High-energy-density power type semi-solid-state battery

Abstract

The invention relates to the technical field of lithium batteries, in particular to a high-energy-density power type semi-solid-state battery. The invention provides a high-energy-density power type semi-solid-state battery. The high-energy-density power type semi-solid-state battery comprises a positive electrode, a negative electrode and electrolyte, the positive electrode comprises a positive electrode current collector and a positive electrode material coated on the surface of the positive electrode current collector; the positive electrode material comprises a positive electrode active substance, a first conductive agent, a binder and a solid electrolyte; the electrolyte comprises a lithium salt, a solvent and an additive, the mass ratio of the lithium salt to the solvent to the additive is (16-17): (70-80): (11-12); the negative electrode comprises a negative electrode current collector and a negative electrode material coated on the surface of the negative electrode current collector; the negative electrode material comprises a negative electrode active substance, a second conductive agent and a functional binder; the functional binder comprises polyacrylic acid and a derivative thereof. The high-energy-density power type semi-solid battery has the advantages of high energy density, high rate capability and long cycle life.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and particularly to a high-energy density power-type semi-solid battery. Background Art

[0002] As is well known, there are often contradictory points among the energy density, power performance, cycle life and high-temperature performance of lithium-ion batteries. For example, for nickel-cobalt-manganese ternary lithium-ion batteries, with the increase of nickel content or the upper limit voltage of the battery, the structural stability and thermal stability of the ternary cathode material will deteriorate significantly. Higher nickel content or higher upper limit voltage will lead to aggravated nickel-lithium mixing, lattice disorder in the ternary cathode material, and is prone to generate rock salt phase, oxygen release, cycle deterioration and gas production at high temperature, etc.; the addition of silicon material will increase the cycle expansion of the negative electrode sheet, and repeated high expansion will cause the SEI layer on the surface of the negative active material to rupture, resulting in the deterioration of the battery cycle performance and high-temperature performance; high electrode loading is beneficial to improving the energy density of the battery, but not conducive to the improvement of the battery power performance. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a high-energy density power-type semi-solid battery. The high-energy density power-type semi-solid battery of the present invention has the advantages of high energy density, high rate performance and long cycle life at the same time.

[0004] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0005] The present invention provides a high-energy density power-type semi-solid battery, including a positive electrode, a negative electrode and an electrolyte;

[0006] The positive electrode includes a positive electrode current collector and a positive electrode material coated on the surface of the positive electrode current collector; the positive electrode material includes a positive electrode active material, a first conductive agent, a binder and a solid electrolyte;

[0007] The electrolyte includes a lithium salt, a solvent and an additive; the mass ratio of the lithium salt, the solvent and the additive is (16 - 17):(70 - 80):(11 - 12);

[0008] The negative electrode includes a negative electrode current collector and a negative electrode material coated on the surface of the negative electrode current collector, and the negative electrode material includes a negative electrode active material, a second conductive agent and a functional binder;

[0009] The functional binder includes polyacrylic acid and its derivatives.

[0010] Preferably, the solid electrolyte includes one or more of perovskite-type solid electrolyte, GARNET-type solid electrolyte and NASICON-type solid electrolyte;

[0011] The binder includes polyvinylidene fluoride with a relative molecular weight ≥ 1.2 million;

[0012] The first conductive agent includes one or more of conductive carbon black, carbon nanotubes, and conductive graphene;

[0013] The positive electrode active material includes LiNi 1-x-y Co x Mn y O2, where 1 - x - y ≥ 0.89, and x ≠ 0, y ≠ 0;

[0014] The positive electrode current collector is an aluminum foil with a thickness of 9 - 15 μm.

[0015] Preferably, the mass ratio of the positive electrode active material, the first conductive agent, the binder, and the solid electrolyte is (95.5 - 98):(1 - 2):(1 - 1.5):(0 - 1.5), and the mass of the solid electrolyte is not 0.

[0016] Preferably, the double - sided surface loading of the positive electrode material on the surface of the positive electrode current collector ≥ 270 g / m 2 .

[0017] Preferably, the polyacrylic acid derivative preferably includes one or more of sodium polyacrylate, lithium polyacrylate, and lithium polyacrylate in - situ polymerized with carbon nanotubes;

[0018] The functional binder further includes one or more of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, and styrene - butadiene rubber.

[0019] Preferably, the functional binder includes a mixture of sodium carboxymethyl cellulose and polyacrylic acid, a mixture of styrene - butadiene rubber and polyacrylic acid, or a mixture of sodium carboxymethyl cellulose, styrene - butadiene rubber, and polyacrylic acid.

[0020] Preferably, the negative electrode active material includes artificial graphite and / or silicon - carbon composite material;

[0021] The second conductive agent includes one or more of conductive carbon black, conductive graphite, and carbon nanotubes.

[0022] Preferably, the mass ratio of the negative electrode active material, the second conductive agent, and the functional binder is (93 - 95):(1 - 1.8):(3 - 6).

[0023] Preferably, the double - sided surface loading of the negative electrode material on the surface of the negative electrode current collector ≥ 90 g / m 2 .

[0024] Preferably, the lithium salt includes one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, and lithium bis(trifluoromethylsulfonyl)imide;

[0025] The solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, and ethyl propionate;

[0026] The additive includes one or several of lithium difluorophosphate, lithium difluorooxalate borate, vinylene carbonate, fluoroethylene carbonate, ethylene sulfate, 1,3 - propylene sulfonic acid lactone, methylene methanedisulfonate, tris(trimethylsilyl) phosphate, tri - propynyl phosphate, ethylene sulfate, 1,3 - propane sulfonic acid lactone, and methyl maleic anhydride.

[0027] The present invention provides a high - energy - density power - type semi - solid battery, which includes a positive electrode, a negative electrode, and an electrolyte; the positive electrode includes a positive - electrode current collector and a positive - electrode material coated on the surface of the positive - electrode current collector; the positive - electrode material includes a positive - electrode active material, a first conductive agent, a binder, and a solid electrolyte; the electrolyte includes a lithium salt, a solvent, and an additive; the mass ratio of the lithium salt, the solvent, and the additive is (16 - 17):(70 - 80):(11 - 12); the negative electrode includes a negative - electrode current collector and a negative - electrode material coated on the surface of the negative - electrode current collector, and the negative - electrode material includes a negative - electrode active material, a second conductive agent, and a functional binder; the functional binder includes polyacrylic acid and its derivatives. In the present invention, adding a solid electrolyte to the positive electrode can provide a certain amount of lithium source at high temperature and high voltage, stabilize the NCM lattice structure, and at the same time cover the surface of the positive - electrode particles, which can reduce the side reaction between the positive - electrode active material and the electrolyte at high temperature. At the same time, due to the ion - conducting characteristics of the solid electrolyte itself, it can reduce the internal resistance of the battery and improve the rate performance of the battery; by controlling the ratio of the lithium salt, the solvent, and the additive in the electrolyte, the present invention can reduce the battery impedance of the high - energy - density power - type semi - solid battery, stabilize the positive and negative electrode interface films, thereby improving the rate performance and high - temperature performance; at the same time, the use of the solid electrolyte can also reduce the amount of electrolyte added to a certain extent, and is beneficial to the utilization of the specific capacity of the positive - electrode active material, thereby improving the energy density of the high - energy - density power - type semi - solid battery; by selecting the functional binder, the present invention can effectively improve the problem of negative - electrode swelling and enhance the battery cycle life. According to the records of the embodiments, the high - energy - density power - type semi - solid battery of the present invention has a capacity retention rate ≥ 97% under the discharge condition of 7C, and when the high - energy - density power - type semi - solid battery is fully charged (100% SOC) and stored at 85°C for 4h, the battery core has no gas swelling, the capacity retention ≥ 90%, and the capacity recovery rate ≥ 94%; the cycle life is ≥ 1200 cycles under the condition of 1C charging and 3C discharging at full SOC, and the cycle life is ≥ 900 cycles under the condition of 1C charging and 5C discharging at full SOC. Description of the Drawings

[0028] Figure 1 SEM image of the positive - electrode material on the surface of the positive electrode described in Example 1;

[0029] Figure 2 SEM image of the negative electrode material on the surface of the negative electrode described in Example 1;

[0030] Figure 3 EDS image of the negative electrode material on the surface of the negative electrode described in Example 1;

[0031] Figure 4 Rate performance curve of the high energy density power type semi-solid state battery described in Example 1;

[0032] Figure 5 High temperature storage performance of the high energy density power type semi-solid state battery described in Example 1;

[0033] Figure 6 Room temperature cycling performance of the high energy density power type semi-solid state battery described in Example 1. Detailed implementation mode

[0034] The present invention provides a high energy density power type semi-solid state battery, comprising a positive electrode, a negative electrode and an electrolyte;

[0035] The positive electrode includes a positive electrode current collector and a positive electrode material coated on the surface of the positive electrode current collector; the positive electrode material includes a positive electrode active material, a first conductive agent, a binder and a solid electrolyte;

[0036] The electrolyte includes a lithium salt, a solvent and an additive; the mass ratio of the lithium salt, the solvent and the additive is (16-17):(70-80):(11-12);

[0037] The negative electrode includes a negative electrode current collector and a negative electrode material coated on the surface of the negative electrode current collector, and the negative electrode material includes a negative electrode active material, a second conductive agent and a functional binder;

[0038] The functional binder includes polyacrylic acid and its derivatives.

[0039] In the present invention, unless otherwise specified, all preparation raw materials are commercially available products well-known to those skilled in the art.

[0040] In the present invention, the positive electrode includes a positive electrode current collector and a positive electrode material coated on the surface of the positive electrode current collector; the positive electrode material includes a positive electrode active material, a first conductive agent, a binder and a solid electrolyte.

[0041] In the present invention, the tap density of the positive electrode is preferably 3.3-3.5 g / cm 3 . In the examples of the present invention, the tap density of the positive electrode can be 3.4 g / cm 3 .

[0042] In the present invention, the thickness of the positive current collector is preferably 9 to 15 μm, more preferably 10 to 13 μm. In the present invention, the positive current collector is preferably aluminum foil. In an embodiment of the present invention, the positive current collector can be aluminum foil with a thickness of 12 μm.

[0043] In the present invention, the double-sided surface loading of the positive electrode material on the surface of the positive current collector is preferably ≥ 270 g / m 2 . In an embodiment of the present invention, the double-sided surface loading of the positive electrode material on the surface of the positive current collector can be 310 g / m 2 .

[0044] In the present invention, the positive active material preferably includes LiNi 1-x-y Co x Mn y O2, where 1 - x - y ≥ 0.89. In an embodiment of the present invention, in the positive active material, x = 0.057 and y = 0.043. In the present invention, the positive active material preferably includes polycrystalline and single crystal, and the mass ratio of the polycrystalline to the single crystal is preferably (7 - 8):(2 - 3), more preferably 7:3.

[0045] In the present invention, the first conductive agent preferably includes one or more of conductive carbon black, carbon nanotubes, and conductive graphene; the carbon nanotubes preferably include single-walled carbon nanotubes and / or multi-walled carbon nanotubes; more preferably, it includes two or more of conductive carbon black, carbon nanotubes, and conductive graphene, and most preferably includes conductive carbon black, multi-walled carbon nanotubes, and single-walled carbon nanotubes; the mass ratio of the conductive carbon black, multi-walled carbon nanotubes, and single-walled carbon nanotubes is preferably (66 - 67):32:(1 - 1.5). In an embodiment of the present invention, the first conductive agent includes conductive carbon black, multi-walled carbon nanotubes, and single-walled carbon nanotubes with a mass ratio of 67:32:1.

[0046] In the present invention, the binder preferably includes polyvinylidene fluoride with a relative molecular weight ≥ 1.2 million. In the present invention, the solid electrolyte preferably includes one or more of perovskite-type solid electrolytes, GARNET-type solid electrolytes, and NASICON-type solid electrolytes; the perovskite-type solid electrolyte preferably includes La 2 / 3-x Li 3x TiO3 and its derivatives (the value range of x is preferably 0 ≤ x ≤ 0.2) or Li 3 / 8 Sr 7 / 16 Ta 3 / 4 Zr 1 / 4 O3; the La 2 / 3-x Li 3x TiO3 is preferably La 0.56 Li 0.33TiO3; The GARNET-type solid electrolyte preferably includes Li 7-x La3Zr 2-x Ta x O 12 (LLZO, the value range of x is preferably 0 ≤ x ≤ 0.6) and its derivatives or Li3Zr2Si2PO 12 , where the value range of x is preferably 0 ≤ x ≤ 0.6; The Li 7-x La3Zr 2-x Ta x O 12 is preferably Li7La3Zr2O 12 ; The NASICON-type solid electrolyte preferably includes Li 1+x Al x Ti 2-x (PO4) (LATP, the value range of x is preferably 0 ≤ x ≤ 0.5) and its derivatives; The Li 1+x Al x Ti 2-x (PO4) is preferably Li 1.5 Al 0.5 Ti 1.5 (PO4)3; When the solid electrolyte is more than two of the above specific selections, the present invention has no special limitation on the ratio of the above specific substances, and they can be mixed in any ratio. In the embodiments of the present invention, the solid electrolyte can be Li 1.5 Al 0.5 Ti 1.5 (PO4)3 or Li7La3Zr2O 12 .

[0047] In the present invention, the mass ratio of the positive electrode active material, the first conductive agent, the binder and the solid electrolyte is preferably (95.5 - 98):(1 - 2):(1 - 1.5):(0 - 1.5), and the mass of the solid electrolyte is not 0, more preferably (96.5 - 97.5):(1.3 - 1.6):(1.2 - 1.3):(0.5 - 1.0). In the embodiments of the present invention, the mass ratio of the positive electrode active material, the first conductive agent, the binder and the solid electrolyte can be 96.8:1.5:1.2:0.5 or 95.8:1.5:1.2:1.5.

[0048] In the present invention, due to its own heteroionic characteristics, the solid electrolyte can improve the battery rate performance to a certain extent and is beneficial to the utilization of the specific capacity of the positive electrode active material. The purpose and function are to improve the battery rate performance, increase the battery energy density, and reduce the side reaction between the electrolyte and the positive electrode active material at high temperature.

[0049] In the present invention, the method for preparing the positive electrode preferably comprises the following steps:

[0050] Mix a positive electrode active material, a first conductive agent, a binder, a solid electrolyte, and a solvent to obtain a positive electrode paste;

[0051] Coat the positive electrode paste on the surface of the positive electrode current collector and dry it to obtain the positive electrode.

[0052] The present invention has no special limitation on the type and amount of the solvent, and those well-known to those skilled in the art can be used.

[0053] The present invention has no special limitation on the coating and drying processes, and those well-known to those skilled in the art can be used.

[0054] In the present invention, the electrolyte comprises a lithium salt, a solvent, and an additive; the mass ratio of the lithium salt, the solvent, and the additive is (16 - 17):(70 - 80):(11 - 12), preferably (16.5 - 17):(72 - 80):(11 - 11.5). In the embodiments of the present invention, the mass ratio of the lithium salt, the solvent, and the additive can be 17:72:11 or 16.5:80:11.5.

[0055] In the present invention, the lithium salt preferably comprises one or more of lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethylsulfonyl)imide (LiTFSI). When the lithium salt is two or more of the above specific selections, the present invention has no special limitation on the ratio of the above specific substances, and they can be mixed in any ratio. In the embodiments of the present invention, the lithium salt can be LiPF6 and LiFSI with a mass ratio of 14.5:2.

[0056] In the present invention, the solvent preferably comprises one or more of ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and ethyl propionate (EtPr). When the solvent is two or more of the above specific selections, the present invention has no special limitation on the ratio of the above specific substances, and they can be mixed in any ratio. In the embodiments of the present invention, the solvent can be PC, EMC, and DEC with a mass ratio of 20:69:11 or EC, PC, EMC, and DEC with a mass ratio of 8:10.5:44.5:8.

[0057] In the present invention, the additive preferably includes one or more of lithium difluorophosphate (LiPO2F2), lithium difluorooxalate borate (LiODFB), vinylene carbonate (VC), fluoroethylene carbonate (FEC), ethylene sulfate (ES), 1,3 - propanesultone (PST), methylene methanedisulfonate (MMDS), tris(trimethylsilyl) phosphate (TMSP), tri - propynyl phosphate (TAPP), 1,3 - propane sultone (DTD), 1,3 - propane sultone (PS), and maleic anhydride (MMA). When the additive is two or more of the above specific selections, the present invention does not have any special limitation on the ratio of the above specific substances, and they can be mixed in any ratio. In the embodiments of the present invention, the additive can be FEC, DTD, PS, LiPO2F2, TPP, and MMA with a mass ratio of 8:1.8:1:0.8:0.2:0.5 or FEC, VC, DTD, PS, PST, LiPO2F2, and TMSP with a mass ratio of 7:0.5:1.5:1:0.15:0.7:0.15

[0058] In the present invention, the ratio of the mass of the electrolyte to the capacity of the high - energy - density power - type semi - solid battery is preferably (1.5 - 2.5) g:1 A·h, more preferably (1.6 - 2.2) g:1 A·h, and most preferably (1.8 - 2) g:1 A·h. In the embodiments of the present invention, the ratio of the mass of the electrolyte to the capacity of the high - energy - density power - type semi - solid battery can be 1.8 g:1 A·h.

[0059] In the present invention, the negative electrode includes a negative electrode current collector and a negative electrode material coated on the surface of the negative electrode current collector. The negative electrode material includes a negative electrode active material, a second conductive agent, and a functional binder; the functional binder includes polyacrylic acid and its derivatives.

[0060] In the present invention, the mass ratio of the negative electrode active material, the second conductive agent, and the functional binder is preferably (93 - 95):(1 - 1.8):(3 - 6). In the embodiments of the present invention, the mass ratio of the negative electrode active material, the second conductive agent, and the functional binder can be 93.9:1.6:4.5.

[0061] In the present invention, the negative electrode active material preferably includes artificial graphite and / or silicon-carbon composite material; the silicon-carbon composite material is preferably a vapor deposition silicon-carbon composite material, and the mass ratio of silicon to carbon in the silicon-carbon composite material is preferably (40 to 50):(50 to 60), more preferably (42 to 48):(52 to 58); the negative electrode active material more preferably includes artificial graphite and vapor deposition silicon-carbon composite material (the mass ratio of silicon to carbon is 48:52) with a mass ratio of 77:23. In the examples of the present invention, the negative electrode active material can be artificial graphite and vapor deposition silicon-carbon composite material (the mass ratio of silicon to carbon in the vapor deposition silicon-carbon composite material is 48:52) with a mass ratio of 77:23.

[0062] In the present invention, the second conductive agent preferably includes one or more of conductive carbon black (SP), conductive graphite, and carbon nanotubes; the carbon nanotubes preferably include single-walled carbon nanotubes and / or multi-walled carbon nanotubes (SWCNT); when the second conductive agent is more than two of the above specific selections, the present invention has no special limitation on the ratio of the above specific substances, and they can be mixed in any ratio. In the examples of the present invention, the second conductive agent can be SP and SWCNT with a mass ratio of 1.5:0.1.

[0063] In the present invention, the polyacrylic acid derivative preferably includes one or more of sodium polyacrylate, lithium polyacrylate, and lithium polyacrylate in-situ polymerized with carbon nanotubes; the functional binder preferably further includes one or more of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, and styrene-butadiene rubber; the functional binder preferably includes a mixture of sodium carboxymethyl cellulose and polyacrylic acid, a mixture of styrene-butadiene rubber and polyacrylic acid, or a mixture of sodium carboxymethyl cellulose, styrene-butadiene rubber, and polyacrylic acid. When the functional binder is a mixture of sodium carboxymethyl cellulose and polyacrylic acid, the mass ratio of sodium carboxymethyl cellulose to polyacrylic acid is preferably (0.5 to 1):(3.5 to 4.0); when the functional binder is a mixture of styrene-butadiene rubber and polyacrylic acid, the mass ratio of styrene-butadiene rubber to polyacrylic acid is preferably (0.5 to 1):(3.5 to 4.0); when the functional binder is a mixture of sodium carboxymethyl cellulose, styrene-butadiene rubber, and polyacrylic acid, the mass ratio of sodium carboxymethyl cellulose, styrene-butadiene rubber, and polyacrylic acid is preferably 0.5:(0.5 to 1):(3 to 3.5). In the examples of the present invention, the functional binder can be a mixture of sodium carboxymethyl cellulose and sodium polyacrylate or lithium polyacrylate in-situ polymerized with carbon nanotubes with a mass ratio of 0.5:4.

[0064] In the present invention, the polyacrylic acid is composed of a large number of linear carboxylic acid groups. The carboxylic acid groups on the molecular chain form hydrogen bonds, with a certain degree of crosslinking, which improves the adhesion and can form a good interaction force with Si molecules. It can effectively alleviate the volume expansion of silicon during the cycling process, and at the same time maintain the adhesion between the active material and the current collector, so that the electrode structure remains complete. Compared with the traditional sodium carboxymethyl cellulose and styrene-butadiene rubber system, polyacrylic acid belongs to linear bonding, has a higher anchoring degree for the active material, and the internal cohesion of the electrode is stronger. Further, adding a small amount of sodium carboxymethyl cellulose to polyacrylic acid is more conducive to the dispersion of graphite itself, and adding a small amount of styrene-butadiene rubber is beneficial to improving the flexibility of the electrode and reducing the internal stress of the electrode.

[0065] In the present invention, the thickness of the negative electrode current collector is preferably 4.5 to 9 μm, more preferably 6 to 8 μm. In the present invention, the negative electrode current collector is preferably copper foil. In the examples of the present invention, the negative electrode current collector can be copper foil with a thickness of 6 μm.

[0066] In the present invention, the double-sided surface loading of the negative electrode material on the surface of the negative electrode current collector is preferably ≥90 g / m 2 In the examples of the present invention, the double-sided surface loading of the negative electrode material on the surface of the negative electrode current collector can be 117 g / m 2

[0067] In the present invention, the tap density of the negative electrode is preferably 1.35 to 1.65 g / cm 3 more preferably 1.45 to 1.6 g / cm 3 In the examples of the present invention, the tap density of the negative electrode can be 1.55 g / cm 3

[0068] In the present invention, the preparation method of the negative electrode preferably includes the following steps:

[0069] Mix the negative electrode active material, the second conductive agent, the functional binder and the solvent to obtain a negative electrode slurry;

[0070] Coat the negative electrode slurry on the surface of the positive electrode current collector and dry it to obtain the negative electrode.

[0071] The present invention does not have any special limitations on the type and amount of the solvent, and the types and amounts well-known to those skilled in the art can be used.

[0072] The present invention does not have any special limitations on the coating and drying processes, and the processes well-known to those skilled in the art can be used.

[0073] The present invention does not impose any special limitation on the preparation method of the high energy density power type semi-solid battery, and it can be carried out by using a process well-known to those skilled in the art.

[0074] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts fall within the protection scope of the present invention.

[0075] Example 1

[0076] Positive electrode: The positive electrode current collector is an aluminum foil with a thickness of 12 μm;

[0077] Positive electrode material: It includes 96.8 parts by weight of positive electrode active material (LiNi 1-x-y Co x Mn y O2, x = 0.057, y = 0.043; wherein, the positive electrode active material includes polycrystalline and single crystal; the mass ratio of polycrystalline to single crystal is 7:3); 1.5 parts by weight of conductive agent (conductive carbon black, multi-walled carbon nanotubes and single-walled carbon nanotubes with a mass ratio of 67:32:1); 1.2 parts by weight of binder (PVDF with a relative molecular weight of 1.2 million) and 0.5 parts by weight of solid electrolyte (the specific type is Li 1.5 Al 0.5 Ti 1.5 (PO4)3);

[0078] The double-sided surface loading of the positive electrode material on the surface of the positive electrode current collector is 310 g / m 2 , and the compaction density of the positive electrode is 3.4 g / cm 3 ;

[0079] Preparation of the positive electrode: Mix the above-mentioned positive electrode active material, conductive agent, binder, solid electrolyte and solvent (the type of the solvent is N-methylpyrrolidone, and the mass ratio of the positive electrode active material to the mass of the solvent is 70:30) to obtain a positive electrode slurry;

[0080] Coat the positive electrode slurry on the surface of the positive electrode current collector, and dry it to obtain the positive electrode;

[0081] Negative electrode: The negative electrode current collector is a copper foil with a thickness of 6 μm;

[0082] Negative electrode material: It includes 93.9 parts by weight of negative electrode active material (specifically artificial graphite and vapor deposition silicon-carbon composite material with a mass ratio of 77:23, and the mass ratio of silicon to carbon in the vapor deposition silicon-carbon composite material is 48:52), 1.6 parts by weight of conductive agent (the types are SP and SWCNT with a mass ratio of 1.5:0.1), and 4.5 parts by weight of functional binder (sodium carboxymethyl cellulose and lithium polyacrylate with a mass ratio of 0.5:4);

[0083] The double-sided surface loading of the negative electrode material on the surface of the negative electrode current collector is 117 g / m 2 , and the tap density of the negative electrode is 1.55 g / cm 3 ;

[0084] Preparation of the negative electrode: Mix the above-mentioned negative electrode active material, conductive agent and binder to obtain a negative electrode slurry;

[0085] Coat the negative electrode slurry on the surface of the negative electrode current collector and dry it to obtain the negative electrode;

[0086] Electrolyte: A lithium salt, a solvent and an additive with a mass ratio of 17:72:11. The lithium salt is LiPF6 and LiFSI with a mass ratio of 14.5:2, the solvent is PC, EMC and DEC with a mass ratio of 20:69:11, and the additive is FEC, VC, DTD, PS, PST, LiPO2F2 and TMSP with a mass ratio of 7:0.5:1.5:1:0.15:0.7:0.15; the mass of the electrolyte is in a ratio of 1.8 g:1 A·h to the capacity of the high energy density power type semi-solid battery;

[0087] Assemble the positive electrode, negative electrode and electrolyte according to the conventional method to obtain a high energy density power type semi-solid battery;

[0088] Figure 1 is the SEM image of the positive electrode material on the surface of the positive electrode, and it can be seen from Figure 1 that the substances on the surface of the positive electrode are evenly dispersed;

[0089] Figure 2 is the SEM image of the negative electrode material on the surface of the negative electrode; Figure 3 is the EDS image of the negative electrode material on the surface of the negative electrode. It can be seen from Figures 2-3 that the negative electrode active material in the negative electrode material on the surface of the negative electrode is evenly dispersed, and the particles of the negative electrode active material are smooth and without cracks, indicating that the binder used can well bond the negative electrode active material;

[0090] The high energy density power type semi-solid state battery has a single cell energy density of 314.9 Wh / kg at a discharge rate of 0.5C; the high energy density power type semi-solid state battery supports continuous discharge at 7C, with a normal discharge curve and no voltage drop phenomenon (such as Figure 4 shown); two parallel experiments were conducted on the high energy density power type semi-solid state battery, where Figure 5 are the test results of the two parallel experiments of the high energy density power type semi-solid state battery, as Figure 5 shown, it performed well during high temperature storage at 85°C for 4h, without bulging or swelling, with a capacity retention rate of 94.92% (average value of the above two parallel experiments) and a capacity recovery rate of 97.77% (average value of the above two parallel experiments); the cycle life at 1C charge and 3C discharge conditions (1C / 3C) is 1470 cycles with a capacity retention rate of 80.06%, and the room temperature cycle life at 1C charge and 5C discharge conditions (1C / 5C) is 900 cycles with a capacity retention rate of 85.96% (as Figure 6 shown).

[0091] Example 2

[0092] Referring to Example 1, the difference is that the functional binder in the negative electrode includes sodium carboxymethyl cellulose and sodium polyacrylate with a mass ratio of 0.5:4;

[0093] The positive electrode, negative electrode and electrolyte were assembled according to the conventional method to obtain a high energy density power type semi-solid state battery;

[0094] The high energy density power type semi-solid state battery has a single cell energy density of 314 Wh / kg at a discharge rate of 0.5C; it supports continuous discharge at 7C, with a normal discharge curve and no voltage drop phenomenon; it performed well during high temperature storage at 85°C for 4h, the cell had no bulging or swelling, with a capacity retention rate of 96.07% and a capacity recovery rate of 98.27%; the room temperature cycle life at 1C charge and 3C discharge conditions is 1391 cycles with a capacity retention rate of 80.01%, and the room temperature cycle life at 1C charge and 5C discharge conditions is 900 cycles with a capacity retention rate of 84.65%.

[0095] Example 3

[0096] Referring to Example 1, the difference is that the functional binder is carbon nanotube in-situ polymerized lithium polyacrylate;

[0097] The positive electrode, negative electrode and electrolyte were assembled according to the conventional method to obtain a high energy density power type semi-solid state battery;

[0098] The high energy density power type semi-solid state battery has a single cell energy density of 314.3 Wh / kg at a discharge rate of 0.5C; it supports continuous discharge at 7C, with a normal discharge curve and no voltage drop; it performs well during 4-hour high temperature storage at 85°C. The cell has no bulging or swelling, with a capacity retention rate of 95.87% and a capacity recovery rate of 97.87%; at room temperature, the cycle life under the conditions of 1C charging and 3C discharging is 1250 cycles with a capacity retention of 80.05%, and under the conditions of 1C charging and 5C discharging, the cycle life at room temperature is 900 cycles with a capacity retention of 80.38%.

[0099] Example 4

[0100] Referring to Example 1, the difference is that the electrolyte is a lithium salt, a solvent, and an additive with a mass ratio of 16.5:80:11.5; the solvent in the electrolyte is EC, PC, EMC, and DEC with a mass ratio of 8:10.5:44.5:8, and the additive in the electrolyte is FEC, DTD, PS, LiPO2F2, TPP, and MMA with a mass ratio of 8:1.8:1:0.8:0.2:0.5;

[0101] The positive electrode, negative electrode, and electrolyte are assembled according to the conventional method to obtain a high energy density power type semi-solid state battery;

[0102] The high energy density power type semi-solid state battery has a single cell energy density of 314.5 Wh / kg at a discharge rate of 0.5C; it supports continuous discharge at 7C, with a normal discharge curve and no voltage drop; it performs well during 4-hour high temperature storage at 85°C. The cell has no bulging or swelling, with a capacity retention rate of 91.03% and a capacity recovery rate of 94.55%; at room temperature, the cycle life under the conditions of 1C charging and 3C discharging is 1320 cycles with a capacity retention of 80.04%, and under the conditions of 1C charging and 5C discharging, the cycle life at room temperature is 900 cycles with a capacity retention of 82.45%.

[0103] Example 5

[0104] Referring to Example 1, the difference is that the positive active material in the positive electrode material is 96.3 parts by weight, and the solid electrolyte is 1 part by weight;

[0105] The positive electrode, negative electrode, and electrolyte are assembled according to the conventional method to obtain a high energy density power type semi-solid state battery;

[0106] The high-energy density power-type semi-solid state battery has a single-cell energy density of 315.3 Wh / kg at a discharge rate of 0.5C; it supports continuous discharge at 7C, with a normal discharge curve and no voltage drop; it performs well during high-temperature storage at 85°C for 4 hours. The battery cells do not bulge or swell, with a capacity retention rate of 95.77% and a capacity recovery rate of 98.20%; at room temperature, the cycle life is 1650 cycles with 80% capacity retention under the conditions of 1C charging and 3C discharging, and the cycle life is 900 cycles with 86.3% capacity retention under the conditions of 1C charging and 5C discharging.

[0107] Example 6

[0108] Referring to Reference Example 1, the difference is that: in the positive electrode material, the positive electrode active material is 95.8 parts by weight and the solid electrolyte is 1.5 parts by weight;

[0109] The positive electrode, negative electrode, and electrolyte are assembled according to the conventional method to obtain a high-energy density power-type semi-solid state battery;

[0110] The high-energy density power-type semi-solid state battery has a single-cell energy density of 313.1 Wh / kg at a discharge rate of 0.5C; it supports continuous discharge at 7C, with a normal discharge curve and no voltage drop; it performs well during high-temperature storage at 85°C for 4 hours. The battery cells do not bulge or swell, with a capacity retention rate of 95.79% and a capacity recovery rate of 98.19%; at room temperature, the cycle life is 1590 cycles with 80% capacity retention under the conditions of 1C charging and 3C discharging, and the cycle life is 900 cycles with 84.3% capacity retention under the conditions of 1C charging and 5C discharging.

[0111] Example 7

[0112] Referring to Reference Example 1, the difference is that: the specific type of the solid electrolyte in the positive electrode material is Li7La3Zr2O 12 ;

[0113] The positive electrode, negative electrode, and electrolyte are assembled according to the conventional method to obtain a high-energy density power-type semi-solid state battery;

[0114] The high-energy density power-type semi-solid state battery has a single-cell energy density of 314.6 Wh / kg at a discharge rate of 0.5C; it supports continuous discharge at 7C, with a normal discharge curve and no voltage drop; it performs well during high-temperature storage at 85°C for 4 hours. The battery cells do not bulge or swell, with a capacity retention rate of 94.85% and a capacity recovery rate of 97.82%; at room temperature, the cycle life is 1403 cycles with 80% capacity retention under the conditions of 1C charging and 3C discharging, and the cycle life is 900 cycles with 82.3% capacity retention

[0115] Example 8

[0116] Referring to Example 1, the difference is that the functional binder in the negative electrode is styrene-butadiene rubber and lithium polyacrylate with a mass ratio of 0.5:4;

[0117] The positive electrode, negative electrode and electrolyte are assembled according to the conventional method to obtain a high energy density power type semi-solid battery;

[0118] The energy density of the single cell of the high energy density power type semi-solid battery is 314.8 Wh / kg at a discharge rate of 0.5C; it supports continuous discharge at 7C, the discharge curve is normal, and there is no voltage drop phenomenon; it performs well after 4h of high temperature storage at 85°C. The battery cell has no bulging or swelling, the capacity retention rate is 96.00%, and the capacity recovery rate is 98.27%; the room temperature cycle life under the conditions of 1C charging and 3C discharging is 1352 cycles with a capacity retention of 80.07%, and the room temperature cycle life under the conditions of 1C charging and 5C discharging is 900 cycles with a capacity retention of 81.36%.

[0119] Comparative Example 1

[0120] Referring to Example 1, the difference is that the positive electrode active material is 97.3 parts by weight and does not contain a solid electrolyte;

[0121] The assembly method is the same as that of Example 1 to obtain a semi-solid battery.

[0122] Comparative Example 2

[0123] Referring to Example 1, the difference is that the binder in the negative electrode material is sodium carboxymethyl cellulose and styrene-butadiene rubber with a mass ratio of 1.5:3;

[0124] The assembly method is the same as that of Example 1 to obtain a semi-solid battery.

[0125] Comparative Example 3

[0126] Referring to Example 1, the difference is that the electrolyte: a lithium salt, a solvent and an additive with a mass ratio of 16:69.4:14.6. The lithium salt is LiPF6 and LiFSI with a mass ratio of 10:6, the solvent is EC, PC, EMC and DEC with a mass ratio of 8.5:17.5:61.5:12.5, and the additive is FEC, VC, DTD, PST, LiPO2F2 and TMSP with a mass ratio of 12:0.3:1:0.3:0.8:0.3;

[0127] The assembly method is the same as that of Example 1 to obtain a semi-solid battery.

[0128] Table 1 Effect data of the high temperature resistance performance of the semi-solid batteries described in Comparative Examples 1-2

[0129]

[0130] As can be seen from the effect data in Table 1 and Example 1, compared with Example 1, the high-temperature resistance performance (capacity retention rate and recovery rate during high-temperature storage at 85°C for 4 h) and rate performance (1C / 3C and 1C / 5C) of Comparative Example 1 are worse than those of Example 1, proving that adding a solid electrolyte to the positive electrode material can improve the high-temperature resistance performance and rate performance of the above semi-solid battery;

[0131] Compared with Example 1, the cycle performance of Comparative Example 2 is significantly worse than that of Example 1, proving that adding the functional binder described in the present invention to the negative electrode can significantly improve the cycle life of the above semi-solid battery;

[0132] Compared with Example 1, the high-temperature resistance performance (capacity retention rate and recovery rate during high-temperature storage at 85°C for 4 h) and rate performance (1C / 3C and 1C / 5C) of Comparative Example 3 are worse than those of Example 1, proving that by controlling the ratio relationship of lithium salt, solvent and additive in the electrolyte, the high-temperature resistance performance and rate performance of the above semi-solid battery can be improved.

[0133] The above is only the preferred embodiment of the present invention, and it does not impose any form of limitation on the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A high energy density power type semi-solid state battery, characterized in that, It includes a positive electrode, a negative electrode and an electrolyte; The positive electrode includes a positive electrode current collector and a positive electrode material coated on the surface of the positive electrode current collector; the positive electrode material includes a positive electrode active material, a first conductive agent, a binder and a solid electrolyte; The electrolyte includes a lithium salt, a solvent and an additive; the mass ratio of the lithium salt, the solvent and the additive is (16 - 17):(70 - 80):(11 - 12); The negative electrode includes a negative electrode current collector and a negative electrode material coated on the surface of the negative electrode current collector, and the negative electrode material includes a negative electrode active material, a second conductive agent and a functional binder; The functional binder includes polyacrylic acid and its derivatives.

2. The high-energy density power-type semi-solid battery according to claim 1, wherein The solid electrolyte includes one or more of perovskite-type solid electrolytes, GARNET-type solid electrolytes and NASICON-type solid electrolytes; The binder includes polyvinylidene fluoride with a relative molecular weight ≥ 1.2 million; The first conductive agent includes one or more of conductive carbon black, carbon nanotubes and conductive graphene; The positive electrode active material includes LiNi 1-x-y Co x Mn y O2, where 1 - x - y ≥ 0.89, and x ≠ 0, y ≠ 0; The positive electrode current collector is an aluminum foil with a thickness of 9 - 15 μm.

3. The high-energy density power-type semi-solid state battery according to claim 1 or 2, characterized in that The mass ratio of the positive electrode active material, the first conductive agent, the binder and the solid electrolyte is (95.5 - 98):(1 - 2):(1 - 1.5):(0 - 1.5), and the mass of the solid electrolyte is not 0.

4. The high-energy density power-type semi-solid battery according to claim 3, wherein The double-sided surface loading of the positive electrode material on the surface of the positive electrode current collector ≥ 270 g / m 2 .

5. The high-energy density power-type semi-solid state battery according to claim 1, wherein The polyacrylic acid derivative preferably includes one or more of sodium polyacrylate, lithium polyacrylate and lithium polyacrylate in-situ polymerized with carbon nanotubes; The functional binder further includes one or more of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose and styrene-butadiene rubber.

6. The high-energy density power-type semi-solid state battery according to claim 5, wherein The functional binder includes a mixture of sodium carboxymethyl cellulose and polyacrylic acid, a mixture of styrene-butadiene rubber and polyacrylic acid, or a mixture of sodium carboxymethyl cellulose, styrene-butadiene rubber and polyacrylic acid.

7. The high-energy density power-type semi-solid state battery according to claim 1, 5 or 6, characterized in that, The negative electrode active material includes artificial graphite and / or silicon-carbon composite materials; The second conductive agent includes one or more of conductive carbon black, conductive graphite and carbon nanotubes.

8. The high-energy density power-type semi-solid battery according to claim 7, characterized in that The mass ratio of the negative electrode active material, the second conductive agent and the functional binder is (93 - 95):(1 - 1.8):(3 - 6).

9. The high-energy density power-type semi-solid state battery according to claim 8, wherein The double-sided surface loading of the negative electrode material on the surface of the negative electrode current collector ≥ 90 g / m 2 .

10. The high-energy density power-type semi-solid state battery according to claim 1, wherein The lithium salt includes one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethylsulfonyl)imide; The solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate and ethyl propionate; The additive includes one or more of lithium difluorophosphate, lithium difluoro(oxalato)borate, vinylene carbonate, fluoroethylene carbonate, ethylene sulfate, 1,3-propane sultone, methanedisulfonic acid methyl ester, tris(trimethylsilyl) phosphate, tripropargyl phosphate, ethylene sulfate, 1,3-propane sultone and methyl maleic anhydride.

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