the negative electrode includes a negative electrode metal current collector and a solid electrolyte layer provided on the surface of the negative electrode metal current collector, and the raw materials for preparing the solid electrolyte layer include a solid electrolyte and a solid electrolyte layer binder. All of the lithium sources in the battery are provided by the positive electrode, and there is no active substance on the negative electrode side, which can compensate for the irreversible loss of lithium, and improve the problems of the low coulombic efficiency and short cycle life of the negative electrode-free battery.

Description

A negative electrode-free lithium ion battery and its preparation method Technical Field

[0001] The present invention belongs to the technical field of lithium ion batteries, and in particular relates to a negative electrode-free lithium ion battery and a preparation method thereof. Background Art

[0002] In recent years, due to the limited energy density of lithium-ion batteries, researchers have begun to try to use high-capacity, low-voltage lithium metal anodes to construct high-energy-density lithium metal batteries. However, the use of excessive lithium metal anodes usually leads to a significant decrease in battery energy density. At the same time, excessive lithium will continuously consume the electrolyte, forming high-resistance byproducts, leading to battery failure. In addition, serious lithium dendrite problems may induce battery safety issues. The anode-free battery configuration can avoid the generation of excessive lithium, thereby greatly improving battery safety and energy density. Anode-free solid-state lithium batteries have broad application prospects in next-generation energy storage systems, especially mobile energy storage systems, due to their ultra-high energy density, higher safety and longer calendar life.

[0003] However, due to the limited lithium source inside the battery and the poor reversibility of metallic lithium deposition, negative electrode-free batteries face problems such as low coulombic efficiency and short cycle life.

[0004] Summary of the Invention

[0005] The present invention aims to address at least one of the aforementioned technical problems in the prior art. To this end, the present invention provides a negative electrode-free lithium-ion battery, comprising a positive electrode and a negative electrode. All lithium within the battery is provided by the positive electrode, and the negative electrode contains no active material. This compensates for irreversible lithium loss, thereby improving the low coulombic efficiency and short cycle life of negative electrode-free batteries.

[0006] The present invention also provides a method for preparing a negative electrode-free lithium ion battery.

[0007] A first aspect of the present invention provides a negative electrode-free lithium ion battery, comprising:

[0008] A positive electrode comprising a positive electrode metal current collector and a positive electrode slurry layer disposed on the surface of the positive electrode metal current collector, wherein the positive electrode slurry layer contains a positive electrode lithium supplement;

[0009] The negative electrode comprises a negative electrode metal current collector and a solid electrolyte layer arranged on the surface of the negative electrode metal current collector, wherein the solid electrolyte layer contains a solid electrolyte and a solid electrolyte layer binder.

[0010] One of the technical solutions of the present invention regarding the negative electrode-free lithium ion battery has at least the following beneficial effects:

[0011] In the cathode-free lithium-ion battery of the present invention, the positive electrode includes a positive metal current collector and a positive electrode slurry layer disposed on the surface of the positive metal current collector. The positive electrode slurry layer contains a positive electrode lithium replenisher that can compensate for the loss of lithium ions from the solid-state electrolyte reaction at the negative electrode. The negative electrode includes a negative metal current collector and a solid electrolyte layer disposed on the surface of the negative metal current collector. The solid electrolyte layer contains a solid electrolyte and a solid electrolyte layer binder. The solid electrolyte has electrolytic affinity and can induce uniform lithium ion deposition, reducing the formation of lithium dendrites. When the solid electrolyte on the negative electrode current collector is combined with the positive electrode lithium replenisher, the structure of the positive electrode material is more stable, and the two synergistically improve the long-cycle performance of the cathode-free battery.

[0012] According to some embodiments of the present invention, the positive electrode slurry layer further contains a positive electrode active material, a conductive agent, a positive electrode slurry layer binder, and a solvent.

[0013] According to some embodiments of the present invention, the positive electrode active material includes at least one of lithium cobalt oxide, lithium manganese oxide, and lithium iron phosphate.

[0014] According to some embodiments of the present invention, the positive electrode active material includes a ternary material.

[0015] According to some embodiments of the present invention, the amount of the positive electrode active material added to the raw materials for preparing the positive electrode slurry layer is 90 wt % to 97 wt %.

[0016] According to some embodiments of the present invention, the positive electrode lithium supplement includes at least one of Li5FeO4, Li2NiO2, Li2O, Li6CoO4 and Li2CuO2.

[0017] According to some embodiments of the present invention, the positive electrode lithium supplement is added in an amount of 0.1 wt % to 5 wt % in the raw materials for preparing the positive electrode slurry layer.

[0018] According to some embodiments of the present invention, in the positive electrode slurry layer, the conductive agent includes at least one of acetylene black, graphene, carbon fiber, and carbon nanotubes.

[0019] According to some embodiments of the present invention, the conductive agent is added in an amount of 0.1 wt % to 3 wt % in the raw materials for preparing the positive electrode slurry layer.

[0020] According to some embodiments of the present invention, in the positive electrode slurry layer, the positive electrode slurry layer binder includes polyvinylidene fluoride.

[0021] According to some embodiments of the present invention, the binder for the positive electrode slurry layer is added in an amount of 0.1 wt % to 2 wt % in the raw materials for preparing the positive electrode slurry layer.

[0022] According to some embodiments of the present invention, in the positive electrode slurry layer, the solvent includes N-methyl-2-pyrrolidone.

[0023] According to some embodiments of the present invention, the solid electrolyte layer binder includes at least one of polyvinyl alcohol, polyvinylidene fluoride, and polyethylene oxide.

[0024] In the solid electrolyte layer binder, taking polyvinyl alcohol as an example, the OH functional groups on the surface of polyvinyl alcohol will react with Li + The reaction forms CO-Li bonds for ion conduction, which can make lithium ions deposit evenly on the surface of the electrode, reduce lithium dendrites, improve the stability and rate performance of the battery during the cycle, and at the same time increase the energy density of the battery.

[0025] According to some embodiments of the present invention, the solid electrolyte layer binder is added in an amount of 0.1 wt % to 3 wt % in the raw materials for preparing the solid electrolyte layer.

[0026] When the addition amount of the solid electrolyte layer binder in the raw materials for preparing the solid electrolyte layer is 0.1wt% to 3wt%, the solid electrolyte can better interact with the solid electrolyte layer binder, so that lithium ions are evenly deposited on the surface of the electrode, reducing lithium dendrites and improving battery performance; beyond this range, the solid electrolyte coating effect on the copper foil surface is poor, lithium ions are unevenly deposited on the surface of the electrode, the risk of lithium plating increases, and the battery safety risk increases.

[0027] According to some embodiments of the present invention, in the negative electrode, the solid electrolyte layer further contains a conductive agent and a solvent.

[0028] According to some embodiments of the present invention, the solid electrolyte includes lithium aluminum titanium phosphate, lithium lanthanum zirconium oxide, lithium lanthanum zirconium titanate, lithium aluminum germanium phosphate, lithium lanthanum titanate and Li 10 GeP2S 12 At least one of .

[0029] According to some embodiments of the present invention, the solid electrolyte is added in an amount of 80 wt % to 99 wt % in the raw materials for preparing the solid electrolyte layer.

[0030] According to some embodiments of the present invention, the solid electrolyte is added in an amount of 90 wt % to 97 wt % in the raw materials for preparing the solid electrolyte layer.

[0031] If the content of solid electrolyte is too low, the lithium ions on the positive electrode side will precipitate on the negative electrode side.

[0032] According to some embodiments of the present invention, in the solid electrolyte layer, the conductive agent includes at least one of acetylene black, graphene, carbon fiber, and carbon nanotubes.

[0033] According to some embodiments of the present invention, the conductive agent is added in an amount of 0.1 wt % to 3 wt % in the raw materials for preparing the solid electrolyte layer.

[0034] According to some embodiments of the present invention, the alcoholysis degree of the solid electrolyte layer binder is 75% to 85%.

[0035] The test method for alcoholysis degree is as follows: weigh 0.5-1.0g of sample and dissolve it, then add a known excess of NaOH solution to make the unhydrolyzed part undergo saponification reaction, then add a known excess of H2SO4, and then use a certain concentration of NaOH standard solution to neutralize the excess H2SO4, calculate the mass fraction A of residual acetate by the amount of NaOH consumed, and finally calculate the alcoholysis degree by the formula B (alcoholysis degree) = 100-44.05A / (60.05-0.42A).

[0036] The alcoholysis degree of the solid electrolyte layer binder is 75% to 85%, which can ensure the adhesion and have appropriate OH functional groups to react with Li + The reaction forms CO-Li bonds for ion conduction, allowing lithium ions to be deposited more evenly on the electrode surface. If the viscosity is too high, the binder solubility will be low, while if it is too low, the bonding strength will be reduced due to the low cohesive force.

[0037] According to some embodiments of the present invention, in the solid electrolyte layer, the solvent includes N-methyl-2-pyrrolidone.

[0038] The second aspect of the present invention provides a method for preparing the negative electrode-free lithium ion battery, comprising winding a separator with the positive electrode and the negative electrode to obtain a bare cell, injecting an electrolyte and then encapsulating to obtain the negative electrode-free lithium ion battery.

[0039] A technical solution of the present invention in the method for preparing a negative electrode-free lithium ion battery has at least the following beneficial effects:

[0040] The negative electrode-free lithium ion battery of the present invention does not require special equipment and complex process control for its preparation, has undemanding reaction conditions, has readily available raw materials, has low production costs, and is easy to industrialize.

[0041] According to some embodiments of the present invention, the separator may be a conventional PE-based separator.

[0042] According to some embodiments of the present invention, the thickness of the separator is 7 μm to 10 μm.

[0043] According to some embodiments of the present invention, the electrolyte may be a conventional electrolyte, specifically comprising a lithium salt, an organic solvent, and an additive, wherein the lithium salt comprises at least one of lithium hexafluorophosphate (LiPF6), lithium difluorophosphate (LiPF2O2), lithium difluorooxalatoborate (LiODFB), lithium tetrafluoroborate (LiBF4), lithium difluorobis(oxalatophosphate) (LiDFBOP), lithium bis(trifluoromethylsulfonyl)imide (LiTFSi), or lithium bis(fluorosulfonyl)imide (LiFSi).

[0044] The organic solvent includes at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ethyl propionate (EP), propyl propionate (PP), ethyl acetate (EA) or gamma-butyrolactone (GBL), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (EP), n-propyl propionate (PP), methyl propionate (MP, CAS: 554-12-1), methyl butyrate (MB) and ethyl butyrate (EB).

[0045] The additive includes at least one of ethylene carbonate (VC), 1,3-propane sultone (PS), diethylene sulfate (DTD), maleic anhydride, succinic anhydride, succinonitrile (SN), adiponitrile (ADN), ethylene glycol bis(propionitrile) ether (EGBE) or hexanetrionitrile (HTCN). DETAILED DESCRIPTION

[0046] The following are specific embodiments of the present invention, and the technical solutions of the present invention are further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0047] In some embodiments of the present invention, the present invention provides a negative electrode-free lithium ion battery, comprising:

[0048] A positive electrode comprising a positive electrode metal current collector and a positive electrode slurry layer disposed on the surface of the positive electrode metal current collector, wherein the positive electrode slurry layer contains a positive electrode lithium supplement;

[0049] The negative electrode comprises a negative electrode metal current collector and a solid electrolyte layer arranged on the surface of the negative electrode metal current collector, wherein the solid electrolyte layer contains a solid electrolyte and a solid electrolyte layer binder.

[0050] It can be understood that in the negative electrode-free lithium ion battery of the present invention, the positive electrode includes a positive electrode metal current collector and a positive electrode slurry layer provided on the surface of the positive electrode metal current collector. The positive electrode slurry layer contains a positive electrode lithium replenisher, which can compensate for the loss of lithium ions caused by the negative electrode solid electrolyte reaction. The negative electrode includes a negative electrode metal current collector and a solid electrolyte layer provided on the surface of the negative electrode metal current collector. The solid electrolyte layer contains a solid electrolyte and a solid electrolyte layer binder. The solid electrolyte has electrolytic affinity and can induce uniform lithium ion deposition, reducing the formation of lithium dendrites. When the solid electrolyte on the negative electrode current collector is combined with the positive electrode lithium replenisher, the structure of the positive electrode material is more stable, and the two work together to improve the long-cycle performance of the negative electrode-free lithium ion battery.

[0051] In order to further improve the uniformity of lithium ion deposition on the surface of the solid electrolyte and reduce the generation of lithium dendrites, the binder containing OH functional groups in the solid electrolyte layer will react with Li + The reaction forms CO-Li bonds for ion conduction, which can make lithium ions deposit evenly on the surface of the electrode, reduce lithium dendrites, improve the stability and rate performance of the battery during the cycle, and at the same time increase the energy density of the battery.

[0052] In some embodiments of the present invention, the positive electrode slurry layer further contains a positive electrode active material, a conductive agent, a positive electrode slurry layer binder, and a solvent.

[0053] In some embodiments of the present invention, the positive electrode active material includes at least one of lithium cobalt oxide, lithium manganese oxide, and lithium iron phosphate.

[0054] In some embodiments of the present invention, the positive electrode active material includes a ternary material.

[0055] In some embodiments of the present invention, the amount of the positive electrode active material added to the raw materials for preparing the positive electrode slurry layer is 90 wt % to 97 wt %.

[0056] In some embodiments of the present invention, the positive electrode lithium supplement includes at least one of Li5FeO4, Li2NiO2, Li2O, Li6CoO4 and Li2CuO2.

[0057] In some embodiments of the present invention, the amount of the positive electrode lithium supplement agent added to the raw materials for preparing the positive electrode slurry layer is 0.1 wt % to 5 wt %.

[0058] In some embodiments of the present invention, in the positive electrode slurry layer, the conductive agent includes at least one of acetylene black, graphene, carbon fiber, and carbon nanotubes.

[0059] In some embodiments of the present invention, the amount of the conductive agent added to the raw materials for preparing the positive electrode slurry layer is 0.1 wt % to 3 wt %.

[0060] In some embodiments of the present invention, the positive electrode slurry layer binder includes polyvinylidene fluoride.

[0061] In some embodiments of the present invention, the amount of the binder added to the raw materials for preparing the positive electrode slurry layer is 0.1 wt % to 2 wt %.

[0062] In some embodiments of the present invention, in the positive electrode slurry layer, the solvent includes N-methyl-2-pyrrolidone.

[0063] In some embodiments of the present invention, in the negative electrode, the solid electrolyte layer binder includes at least one of polyvinyl alcohol, polyvinylidene fluoride, and polyethylene oxide.

[0064] It can be understood that, taking polyvinyl alcohol as an example, the OH functional groups on the surface of polyvinyl alcohol will react with Li + The reaction forms CO-Li bonds for ion conduction, which can make lithium ions deposit evenly on the surface of the electrode, reduce lithium dendrites, improve the stability and rate performance of the battery during the cycle, and at the same time increase the energy density of the battery.

[0065] In some embodiments of the present invention, the amount of the solid electrolyte layer binder added to the raw materials for preparing the solid electrolyte layer is 0.1 wt% to 3 wt%.

[0066] It should be noted that when the addition amount of the solid electrolyte layer binder in the raw materials for preparing the solid electrolyte layer is 0.1wt% to 3wt%, the solid electrolyte can better interact with the solid electrolyte layer binder, so that lithium ions are evenly deposited on the surface of the electrode, reducing lithium dendrites and improving battery performance; beyond this range, the solid electrolyte coating effect on the copper foil surface is poor, lithium ions are unevenly deposited on the surface of the electrode, the risk of lithium plating increases, and the battery safety risk increases.

[0067] In some embodiments of the present invention, in the negative electrode, the solid electrolyte layer further contains a conductive agent and a solvent.

[0068] In some embodiments of the present invention, the solid electrolyte includes lithium aluminum titanium phosphate, lithium lanthanum zirconium oxide, lithium lanthanum zirconium titanium oxide, lithium aluminum germanium phosphate, lithium lanthanum titanium oxide and Li 10 GeP2S 12 At least one of .

[0069] In some embodiments of the present invention, the amount of solid electrolyte added to the raw materials for preparing the solid electrolyte layer is 80 wt % to 99 wt %.

[0070] In some embodiments of the present invention, the amount of solid electrolyte added to the raw materials for preparing the solid electrolyte layer is 90 wt % to 97 wt %.

[0071] If the content of solid electrolyte is too low, the lithium ions on the positive electrode side will precipitate on the negative electrode side.

[0072] In some embodiments of the present invention, in the solid electrolyte layer, the conductive agent includes at least one of acetylene black, graphene, carbon fiber, and carbon nanotubes.

[0073] In some embodiments of the present invention, the amount of the conductive agent added to the raw materials for preparing the solid electrolyte layer is 0.1 wt% to 3 wt%.

[0074] In some embodiments of the present invention, the alcoholysis degree of the solid electrolyte layer binder is 75% to 85%.

[0075] The alcoholysis degree of the solid electrolyte layer binder is 75% to 85%, which can ensure the adhesion and have appropriate OH functional groups to react with Li + The reaction forms CO-Li bonds for ion conduction, allowing lithium ions to be deposited more evenly on the electrode surface. If the viscosity is too high, the binder solubility will be low, while if it is too low, the bonding strength will be reduced due to the low cohesive force.

[0076] In some embodiments of the present invention, in the solid electrolyte layer, the solvent includes N-methyl-2-pyrrolidone.

[0077] In some other embodiments of the present invention, the present invention provides a method for preparing a negative electrode-free lithium ion battery, comprising winding a separator with a positive electrode and a negative electrode to obtain a bare battery cell, injecting an electrolyte and then packaging to obtain the negative electrode-free lithium ion battery of the present invention.

[0078] It can be understood that the preparation of the negative electrode-free lithium ion battery of the present invention does not require special equipment and complex process control, the reaction conditions are not harsh, the raw materials are easily available, the production cost is low, and it is easy to industrialize.

[0079] In some embodiments of the present invention, the separator may be a conventional PE-based separator.

[0080] In some embodiments of the present invention, the thickness of the separator is 7 μm to 10 μm.

[0081] In some embodiments of the present invention, the electrolyte may be a conventional electrolyte, specifically comprising a lithium salt, an organic solvent, and an additive, wherein the lithium salt comprises at least one of lithium hexafluorophosphate (LiPF6), lithium difluorophosphate (LiPF2O2), lithium difluorooxalatoborate (LiODFB), lithium tetrafluoroborate (LiBF4), lithium difluorobis(oxalatophosphate) (LiDFBOP), lithium bis(trifluoromethylsulfonyl)imide (LiTFSi), or lithium bis(fluorosulfonyl)imide (LiFSi).

[0082] In some embodiments of the present invention, the solvent includes at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ethyl propionate (EP), propyl propionate (PP), ethyl acetate (EA) or gamma-butyrolactone (GBL), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (EP), n-propyl propionate (PP), methyl propionate (MP, CAS: 554-12-1), methyl butyrate (MB) and ethyl butyrate (EB).

[0083] In some embodiments of the present invention, the additive includes at least one of ethylene carbonate (VC), 1,3-propane sultone (PS), diethylene sulfate (DTD), maleic anhydride, succinic anhydride, succinonitrile (SN), adiponitrile (ADN), ethylene glycol bis(propionitrile) ether (EGBE) or hexanetrionitrile (HTCN).

[0084] The technical solution of the present invention will be better understood with reference to specific embodiments below.

[0085] Example 1

[0086] This embodiment prepares a negative electrode-free lithium ion battery, comprising:

[0087] The positive electrode comprises a positive electrode metal current collector and a positive electrode slurry layer disposed on the surface of the positive electrode metal current collector, wherein the positive electrode slurry layer contains a positive electrode lithium supplement;

[0088] The negative electrode comprises a negative electrode metal current collector and a solid electrolyte layer arranged on the surface of the negative electrode metal current collector. The solid electrolyte layer contains a solid electrolyte and a solid electrolyte layer binder, polyvinyl alcohol.

[0089] In the positive electrode:

[0090] The positive electrode slurry layer contains a positive electrode active material, a positive electrode lithium supplement, a conductive agent, a binder and a solvent.

[0091] The positive electrode active material is lithium cobalt oxide (LCO).

[0092] The amount of lithium cobalt oxide (LCO) added to the raw materials for preparing the positive electrode slurry layer is 95 wt %.

[0093] The positive electrode lithium supplement is lithium-rich ferrite (LFO).

[0094] The amount of lithium-rich lithium ferrite (LFO) added to the raw materials for preparing the positive electrode slurry layer is 1.5 wt %.

[0095] The conductive agent is conductive carbon black.

[0096] The amount of conductive carbon black added to the raw materials for preparing the positive electrode slurry layer is 2 wt %.

[0097] The binder is polyvinylidene fluoride.

[0098] The amount of polyvinylidene fluoride added to the raw materials for preparing the positive electrode slurry layer is 1.5 wt %.

[0099] The solvent was N-methyl-2-pyrrolidone.

[0100] The positive electrode metal current collector is aluminum foil.

[0101] The positive electrode active material lithium cobalt oxide (LCO), the positive electrode lithium supplement agent lithium ferrite (LFO), conductive carbon black and the binder polyvinylidene fluoride are mixed and dispersed in N-methyl-2-pyrrolidone to obtain a positive electrode slurry. The positive electrode slurry is evenly coated on both sides of the aluminum foil, and after drying, rolling and vacuum drying, the aluminum tab is welded with an ultrasonic welder to obtain the positive electrode.

[0102] In the negative electrode:

[0103] The solid electrolyte is lithium aluminum titanium phosphate (LATP).

[0104] The amount of LATP added to the raw materials for preparing the solid electrolyte layer is 97 wt%.

[0105] The solid electrolyte layer binder is polyvinyl alcohol with an alcoholysis degree of 80%.

[0106] The amount of polyvinyl alcohol added to the solid electrolyte layer is 1.5 wt%.

[0107] The solid electrolyte layer further contains a conductive agent and a solvent. The conductive agent is conductive carbon black.

[0108] The amount of conductive carbon black added to the raw materials for preparing the solid electrolyte layer is 1.5 wt%.

[0109] The solvent was N-methyl-2-pyrrolidone.

[0110] The negative electrode metal current collector is copper foil.

[0111] The solid electrolyte LATP is mixed with polyvinyl alcohol and a conductive agent to obtain a uniform mixed slurry. The slurry is evenly coated on both sides of the copper foil. After drying, rolling and vacuum drying, the nickel tab is welded with an ultrasonic welder to obtain the negative electrode.

[0112] The preparation method of the negative electrode-free lithium-ion battery is as follows:

[0113] The separator is wound with the positive electrode and the negative electrode to obtain a bare battery cell, which is then injected with electrolyte and packaged to obtain a negative electrode-free lithium-ion battery.

[0114] The diaphragm is a conventional PE-based diaphragm.

[0115] The thickness of the separator was 7 μm.

[0116] The electrolyte is lithium hexafluorophosphate electrolyte.

[0117] Example 2

[0118] This embodiment prepares a negative electrode-free lithium-ion battery. The difference from Example 1 is that the solid electrolyte is lithium lanthanum zirconium oxide (LLZO).

[0119] Example 3

[0120] This embodiment prepares a negative electrode-free lithium ion battery, which differs from Example 1 in that the solid electrolyte is lithium lanthanum zirconium titanate (LLZTO).

[0121] Example 4

[0122] This embodiment prepares a negative electrode-free lithium-ion battery. The difference from Example 1 is that the solid electrolyte is lithium aluminum germanium phosphate (LAGP).

[0123] Example 5

[0124] This embodiment prepares a negative electrode-free lithium ion battery. The difference from Example 1 is that the negative electrode contains polyvinyl alcohol with an alcoholysis degree of 84%.

[0125] Example 6

[0126] In this comparative example, a negative electrode-free lithium-ion battery is prepared. The difference from Example 1 is that the binder of the solid electrolyte layer is polyvinylidene fluoride.

[0127] Example 7

[0128] This embodiment prepares a negative electrode-free lithium ion battery. The difference from Example 6 is that the amount of solid electrolyte LATP added to the negative electrode is 88 wt%.

[0129] Comparative Example 1

[0130] This comparative example prepares a negative electrode-free lithium ion battery, which differs from Example 1 in that the negative electrode does not have a solid electrolyte layer.

[0131] Comparative Example 2

[0132] In this comparative example, a negative electrode-free lithium-ion battery is prepared. The difference from Example 1 is that the positive electrode slurry layer does not contain a positive electrode lithium supplement.

[0133] Comparative Example 3

[0134] In this comparative example, a negative electrode-free lithium ion battery is prepared. The difference from Example 6 is that the amount of polyvinylidene fluoride, a binder of the solid electrolyte layer, added is 0.07 wt %.

[0135] Comparative Example 4

[0136] In this comparative example, a lithium-ion battery without a negative electrode is prepared. The difference from Example 1 is that the negative electrode contains polyvinyl alcohol with an alcoholysis degree of 95%.

[0137] Performance Testing

[0138] The cycle performance and first efficiency of the batteries prepared in the examples and comparative examples were tested.

[0139] Cycle test: Tested at room temperature 25℃: The divided battery is charged to 4.48V with 0.5C constant current and constant voltage (cut-off current is 0.01C), and then discharged to 3.0V with 0.5C constant current.

[0140] Cycle capacity retention (%) = (Nth cycle discharge capacity / 1st cycle discharge capacity) cycle discharge %.

[0141] Battery initial efficiency (%) = fractional discharge capacity / (fractional charge capacity + formation charge capacity) / formation charge capacity%.

[0142] The results are shown in Table 1.

[0143] Table 1

[0144] The results in Table 1 show that in the negative electrode-free lithium ion battery provided by the present invention, the addition of a lithium replenisher on the positive electrode side can effectively compensate for the consumption of lithium ions by the reaction of the solid electrolyte LATP on the negative electrode side at low voltage, thereby improving the first-cycle coulombic efficiency of the battery. The solid electrolyte on the surface of the negative electrode metal current collector can induce uniform deposition of lithium ions and reduce the formation of lithium dendrites. When the solid electrolyte on the negative electrode current collector is combined with the positive electrode lithium replenisher, the structure of the positive electrode material is more stable, and the two synergistically improve the long-cycle performance of the negative electrode-free battery.

[0145] When the solid electrolyte layer binder is polyvinyl alcohol, lithium ions can be deposited more evenly on the surface of the electrode, reducing lithium dendrites and further improving the stability and rate performance of the battery during the cycle.

[0146] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the spirit of the present invention.

Claims

1. A negative electrode-free lithium-ion battery, characterized in that: include: A positive electrode, comprising a positive electrode metal current collector and a positive electrode slurry layer disposed on the surface of the positive electrode metal current collector, wherein the positive electrode slurry layer contains a positive electrode lithium supplement; The negative electrode comprises a negative electrode metal current collector and a solid electrolyte layer arranged on the surface of the negative electrode metal current collector, wherein the solid electrolyte layer contains a solid electrolyte and a solid electrolyte layer binder.

2. The negative electrode-free lithium-ion battery according to claim 1, characterized in that: The positive electrode slurry layer further contains a positive electrode active material, a conductive agent, a positive electrode slurry layer binder and a solvent.

3. The negative electrode-free lithium-ion battery according to claim 2, characterized in that: The positive electrode active material includes at least one of lithium cobalt oxide, lithium manganese oxide and lithium iron phosphate.

4. The negative electrode-free lithium-ion battery according to claim 2, characterized in that: The positive electrode active material is added in an amount of 90 wt % to 97 wt % in the raw material for preparing the positive electrode slurry layer.

5. The negative electrode-free lithium-ion battery according to claim 1 or 2, characterized in that: The positive electrode lithium supplement includes at least one of Li5FeO4, Li2NiO2, Li2O, Li6CoO4 and Li2CuO2.

6. The negative electrode-free lithium-ion battery according to claim 1 or 2, characterized in that: The positive electrode lithium supplement is added in an amount of 0.1 wt % to 5 wt % in the raw materials for preparing the positive electrode slurry layer.

7. The negative electrode-free lithium-ion battery according to claim 1, characterized in that: The solid electrolyte includes lithium aluminum titanium phosphate, lithium lanthanum zirconium oxide, lithium lanthanum zirconium titanium oxide, lithium aluminum germanium phosphate, lithium lanthanum titanium oxide and Li 10 GeP2S 12 At least one of; and / or, the solid electrolyte is added in an amount of 80wt% to 99wt% in the raw materials for preparing the solid electrolyte layer.

8. The negative electrode-free lithium-ion battery according to claim 1, characterized in that: The solid electrolyte layer binder includes at least one of polyvinyl alcohol, polyvinylidene fluoride and polyethylene oxide; and / or, the addition amount of the solid electrolyte layer binder in the raw materials for preparing the solid electrolyte layer is 0.1wt% to 3wt%; and / or, the alcoholysis degree of the solid electrolyte layer binder is 75% to 85%.

9. The negative electrode-free lithium-ion battery according to claim 1, characterized in that: The solid electrolyte layer binder is polyvinyl alcohol.

10. A method for preparing a negative electrode-free lithium ion battery according to any one of claims 1 to 9, characterized in that: The process comprises winding the separator, the positive electrode and the negative electrode to obtain a bare battery core, injecting an electrolyte and then packaging to obtain the negative electrode-free lithium ion battery.

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