A battery pole for a solid-state battery, a method for manufacturing the same, and a solid-state battery

Abstract

The application belongs to the technical field of batteries, and particularly relates to a battery pole piece for a solid-state battery, a preparation method thereof and the solid-state battery. Compared with the prior art, the application can prevent the increase of interface impedance and the decrease of ionic conductivity caused by the reaction between the active material and the solid-state electrolyte by arranging a coating layer on the surface of the active material to block electrons, and the one-dimensional carbon material positioned and coated on the surface of the active material keeps a rigid and stretched state, which can ensure that the electron transmission network between the core particles is not affected, so that the battery pole piece has an efficient ion and electron conduction network, and the rate performance and cycle performance of the solid-state battery are improved.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, and particularly relates to a battery electrode for solid-state batteries, its preparation method, and solid-state batteries. Background Technology

[0002] Based on the mass percentage of liquid electrolyte in the battery, lithium batteries can be classified into liquid batteries, semi-solid batteries, quasi-solid batteries, and all-solid batteries. Among them, semi-solid, quasi-solid, and all-solid batteries are collectively referred to as solid-state batteries. Solid-state batteries follow the same charge and discharge principles as liquid batteries, but replace the liquid electrolyte and separator in liquid batteries with a solid electrolyte, eliminating the safety hazards of flammability and leakage. At the same time, they significantly improve battery energy density, making them a key research direction for academia and industry.

[0003] As batteries transition from liquid to all-solid state, a key challenge arises: ion transport at the solid-solid interface. In particular, sulfide solid electrolytes have a narrow electrochemical window and undergo oxidation at the cathode, producing ions with very low conductivity, thus hindering ion transport. Furthermore, sulfide solid electrolytes themselves have low electronic conductivity (10⁻⁶ Ω·cm). -9 Furthermore, the electronic conductivity of the product after oxidation is even lower (10). -30 Therefore, its oxidation site is limited to the surface in contact with the positive electrode or conductive carbon.

[0004] In addition, in existing solid-state batteries, carbon materials are mixed with positive / negative electrode active materials and solid electrolytes to prepare positive / negative electrodes. This results in the carbon materials being uniformly mixed between the active materials, between the solid electrolytes, and between the two. When conductive carbon is mixed between the active materials, it can better conduct electrons, which is beneficial to rate performance. When conductive carbon is mixed between the solid electrolytes, it will lead to an increase in the interfacial impedance between the electrolytes and block the ion pathway. When conductive carbon is mixed between the active materials and the solid electrolyte, it will block the ion pathway from the active materials to the solid electrolyte, affecting the rate performance of the battery. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a battery electrode with high rate performance for solid-state batteries, a method for preparing the electrode, and a solid-state battery.

[0006] The present invention provides a battery electrode for a solid-state battery, comprising a first material and a first solid electrolyte;

[0007] The first material includes a core and a coating layer disposed on the surface of the core; the core is an active material; the coating layer includes a conductive agent and a second solid electrolyte; the conductive agent includes a one-dimensional carbon material, and at least one end of the one-dimensional carbon material extends out of the surface of the coating layer.

[0008] The first solid electrolyte includes a sulfide solid electrolyte;

[0009] The second solid electrolyte includes a polymer solid electrolyte.

[0010] Preferably, the average size of the one-dimensional carbon material extending out of the coating layer is 1~15 μm.

[0011] Preferably, the diameter of the core is 0.2~20 μm;

[0012] And / or, the shortest distance between adjacent coating layers of the first material is 0.5~10μm;

[0013] And / or, the thickness of the coating layer is 50 nm to 1 μm.

[0014] Preferably, the average size of the one-dimensional carbon material extending out of the coating layer is 1 to 10 times the shortest distance between the coating layers of adjacent first materials;

[0015] The diameter of the one-dimensional carbon material is 1~400 nm;

[0016] And / or, the length of the one-dimensional carbon material is 3~30 μm.

[0017] Preferably, the mass ratio of the first material to the first solid electrolyte is (80~90):(10~20).

[0018] Preferably, the coating layer includes a first coating layer and a second coating layer; the first coating layer is disposed between the core and the second coating layer; the first coating layer includes a first binder and the conductive agent; the second coating layer includes a second solid electrolyte; and the one-dimensional carbon material extends out of the second coating layer.

[0019] Preferably, the mass content of the conductive agent in the first coating layer is 10% to 95%.

[0020] Preferably, the one-dimensional carbon material is selected from carbon fibers and / or carbon nanotubes.

[0021] Preferably, the second solid electrolyte comprises a polymer and a lithium salt; or comprises a polymer, a lithium salt, and a filler.

[0022] The lithium salt has a mass of 1% to 300% of the polymer mass;

[0023] The mass of the filler is 1% to 30% of the polymer mass.

[0024] Preferably, the active material is a positive electrode active material;

[0025] The polymer is selected from one or more of polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, polyethylene glycol, polyethylene glycol methacrylate, polysiloxane, polyacrylonitrile, polycyanoacrylate and polyphosphazene;

[0026] The lithium salt is selected from one or more of lithium bis(trifluorosulfonyl)imide, lithium hexafluorophosphate, lithium bis(oxalato)borate, lithium perchlorate, lithium bis(fluorosulfonyl)imide, lithium hexafluoroarsenate, and lithium tetrafluoroborate.

[0027] The filler is selected from one or more of lithium aluminum titanium phosphate, lithium lanthanum zirconium oxide, lithium lanthanum zirconium titanium oxide, lithium lanthanum titanium oxide, silicon dioxide, and aluminum oxide;

[0028] The lithium salt accounts for 80% to 100% of the polymer mass.

[0029] The mass of the filler is 0% to 20% of the polymer mass.

[0030] Preferably, the positive electrode active material is selected from one or more of lithium iron phosphate, lithium cobalt oxide, lithium nickel manganese oxide, lithium manganese iron phosphate, lithium manganese oxide, and lithium nickel cobalt manganese oxide;

[0031] The diameter of the core is 0.5~20 μm;

[0032] The diameter of the one-dimensional carbon material is 10~200 nm.

[0033] Preferably, the mass ratio of the core to the second solid electrolyte is 90:10 to 97:3.

[0034] Preferably, the active material is a negative electrode active material;

[0035] The polymer is selected from one or more of polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, polyethylene glycol, polysiloxane, polyacrylonitrile, and polyphosphazene.

[0036] The lithium salt is selected from one or more of lithium bis(trifluorosulfonyl)imide, lithium hexafluorophosphate, lithium bis(oxalato)borate, lithium perchlorate, lithium bis(fluorosulfonyl)imide, lithium hexafluoroarsenate, and lithium tetrafluoroborate.

[0037] The filler is selected from one or more of lithium lanthanum zirconium oxide, lithium lanthanum zirconium titanium oxide, lithium lanthanum titanium oxide, silicon dioxide, and alumina;

[0038] The lithium salt comprises 20% to 100% of the polymer mass.

[0039] The mass of the filler is 0% to 20% of the polymer mass.

[0040] Preferably, the negative electrode active material is selected from one or more of silicon-based materials, graphite, and lithium titanate;

[0041] The diameter of the core is 0.2~20 μm;

[0042] The diameter of the one-dimensional carbon material is 5~150 nm.

[0043] Preferably, the mass ratio of the core to the second solid electrolyte is 85:15 to 90:10.

[0044] Preferably, the diameter of the core is 3~15 μm;

[0045] The length of the one-dimensional carbon material is 5~20 μm;

[0046] The average size of the one-dimensional carbon material extending out of the coating layer is 2~10 μm.

[0047] The present invention also provides a method for preparing the above-mentioned battery electrode, comprising the following steps:

[0048] S1) The active material, the second solid electrolyte, and the conductive agent are mixed in a solvent and then spray-dried to obtain the first material;

[0049] S2) The first material is mixed with the first solid electrolyte and pressed into shape to obtain a battery electrode for solid-state batteries.

[0050] Preferably, step S1) specifically comprises:

[0051] A1) The active material, the first binder and the conductive agent are dispersed and mixed in a solvent, and then spray-dried and aged by heating to obtain a primary coating material;

[0052] A2) The primary coating material is mixed with the second solid electrolyte in a solvent and then spray-dried to obtain the first material.

[0053] The present invention also provides a solid-state battery, including the battery electrode sheet described above.

[0054] Compared with the prior art, the present invention provides an electronic barrier by setting a coating layer on the surface of the active material, which can prevent the increase of interfacial impedance and the decrease of ionic conductivity caused by the reaction between the active material and the solid electrolyte. At the same time, the one-dimensional carbon material is positioned and coated on the surface of the active material to maintain a rigid and extended state, which can ensure that the electron transport network between the core particles is not affected, so that the battery electrode has a highly efficient ion and electron conduction network, thereby improving the rate performance and cycle performance of the solid battery. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the structure of the coating material provided by the present invention. Detailed Implementation

[0056] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0057] When using sulfides to make all-solid-state batteries, the interface between the solid electrolyte and the positive / negative electrode active materials is a particle-to-particle hard contact. On the one hand, the contact area is limited, and a certain pressure is required to maintain the contact state. On the other hand, the solid electrolyte at the interface is prone to side reactions to form a passivation layer, which further hinders ion transport.

[0058] To address the aforementioned problems, the present invention provides a battery electrode, comprising a first material and a first solid electrolyte; the first material comprises a core and a coating layer disposed on the surface of the core; the core is an active material; the coating layer comprises a conductive agent and a second solid electrolyte; the conductive agent comprises a one-dimensional carbon material, wherein at least one end of the one-dimensional carbon material extends beyond the surface of the coating layer;

[0059] The first solid electrolyte includes a sulfide solid electrolyte;

[0060] The second solid electrolyte includes a polymer solid electrolyte.

[0061] This application reduces side reactions between sulfide electrolytes and positive and negative electrode materials by coating the positive and negative electrode active materials with polymer electrolytes, avoiding problems such as increased interfacial impedance and decreased ionic conductivity caused by the formation of products. When using organic polymer solid electrolytes to coat the active materials, the lithium conductivity continuity of the coating layer extends the surface path for lithium transport in the active materials (indirectly increasing the interfacial contact area between the solid electrolyte and the active materials), which can improve ionic conductivity. At the same time, the conductive agent includes one-dimensional carbon materials, with at least one end of the one-dimensional carbon material extending out of the surface of the coating layer. By using one-dimensional carbon materials, which have a one-dimensional structure, they have higher strength and stiffness in a single direction. The one-dimensional structure is used to realize the electrical connection between the first materials, forming a conductive network, improving the overall conductivity of the electrode, and thus improving the rate performance and cycle performance of the battery.

[0062] See Figure 1 , Figure 1 A schematic diagram of the structure of the first material provided by the present invention.

[0063] In a specific embodiment of the present invention, the diameter of the core is preferably 0.2~20 μm. By controlling the core size within a suitable range, the ion transport path can be shortened and the rate performance improved. If the core size is too small, the coating structure is easily lost, and small particles easily fill the spaces between electrolytes, causing conductive connections between electrolytes. When conductive carbon is mixed between solid electrolytes, it will lead to an increase in interfacial impedance between electrolytes and obstruction of the ion pathway. However, if the core size is too large, it will easily increase the lithium-ion transport path and affect the lithium-ion insertion / extraction rate. Optionally, the size of the core is 0.2 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm or any two of the above values.

[0064] In one specific embodiment of the present invention, the diameter of the core is preferably 3-15 μm. Further controlling the diameter of the core within the range of 3-15 μm can further improve the rate capability and cycle performance of the battery.

[0065] The surface of the core is coated with a coating layer. By controlling the thickness of the coating layer, on the one hand, the core material is protected, reducing side reactions between the core material and the first solid electrolyte; on the other hand, one-dimensional carbon material extends from the edges, enabling electronic contact between the first materials and forming a conductive network. Therefore, in a specific embodiment provided by the present invention, the thickness of the coating layer is preferably 50 nm to 1 μm; optionally, the thickness of the coating layer is 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm, or any two of the above values.

[0066] According to the present invention, the coating layer includes a conductive agent, which can improve the electronic conductivity of the first material; the mass of the conductive agent is preferably 0.5% to 5% of the mass of the active material; optionally, the mass of the conductive agent is 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0% of the mass of the active material or a range between any two of the above values.

[0067] According to the present invention, the conductive agent comprises a one-dimensional carbon material; in a specific embodiment of the present invention, the one-dimensional carbon material is preferably carbon fiber and / or carbon nanotubes. In the present invention, at least one end of the one-dimensional carbon material extends beyond the surface of the coating layer, thereby forming an electron transport network; the length of the one-dimensional carbon material extending beyond the coating layer can be selected according to the distance between the first materials in the battery electrode. In a specific embodiment of the present invention, the average size of the one-dimensional carbon material extending beyond the coating layer is preferably 1~15 μm, more preferably 2~10 μm; optionally, the average size of the one-dimensional carbon material extending beyond the coating layer is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm or a range between any two of the above values. By controlling the length range of the one-dimensional carbon material extending beyond the coating layer, on the one hand, the one-dimensional carbon material can electrically connect different primary materials in the electrode to form a conductive network, thus avoiding affecting the rate performance of the battery; on the other hand, it can also prevent the one-dimensional carbon material from extending too far and falling between the electrolytes, causing an increase in interfacial impedance and affecting lithium-ion transport.

[0068] In one specific embodiment of the present invention, the average size of the one-dimensional carbon material extending out of the coating layer is preferably 2~10 μm.

[0069] In another specific embodiment provided by the present invention, the one-dimensional carbon material may also contact the core. The contacting part may be the end of the one-dimensional carbon material or a non-end part of the one-dimensional carbon material, without any special limitations.

[0070] The distance between the first materials directly affects the size of the one-dimensional carbon material and the density of the active material in the battery electrode, thus affecting the rate performance of the battery. In a specific embodiment of the present invention, the shortest distance between the coating layers of adjacent first materials, i.e., the shortest distance between adjacent first materials, is preferably 0.5~10 μm. Optionally, the shortest distance between the coating layers of adjacent first materials is 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or any two of the above values.

[0071] To ensure that the one-dimensional carbon material extends at least one end beyond the surface of the coating layer and contacts the one-dimensional carbon material in the adjacent first material to form a conductive network, in a specific embodiment of the present invention, the average size of the one-dimensional carbon material extending beyond the coating layer is preferably 1 to 10 times the shortest distance between the coating layers of the adjacent first materials. Optionally, the average size of the one-dimensional carbon material extending beyond the coating layer is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 times the shortest distance between the coating layers of the adjacent first materials, or any two of the above values. By controlling the average size of the carbon coating layer to be 1 to 10 times the shortest distance between the coating layers of the adjacent first materials, electrical connections between adjacent first materials are achieved using one-dimensional carbon material, while avoiding excessive extension and accumulation of the one-dimensional carbon material, which would affect ion transport.

[0072] In one specific embodiment of the present invention, the length of the one-dimensional carbon material is preferably 3-30 μm. By controlling the length of the one-dimensional carbon material within the range of 3-30 μm, the one-dimensional carbon material extends beyond the surface of the first material coating layer, achieving electrical contact between the first materials and forming a conductive network between different first materials. This improves the rate performance of the battery and also prevents the one-dimensional carbon material from agglomerating, thus hindering lithium-ion transport. Optionally, the length of the one-dimensional carbon material is 3 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, or any two of the above values.

[0073] In one specific embodiment of the present invention, the length of the one-dimensional carbon material is preferably 5 to 20 μm.

[0074] In a specific embodiment of the present invention, the diameter of the one-dimensional carbon material is preferably 1-400 nm. By controlling the diameter of the one-dimensional carbon material within the range of 1-400 nm, agglomeration is avoided, and easy shedding is prevented, thus avoiding the formation of a conductive network between the first materials and affecting the rate performance of the battery. Optionally, the diameter of the one-dimensional carbon material is 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, or any two of the above values.

[0075] In one specific embodiment of the present invention, the diameter of the one-dimensional carbon material is preferably 10~200 nm.

[0076] In this invention, the coating layer contains a second solid electrolyte; the second solid electrolyte includes a polymer solid electrolyte; by providing a polymer solid electrolyte in the coating layer, the problem of increased interfacial impedance caused by the reaction between the active material and the first solid electrolyte can be prevented; the polymer solid electrolyte preferably includes a polymer and a lithium salt, or includes a polymer, a lithium salt and a filler; by adding a filler, the conductivity of the coating layer can be increased; the filler is preferably an inorganic nanofiller.

[0077] In one specific embodiment of the present invention, the mass of the lithium salt is preferably 1% to 300% of the polymer mass, more preferably 10% to 200%, to ensure that the polymer's adhesiveness is maintained while improving the ionic conductivity; optionally, the mass of the lithium salt is 10%, 30%, 50%, 70%, 90%, 110%, 150%, 200% of the polymer mass or any two of the above values.

[0078] In one specific embodiment of the present invention, the mass of the filler is preferably 1% to 50% of the polymer mass, more preferably 3% to 20%, to ensure that the polymer's adhesion is maintained while reducing its crystallinity; optionally, the mass of the inorganic nanofiller is 3%, 5%, 7%, 9%, 11%, 13%, 15%, 17%, 20% of the polymer mass or any two of the above values.

[0079] In this invention, since the core is an active material, it can be either a positive or negative electrode active material. When the active material is a positive electrode active material, the electrode is a positive electrode; when the active material is a negative electrode active material, the electrode is a negative electrode. The negative electrode accepts lithium ions and stores energy during charging, and releases lithium ions and energy during discharging. The positive electrode, on the other hand, undergoes a chemical reaction with lithium ions during charging and discharging, thereby driving the battery's operation. The synergistic effect of these two components enables the solid-state battery to efficiently store and release energy. Due to the different active materials, the types of electrodes differ, and their functions also vary. Therefore, there are different requirements for the composition of the electrodes, especially the size of the one-dimensional carbon material and the content and type of the second solid electrolyte.

[0080] In one specific embodiment of the present invention, the core is a positive electrode active material; the diameter of the core is preferably 0.5~20 μm, more preferably 3~15 μm; optionally, the diameter of the core is 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm or any two of the above values.

[0081] In one specific embodiment of the present invention, the diameter of the core is selected from different ranges depending on the type of positive electrode active material; specifically, if the positive electrode active material is a ternary material, the diameter of the core is preferably 0.5~20 μm; if the positive electrode active material is lithium iron phosphate, the diameter of the core is preferably 0.5~5 μm; if the positive electrode active material is lithium cobalt oxide, the diameter of the core is preferably 5~20 μm.

[0082] In a specific embodiment of the present invention, the core is a positive electrode active material; the diameter of the one-dimensional carbon material is preferably 10~200 nm; optionally, the diameter of the one-dimensional carbon material is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm or any two of the above values.

[0083] In a specific embodiment of the present invention, the active material is a positive electrode active material, and the second solid electrolyte is preferably an antioxidant polymer solid electrolyte; more specifically, the polymer in the second solid electrolyte includes, but is not limited to, one or more of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyethylene oxide (PEO), polyethylene glycol (PEG), polyethylene glycol methacrylate (PEGMA), polysiloxane (PS), polyacrylonitrile (PAN), polycyanoacrylate, and polyphosphazene; the lithium salt in the second solid electrolyte includes, but is not limited to, […]. Limited to one or more of lithium trifluorosulfonylimide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium bis(oxalateborate) (LiBOB), lithium perchlorate (LiClO4), lithium bis(fluorosulfonylimide) (LiFSI), lithium hexafluoroarsenate (LiAsF), and lithium tetrafluoroborate (LiBF4); the filler in the second solid electrolyte includes, but is not limited to, one or more of lithium aluminum titanium phosphate (LATP), lithium lanthanum zirconium oxide (LLZO), lithium lanthanum zirconium titanium oxide (LLZTO), lithium lanthanum titanium oxide (LLTO), silicon dioxide (SiO2), and aluminum oxide (Al2O3).

[0084] In one specific embodiment of the invention, the weight-average molecular weight of the PVDF-HFP is preferably 10W to 100W; optionally, the weight-average molecular weight of the PVDF-HFP is 10 W, 20 W, 30 W, 40 W, 50 W, 60 W, 70 W, 80 W, 90 W, 100 W or any two of the above values.

[0085] In one specific embodiment of the invention, the molar content of HFP in the PVDF-HFP is preferably 10% to 30%; optionally, the molar content of HFP in the PVDF-HFP is 10%, 15%, 20%, 25%, 30%, or any two of the above values.

[0086] In one specific embodiment of the present invention, the weight-average molecular weight of the PEO is preferably 10W to 100W; optionally, the weight-average molecular weight of the PEO is 10 W, 20 W, 30 W, 40 W, 50 W, 60 W, 70 W, 80 W, 90 W, 100 W or any two of the above values.

[0087] In one specific embodiment of the present invention, the active material is a positive electrode active material; the mass of the lithium salt is preferably 80% to 100% of the polymer mass; optionally, the mass of the lithium salt is 80%, 85%, 90%, 95%, 100% of the polymer mass or a range between any two of the above values.

[0088] In one specific embodiment of the present invention, the active material is a positive electrode active material; the mass of the filler is preferably 0% to 20% of the polymer mass; optionally, the mass of the lithium salt is 0%, 5%, 10%, 15%, 20% of the polymer mass or a range between any two of the above values.

[0089] In one specific embodiment of the present invention, the active material is a positive electrode active material, and the mass ratio of the core to the second solid electrolyte is preferably 90:10 to 97:3; optionally, the mass ratio of the core to the second solid electrolyte is 90:10, 91:9, 92:8, 93:7, 94:6, 95:5, 96:4, 97:3 or any two of the above ratios.

[0090] In a specific embodiment of the present invention, the positive electrode active material is preferably one or more of lithium cobalt oxide (LCO), ternary materials, lithium manganese oxide (LiMn2O4), lithium iron phosphate (LFP), lithium nickel manganese oxide (LNMO), and lithium manganese iron phosphate (LMFP), more preferably one or more of lithium cobalt oxide (LCO), nickel cobalt manganese ternary materials (NCM), nickel cobalt aluminum ternary materials (NCA), lithium manganese oxide (LiMn2O4), lithium iron phosphate (LFP), lithium nickel manganese oxide (LNMO), and lithium manganese iron phosphate (LMFP).

[0091] In a specific embodiment provided by the present invention, the ternary material satisfies the general formula Li a1 Ni b1 Co c1 M1d1 M2 e1 O f1 R g1 Wherein, 0.75≤a1≤1.2, 0<b1<1, 0<c1<1, 0<d1<1, b1+c1+d1=1, 0≤e1≤0.2, 1≤f1≤2.5, 0≤g1≤1, f1+g1≤3; M1 can be Mn and / or Al; M2 can be one or more of B, Zr, Ti, Si, Mo, La, Ce, Te, Nb, Ta, Si, Al, W, Sr, V, Y, Mg, Co and Li; R includes, but is not limited to, at least one of N, F, S and Cl.

[0092] In one specific embodiment of the present invention, the positive electrode active material is a nickel-cobalt-manganese ternary material (NCM); the areal density of the positive electrode sheet is preferably 10~50 mg / cm³. 2 Optionally, the areal density of the positive electrode is 10 mg / cm³. 2 15 mg / cm 2 20 mg / cm 2 25 mg / cm 2 30 mg / cm 2 35 mg / cm 2 40 mg / cm 2 45 mg / cm 2 50 mg / cm 2 Or a range between any two of the above values; the compaction density of the positive electrode sheet is preferably 3.2~3.8 g / cm³. 3 Optionally, the compaction density of the positive electrode sheet is 3.2 g / cm³. 3 3.3 g / cm 3 3.4 g / cm 3 3.5 g / cm 3 3.6 g / cm 3 3.7g / cm 3 3.8 g / cm 3 Or the range between any two of the above values.

[0093] In one specific embodiment of this invention, lithium iron phosphate (LFP) is a positive electrode active material with an olivine-type crystal structure, possessing advantages such as low cost and high safety. The general chemical formula of lithium iron phosphate can be LiFe. 1-a2 M a2 PO b2 Q c2Where a2≤0.1, 3.85≤b2≤4, 0≤c2≤0.05, and the doping element M includes, but is not limited to, one or more of Mn, Ni, Co, Cr, Cu, Bi and S.

[0094] In one specific embodiment of the present invention, the positive electrode active material is lithium iron phosphate; the areal density of the positive electrode sheet is preferably 12~60 mg / cm³. 2 Optionally, the areal density of the positive electrode is 12 mg / cm³. 2 15 mg / cm 2 20 mg / cm 2 25 mg / cm 2 30 mg / cm 2 35 mg / cm 2 40 mg / cm 2 45 mg / cm 2 50 mg / cm 2 55 mg / cm 2 60 mg / cm 2 Or the range between any two of the above values; the compaction density of the positive electrode sheet is preferably 2.45~2.78 g / cm³. 3 Optionally, the compaction density of the positive electrode sheet is 2.45 g / cm³. 3 2.5 g / cm 3 2.58 g / cm 3 2.6 g / cm 3 2.7g / cm 3 2.75 g / cm 3 2.78 g / cm 3 Or the range between any two of the above values.

[0095] In one specific embodiment of the present invention, the positive electrode active material is lithium cobalt oxide; the areal density of the positive electrode sheet is preferably 14.4~72 mg / cm³. 2 Optionally, the areal density of the positive electrode is 14.4 mg / cm³. 2 15 mg / cm 2 20 mg / cm 2 25 mg / cm 2 30 mg / cm 2 35 mg / cm 2 40 mg / cm 2 45 mg / cm 2 50 mg / cm 2 55 mg / cm 260 mg / cm 2 65 mg / cm 2 70 mg / cm 2 72 mg / cm 2 Or a range between any two of the above values; the compaction density of the positive electrode sheet is preferably 3.8~4.2 g / cm³. 3 Optionally, the compaction density of the positive electrode sheet is 3.8 g / cm³. 3 3.9g / cm 3 4.0 g / cm 3 4.1 g / cm 3 4.2 g / cm 3 Or the range between any two of the above values.

[0096] In one specific embodiment of the present invention, the core is a negative electrode active material; the diameter of the core is preferably 0.2~20 μm, more preferably 3~15 μm; optionally, the diameter of the core is 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm or any two of the above values.

[0097] In one specific embodiment of the present invention, the core is a negative electrode active material; the diameter of the one-dimensional carbon material is preferably 5~150 nm.

[0098] In one specific embodiment of the present invention, the active material is a negative electrode active material; the mass ratio of the core to the second solid electrolyte is preferably 85:15 to 90:10; optionally, the mass ratio of the core to the second solid electrolyte is 85:15, 86:14, 87:13, 88:12, 89:11, 90:10 or any two of the above ratios.

[0099] In a specific embodiment of the present invention, the active material is a negative electrode active material, and the polymer in the second solid electrolyte includes, but is not limited to, one or more of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyethylene oxide (PEO), polyethylene glycol (PEG), polysiloxane (PS), polyacrylonitrile (PAN), and polyphosphazene; the lithium salt includes, but is not limited to, lithium bis(trifluorosulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium bis(oxalateborate)borate (LiBOB), lithium perchlorate (LiClO4), lithium bis(fluorosulfonyl)imide (LiFSI), lithium hexafluoroarsenate (LiAsF), and lithium tetrafluoroborate (LiBF4); the inorganic nanofiller includes, but is not limited to, lithium lanthanum zirconium oxide (LLZO), lithium lanthanum zirconium titanium oxide (LLZTO), lithium lanthanum titanium oxide (LLTO), silicon dioxide (SiO2), and aluminum oxide (Al2O3).

[0100] In one specific embodiment of the present invention, the active material is a negative electrode active material; the mass of the lithium salt is preferably 20% to 100% of the polymer mass; optionally, the mass of the lithium salt is 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% of the polymer mass or a range between any two of the above values.

[0101] In one specific embodiment of the present invention, the active material is a negative electrode active material; the mass of the filler is preferably 0% to 20% of the polymer mass; optionally, the mass of the lithium salt is 0%, 5%, 10%, 15%, 20% of the polymer mass or a range between any two of the above values.

[0102] In this invention, the negative electrode active material can be any negative electrode active material well known to those skilled in the art, and there are no special limitations. In a specific embodiment provided by this invention, the negative electrode active material is preferably one or more of silicon-based materials, graphite and lithium titanate; the silicon-based materials include, but are not limited to, one or more of silicon-oxygen materials, silicon-carbon materials, silicon alloys and elemental silicon.

[0103] In one specific embodiment of the present invention, the areal density of the negative electrode sheet is preferably 6~30 mg / cm³. 2 Optionally, the areal density of the negative electrode is 6 mg / cm³. 2 10 mg / cm 2 15 mg / cm 2 20 mg / cm 2 25 mg / cm 2 30 mg / cm 2 Or the range between any two of the above values.

[0104] In one specific embodiment of the present invention, the compaction density of the negative electrode sheet is preferably 1.2~1.8 g / cm³. 3 Optionally, the compaction density of the negative electrode sheet is 1.2 g / cm³. 3 1.3 g / cm 3 1.4 g / cm 3 1.45 g / cm 3 1.5g / cm 3 1.6 g / cm 3 1.7 g / cm 3 1.8 g / cm 3 Or the range between any two of the above values.

[0105] In another specific embodiment of the present invention, the coating layer includes a first coating layer and a second coating layer; the first coating layer is disposed between the core and the second coating layer; the first coating layer includes a first binder and a conductive agent; the second coating layer includes a second solid electrolyte; the one-dimensional carbon material is fixed in the coating layer by the first binder and extends out of the second coating layer. The coating layer ensures the electronic insulation strength of the coating layer surface. To avoid excessive coverage of the one-dimensional carbon material by the coating layer, it is preferable to first use the first coating layer to fix the one-dimensional carbon, maintaining its rigid extension state. Then, the second coating layer is used to prevent excessive burial of the one-dimensional carbon inside the coating layer, while ensuring good contact between the one-dimensional carbon and the core.

[0106] In a specific embodiment of the present invention, the mass of the conductive agent is preferably 10% to 95% of the mass of the first coating layer; optionally, the mass of the conductive agent is 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or any two of the above values, of the mass of the first coating layer; the first binder is an binder that undergoes cross-linking hardening upon heating and aging (and is no longer soluble in the solvent after aging), and is prone to cross-linking hardening upon heating and aging. The first adhesive loses its solubility by chemical reaction, thus ensuring that the first coating layer is not dissolved or damaged during the second coating. Specifically, the first adhesive is preferably a polymer containing unsaturated bonds that are easy to crosslink or certain specific groups that are easy to oxidize and crosslink. More specifically, it can be one or more of the following: polyvinylpyrrolidone (PVP), polycarboxylate superplasticizer (PCE), sodium carboxymethyl cellulose (CMC), polyacrylic acid (PAA), lithium-ionized polyacrylic acid (Li-PAA), polyvinyl alcohol (PVA), polystyrene-polybutadiene-polystyrene triblock copolymer (SBS), and styrene-butadiene rubber.

[0107] In one specific embodiment of the present invention, the weight-average molecular weight of the polyvinylpyrrolidone (PVP) is preferably 1 to 20 W; optionally, the weight-average molecular weight of the polyvinylpyrrolidone (PVP) is 1 W, 2 W, 3 W, 4 W, 5 W, 6 W, 7 W, 8 W, 9 W, 10 W, 11 W, 12 W, 13 W, 14 W, 15 W, 16 W, 17 W, 18 W, 19 W, 20 W, or any two of the above values.

[0108] In one specific embodiment of the present invention, the weight-average molecular weight of the polyacrylic acid (PAA) is preferably 10 to 100 W; optionally, the weight-average molecular weight of the polyacrylic acid (PAA) is 10 W, 20 W, 30 W, 40 W, 50 W, 60 W, 70 W, 80 W, 90 W, 100 W or any two of the above values.

[0109] According to the present invention, the battery electrode includes a first solid electrolyte; the preferred mass ratio of the first material to the first solid electrolyte is (57~90):(10~40); optionally, the mass ratio of the coating material to the first solid electrolyte is 57:40, 60:38, 65:35, 70:40, 75:25, 78:22, 80:20, 82:18, 84:16, 85:15, 86:14, 88:12, 90:10 or any two of the above ratios.

[0110] In a specific embodiment of the present invention, the first solid electrolyte is preferably a sulfide solid electrolyte; the sulfide solid electrolyte includes, but is not limited to, one or more of lithium phosphorus-sulfur-chloride, lithium germanium-phosphorus-sulfide, lithium phosphorus-sulfur-chloride derivatives and lithium germanium-phosphorus-sulfur derivatives.

[0111] In a specific embodiment provided by the present invention, the preferred structural formula of the lithium phosphorus sulfur chlorine is Li. 6- x1 PS 5-x1 Cl 1+x1 Where 0 ≤ x1 < 1.

[0112] In a specific embodiment provided by the present invention, the preferred structural formula of the lithium-germanium-phosphorus-sulfur compound is Li. 10+ x2 Ge 1-x2 P2S 12 ; 0 ≤ x² ≤ 1.

[0113] In a specific embodiment of the present invention, the lithium phosphorus sulfide chlorine derivative is preferably oxygen-doped and / or halogen-doped; the preferred structural formula of the oxygen-doped lithium phosphorus sulfide chlorine derivative is Li6PS.5-x3 O x3 Cl, where 0 < x3 < 1; the preferred structural formula of the halogen-doped lithium phosphorus sulfide chlorine derivative is Li6PS5M. 1-x M′ x4 , where 0 < x4 < 1, M and M′ are independently Cl, Br or I, and are not the same.

[0114] In a specific embodiment of the present invention, the lithium germanium phosphorus-sulfur derivative is preferably one or more of element-doped lithium germanium phosphorus-sulfur, element-substituted lithium germanium phosphorus-sulfur, oxygen-doped lithium germanium phosphorus-sulfur, and halogen-doped lithium germanium phosphorus-sulfur; the preferred structural formula of the element-doped lithium germanium phosphorus-sulfur is Li. 10+x5 Ge 1-x5 M″ x5 P2S 12 0≤x5<1, M″ is preferably one or more of La, Ce, Pr, Nd, Bi and Re; the structural formula of the element-substituted lithium germanium phosphorus sulfur is preferably Li 10 AP2S 12 A is preferably Sn and / or Si; the oxygen-doped lithium germanium phosphorus sulfur structure is preferably Li 9.54 Ge 1.74 P2S 11.7 O 0.3 The preferred structural formula for the halogen-doped lithium germanium phosphorus sulfur is Li. 9.6 GeP2S 11.4 A′ 0.6 A′ is preferably Br and / or Cl.

[0115] In a specific embodiment of the present invention, the sulfide solid electrolyte is preferably lithium phosphorus sulfur chloride; the preferred structural formula of the lithium phosphorus sulfur chloride is Li 6-x1 PS 5-x Cl 1+x1 x = 0 or 0.5; that is, the preferred structural formula of the lithium phosphorus sulfur chloride is Li6PS5Cl and / or Li 5.5 PS 5.4 Cl 1.5 .

[0116] In one specific embodiment of the present invention, the structural formula of the lithium germanium phosphorus sulfur is Li 10 GeP2S 12 .

[0117] In one specific embodiment provided by the present invention, the structural formula of the lithium germanium phosphorus sulfur derivative is Li 10.5 Ge 0.5 La 0.5 P2S 12 .

[0118] According to the present invention, the battery electrode includes an electrode active layer; the electrode active layer includes a first material and a first solid electrolyte; the mass of the first solid electrolyte is preferably 10% to 40% of the mass of the electrode active layer; optionally, the mass of the first solid electrolyte is 10%, 12%, 14%, 15%, 18%, 20%, 25%, 30%, 35%, 40% of the mass of the electrode active layer or a range between any two of the above values.

[0119] More preferably, the electrode active layer further includes a second binder; the mass of the second binder is preferably 0.5% to 3% of the mass of the electrode active layer; optionally, the mass of the second binder is 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3% of the mass of the electrode active layer or a range between any two of the above values.

[0120] In this invention, the second binder is selected according to the type of electrode active layer; the electrode active layer is a negative electrode active layer, and the second binder is preferably at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1 B, water-based acrylic resin (e.g., one or more of polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS, etc.), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and sodium carboxymethyl cellulose (CMC); the electrode active layer is a positive electrode active layer, and the second binder is preferably at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0121] In one specific embodiment of the present invention, the molecular weight of the polytetrafluoroethylene (PTFE) is preferably 1×10⁻⁶. 6 ~1×10 7 g / mol.

[0122] According to the present invention, the battery electrode preferably further includes a current collector; the electrode active layer is disposed on at least one surface of the current collector; the current collector can be any current collector well known to those skilled in the art, and there are no special limitations. The present invention includes, but is not limited to, aluminum metal, aluminum alloy, carbon-coated aluminum foil, nickel-plated copper metal, copper alloy, copper foil or stainless steel foil.

[0123] This invention employs a coating layer on the surface of the active material to create an electron barrier, preventing the reaction between the active material and the solid electrolyte from causing a decrease in ionic conductivity. Simultaneously, the one-dimensional carbon material, rigidly positioned and coated on the surface of the active material, ensures that the electron transport network between the core particles remains unaffected. With electron transport guaranteed, the battery electrodes exhibit high ionic conductivity, thereby improving the rate performance and cycle life of the solid-state battery.

[0124] The present invention also provides a method for preparing the above-mentioned battery electrode, comprising the following steps: S1) mixing an active material, a conductive agent and a second solid electrolyte in a solvent, and spray drying to obtain a first material; S2) mixing the first material with a first solid electrolyte, pressing and molding to obtain a battery electrode for a solid-state battery.

[0125] In this invention, there are no special restrictions on the source of any raw materials; they can be commercially available. The active material, conductive agent, second solid electrolyte, and first solid electrolyte are all as described above and will not be repeated here.

[0126] The active material, conductive agent, and second solid electrolyte are mixed in a solvent and then spray-dried to obtain the first material. The solvent can be any solvent well known to those skilled in the art, including, but not limited to, one or more of N-methylpyrrolidone, N,N-dimethylformamide, acetonitrile, n-heptane, tetrahydrofuran, toluene, xylene, ethyl acetate, butyl butyrate, ethanol, and water.

[0127] Using a thick coating layer can ensure the electronic insulation strength of the coating layer surface, but if a thick coating is applied directly in one step, a large amount of one-dimensional carbon material will be covered by the coating layer. First, a thin coating layer is used to fix the one-dimensional carbon to the core, maintaining its rigid and extended state. Then, a second thick coating layer is applied, preventing excessive burial of the one-dimensional carbon within the coating layer and ensuring good contact between the one-dimensional carbon and the core. Therefore, in a specific embodiment provided by this invention, step S1) specifically includes: A1) dispersing and mixing the active material, the first binder, and the conductive agent in a solvent, followed by spray drying and heat aging to obtain a primary coating material; A2) mixing the primary coating material and the second solid electrolyte in a solvent, followed by spray drying to obtain the first material.

[0128] In one specific embodiment of the present invention, in order to disperse the one-dimensional carbon material, in addition to adding a first binder, a surfactant may also be added during dispersion. The surfactant is preferably one or more of sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS), hexadecyltrimethylammonium bromide (CTAB), and polyethylene glycol octylphenyl ether (Triton X-100).

[0129] In one specific embodiment of the present invention, the dispersion method includes one or more of ball milling, ultrasonic cavitation and high-pressure homogenization.

[0130] The first material is mixed with the first solid electrolyte and pressed to form a battery electrode. More specifically, a second binder is added during mixing. The amount and type of the second binder are the same as described above and will not be repeated here. The pressing is preferably a dry rolling process. More specifically, the battery electrode is pressed and bonded to the current collector to obtain the battery electrode.

[0131] The present invention also provides a solid-state battery, including the battery electrode sheet described above.

[0132] According to the present invention, the solid-state battery includes a positive electrode, a negative electrode, and an electrolyte membrane.

[0133] In one specific embodiment of the present invention, the positive electrode sheet is a battery electrode sheet in which the above-mentioned active material is the positive electrode active material.

[0134] In one specific embodiment of the present invention, the negative electrode sheet is a battery electrode sheet in which the above-mentioned active material is the negative electrode active material.

[0135] In one specific embodiment of the present invention, the electrolyte membrane comprises a sulfide solid electrolyte; the sulfide solid electrolyte is as described above and will not be repeated here.

[0136] In one specific embodiment of the present invention, the thickness of the electrolyte membrane is preferably 20-150 μm; optionally, the thickness of the electrolyte membrane is 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm or any two of the above values.

[0137] In one specific embodiment of the present invention, the electrolyte membrane preferably further includes a binder; the binder is preferably PTFE, used to prepare the electrolyte membrane by dry method; the mass of the binder is preferably 0.5% to 3% of the mass of the electrolyte membrane; optionally, the mass of the binder is 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3% of the mass of the electrolyte membrane or a range between any two of the above values.

[0138] In this invention, the solid-state battery can be prepared according to methods well known to those skilled in the art, without any special limitations. Specifically, it can be prepared by sequentially bonding the positive electrode, electrolyte membrane and negative electrode, encapsulating and then pressurizing to obtain the solid-state battery. Excessive pressure may cause the coating layers on the positive and negative electrodes to be squeezed out and damage the structure. Therefore, the pressure of the pressurization process can be 100~600 MPa.

[0139] To further illustrate the present invention, the following describes in detail the battery electrode, its preparation method, and the solid-state battery provided by the present invention with reference to embodiments.

[0140] All reagents used in the following examples are commercially available; the structural formula of NCM used in the examples and comparative examples is LiNi. 0.92 Co 0.04 Mn 0.04 O2; the structural formula of lithium iron phosphate is LiFePO4; the molecular weight of PTFE is 1×10 7 g / mol; the PVP used was PVP K30; the molecular weight of the PVDF-HFP used was approximately 20W, and the molar content of HFP in the PVDF-HFP was 20%; the molecular weight of the PAA used was approximately 20W; and the molecular weight of the PEO used was approximately 30W.

[0141] Examples 1 to 18

[0142] The types and sizes of the raw materials are shown in Tables 1 and 2.

[0143] 1. Preparation of secondary coated cathode material: Using ethanol as solvent, PVP and one-dimensional carbon material are dispersed by ultrasonication. Then, cathode material (as core) is added and mixed evenly (the mass ratio of cathode material, PVP and one-dimensional carbon material is 95:1.5:3.5). After spray drying at 130℃, it is aged by forced air heating at 120℃ for 10 h to make PVP no longer soluble in solvent after aging, thus obtaining primary coated cathode material.

[0144] Using ethyl acetate as a solvent, the above-mentioned primary coated cathode material and the second solid electrolyte were dispersed and mixed, and then spray-dried at 130°C to obtain the secondary coated cathode material;

[0145] 2. Positive electrode preparation: The secondary coated positive electrode material (82%) and the sulfide electrolyte (17%) are combined. 5.5 PS 4.5 Cl 1.5 The cathode material is NCM, and the areal density of the cathode sheet is 25 mg / cm³. The mixture is then rolled into sheets using a roller mill and adhered to aluminum foil to prepare a dry-process positive electrode sheet. 2 The compaction density of the positive electrode sheet is 3.58 g / cm³. 3The cathode material is lithium iron phosphate, and the areal density of the cathode sheet is 30 mg / cm³. 2 The compacted density is 2.58 g / cm³. 3 The cathode material is lithium cobalt oxide, and the areal density of the cathode sheet is 36 mg / cm³. 2 The compacted density is 4 g / cm³. 3 .

[0146] 3. Preparation of secondary coated negative electrode material: Water was used as a solvent to disperse PVP and one-dimensional carbon material by ultrasonication. Then, the negative electrode material was added and mixed evenly (the mass ratio of negative electrode material, PVP and one-dimensional carbon material was 95:1.5:3.5). After spray drying at 130℃, it was aged by forced air heating at 90℃ for 10 h to make PVP no longer soluble in the solvent after aging, thus obtaining the primary coated negative electrode material.

[0147] Using water as a solvent, the above-mentioned primary coated anode material and the second solid electrolyte are dispersed and mixed, and then spray-dried at 130°C to obtain the secondary coated anode material;

[0148] 4. Negative electrode preparation: The secondary coated negative electrode material (85.2%) is combined with a sulfide electrolyte (14% Li). 5.5 PS 4.5 Cl 1.5 A dry-process negative electrode sheet is prepared by mixing PTFE (0.8%) with copper foil and dry-rolling it onto copper foil, with an areal density of 15 mg / cm³. 2 Compacted to 1.45 g / cm³ 3 ;

[0149] 5. Preparation of the intermediate electrolyte layer: The sulfide electrolyte (99% Li) is prepared... 5.5 PS 4.5 Cl 1.5 The mixture of 1% PTFE and 1% was rolled to prepare a dry electrolyte membrane with a thickness of 50 μm.

[0150] 6. Battery preparation: The positive electrode, electrolyte membrane and negative electrode are sequentially bonded together, encapsulated with aluminum-plastic film, and subjected to 500 MPa isostatic pressure treatment to obtain a soft-pack battery.

[0151] Comparative Examples 1 to 4

[0152] The preparation method is the same as in the examples, and the specific composition is shown in Tables 1 and 2. Specifically, the coating layers of both the positive and negative electrodes in Comparative Example 1 do not contain one-dimensional carbon materials, but contain carbon black SP with a diameter of 20 nm; the coating layer in Comparative Example 2 does not contain a second solid electrolyte; the electrolyte in the coating layer of Comparative Example 3 is a halide solid electrolyte; and the coating layer of Comparative Example 4 does not contain a solid electrolyte or one-dimensional carbon materials, but instead contains dot-like carbon black SP with a diameter of 20 nm.

[0153] The batteries of Examples 1-18 and Comparative Examples 1-4 were tested:

[0154] Performance 1-Rate Performance Test Method:

[0155] Charge the battery at 0.05C to the upper limit voltage, cut off the current at 0.05C, and then discharge it at 0.05C to the lower limit voltage of 2.5V. This is one cycle, and the charge-discharge cycle is repeated 3 times. The discharge capacity C0 of the third cycle is recorded. Then, charge the battery at 1C constant current to the upper limit voltage, charge it at constant voltage to the cutoff current at 0.05C, and then discharge it at 1C to the lower limit voltage of 2.5V. This is one cycle, and the cycle is repeated 5 times. The discharge capacity C1 of the fifth cycle is recorded. Rate performance = C1 / C0. The results are shown in Table 3.

[0156] The cathode material in Examples 1-3, 10-12, and 15 is NCM, and the upper limit voltage of the battery is 4.25 V; the cathode material in Examples 4-6 and 13-14 is lithium iron phosphate, and the upper limit voltage of the battery is 3.65 V; the cathode material in Examples 7-9 and 16-18 is lithium cobalt oxide, and the upper limit voltage of the battery is 4.25 V.

[0157] Performance 2-cycle testing method:

[0158] The prepared battery was charged at 0.05C to the upper limit voltage and cut off at 0.05C. Then it was discharged at 0.05C to the lower limit voltage of 2.5V. This was repeated as one cycle, and the charge-discharge cycle was repeated 3 times. The discharge capacity C0 of the third cycle was taken as the battery's discharge capacity. Then it was charged at 1C constant current to the upper limit voltage and charged at constant voltage to the cutoff current of 0.05C. Then it was discharged at 1C to the lower limit voltage of 2.5V. This was repeated 100 times to obtain the discharge capacity C2 of the 100th cycle. The capacity retention rate of the battery after 100 cycles was calculated as C2 / C0×100%. The results are shown in Table 3.

[0159] The cathode material in Examples 1-3, 10-12, and 15 is NCM, and the upper limit voltage of the battery is 4.25 V; the cathode material in Examples 4-6 and 13-14 is lithium iron phosphate, and the upper limit voltage of the battery is 3.65 V; the cathode material in Examples 7-9 and 16-18 is lithium cobalt oxide, and the upper limit voltage of the battery is 4.25 V.

[0160] Pretreatment: Discharge the battery at 0.33C to the lower limit voltage of 2.5V, remove the empty battery, disassemble the electrode, soak the electrode in dimethyl carbonate (DMC) solution for 4 hours, and then air dry;

[0161] SEM testing: A layer of conductive adhesive was first applied to the sample holder, and the sample was then attached to the sample holder. CP argon ion polishing was performed, followed by the deposition of a conductive film. The tools and sample stage were wiped with anhydrous ethanol. A certain amount of the sample to be tested was placed on the sample stage. The sample was observed under a scanning electron microscope (SEM). The magnification was adjusted to a suitable level using the SEM, specifically, a magnification of 10 kx. The extension length, diameter, and other parameters of all one-dimensional carbon materials within the uniform magnification area were calculated, and their average values ​​were obtained to obtain the average size of the one-dimensional carbon material extending from the coating layer, the diameter of the one-dimensional carbon material, and the length of the one-dimensional carbon material. The results are shown in Table 3.

[0162] Methods for testing coating thickness and core diameter:

[0163] 1) Pretreatment: Discharge the battery at 0.33C to the lower limit voltage of 2.5V, take the electrode of the lithium-ion battery in the empty state, and scrape off the active material powder on the surface of the electrode with a ceramic knife;

[0164] 2) The scraped active material powder is uniformly dispersed in ethanol, water, or n-heptane (the specific type of dispersion solvent is determined to avoid dissolving and damaging the coating layer). When using ethanol or water for dispersion, the dissolved sulfide electrolyte must be removed by filtration, and then the dispersion is repeated. Afterwards, a microgrid copper mesh sample is prepared and subjected to TEM (transmission electron microscopy). In the TEM observation field, lines are drawn along the long and short axes of the particle core, the diameter is measured, and the average value is calculated to obtain the particle diameter of the active material core. Three different locations are selected on a single positive electrode active material (the number of selections can be determined based on the case), and the thickness of the coating layer on the outer surface of the core is measured and the average value is calculated to obtain the coating layer thickness of the active material particle. The results are shown in Table 1.

[0165] Table 1 Composition of the positive electrode plate

[0166]

[0167]

[0168]

[0169]

[0170] Table 2 Composition of the negative electrode

[0171]

[0172]

[0173]

[0174]

[0175] Table 3 Performance Test Results

[0176]

[0177] Compared with Comparative Examples 1-4, Examples 1-18 show that in Comparative Example 4, neither the positive nor negative electrode active materials were coated, and no one-dimensional carbon material was added, resulting in poor rate performance and cycle performance. In Comparative Example 1, only the surface of the positive and negative electrode active materials was coated with a polymer electrolyte layer, which improved the cycle performance but resulted in even lower rate performance. In Comparative Example 2, the surface of the positive and negative electrode active materials was not coated with a polymer electrolyte layer, but only one-dimensional carbon material was provided. Due to the formation of a conductive network, the rate performance and cycle performance of the battery were slightly improved. In Comparative Example 3, the surface of both the positive and negative electrode active materials was provided with one-dimensional carbon material, but only the surface of the positive electrode material was coated with a halide, which improved the rate performance of the battery, but resulted in poor cycle performance.

[0178] As can be seen from Examples 1 to 18, by coating the surface of the positive and negative electrode active materials with a polymer electrolyte layer and providing a one-dimensional carbon material extending out of the coating layer, the 1C / 0.05C rate performance of the battery can reach 70% to 87%, and the capacity retention rate after 100 cycles is greater than or equal to 80%.

[0179] Furthermore, by optimizing the coating layer on the surface of the positive electrode active material and the size of the one-dimensional carbon material, the battery's 1C / 0.05C rate performance reaches 77%~87%, and the capacity retention rate after 100 cycles is greater than or equal to 80%.

[0180] Furthermore, by simultaneously optimizing the coating layer on the surface of the positive and negative electrode active materials and the size of the one-dimensional carbon material, the battery's 1C / 0.05C rate performance reaches 82%~87%, and the capacity retention rate after 100 cycles is greater than or equal to 82%.

[0181] In summary, the battery electrode provided by this invention can improve the rate performance and increase the cycle life of the battery.

[0182] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A battery electrode for solid-state batteries, characterized in that, Including the first material and the first solid electrolyte; The first material includes a core and a coating layer disposed on the surface of the core; the core is an active material; the coating layer includes a conductive agent and a second solid electrolyte; the conductive agent includes a one-dimensional carbon material, and at least one end of the one-dimensional carbon material extends out of the surface of the coating layer. The first solid electrolyte includes a sulfide solid electrolyte; The second solid electrolyte includes a polymer solid electrolyte; The coating layer includes a first coating layer and a second coating layer; the first coating layer is disposed between the core and the second coating layer; the first coating layer includes a first binder and the conductive agent; the second coating layer includes a second solid electrolyte; the one-dimensional carbon material extends out of the second coating layer; The average size of the one-dimensional carbon material extending out of the coating layer is 1 to 10 times the shortest distance between the coating layers of adjacent first materials.

2. The battery electrode according to claim 1, characterized in that, The average size of the one-dimensional carbon material extending out of the coating layer is 1~15 μm.

3. The battery electrode according to claim 1, characterized in that, The diameter of the core is 0.2~20 μm; And / or, the shortest distance between adjacent coating layers of the first material is 0.5~10μm; And / or, the thickness of the coating layer is 50 nm to 1 μm.

4. The battery electrode according to claim 1, characterized in that, The diameter of the one-dimensional carbon material is 1~400 nm; And / or, the length of the one-dimensional carbon material is 3~30 μm.

5. The battery electrode according to claim 1, characterized in that, The mass ratio of the first material to the first solid electrolyte is (80~90):(10~20).

6. The battery electrode according to claim 1, characterized in that, The mass content of the conductive agent in the first coating layer is 10%~95%.

7. The battery electrode according to claim 1, characterized in that, The one-dimensional carbon material is selected from carbon fibers and / or carbon nanotubes.

8. The battery electrode according to claim 1, characterized in that, The second solid electrolyte comprises a polymer and a lithium salt; or comprises a polymer, a lithium salt, and a filler. The lithium salt has a mass of 1% to 300% of the polymer mass; The mass of the filler is 1% to 30% of the polymer mass.

9. The battery pole piece of claim 8, wherein, The active material is a positive electrode active material; The polymer is selected from one or more of polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, polyethylene glycol, polyethylene glycol methacrylate, polysiloxane, polyacrylonitrile, polycyanoacrylate and polyphosphazene; The lithium salt is selected from one or more of lithium bis(trifluorosulfonyl)imide, lithium hexafluorophosphate, lithium bis(oxalato)borate, lithium perchlorate, lithium bis(fluorosulfonyl)imide, lithium hexafluoroarsenate, and lithium tetrafluoroborate. The filler is selected from one or more of lithium aluminum titanium phosphate, lithium lanthanum zirconium oxide, lithium lanthanum zirconium titanium oxide, lithium lanthanum titanium oxide, silicon dioxide, and aluminum oxide; The mass of the lithium salt is 80% to 100% of the polymer mass; The mass of the filler is 1% to 20% of the polymer mass.

10. The battery electrode according to claim 9, characterized in that, The positive electrode active material is selected from one or more of lithium iron phosphate, lithium cobalt oxide, lithium nickel manganese oxide, lithium manganese iron phosphate, lithium manganese oxide, and lithium nickel cobalt manganese oxide. The diameter of the core is 0.5~20 μm; The diameter of the one-dimensional carbon material is 10~200 nm.

11. The battery electrode according to claim 9, characterized in that, The mass ratio of the core to the second solid electrolyte is 90:10 to 97:

3.

12. The battery electrode according to claim 8, characterized in that, The active material is a negative electrode active material; The polymer is selected from one or more of polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, polyethylene glycol, polysiloxane, polyacrylonitrile, and polyphosphazene. The lithium salt is selected from one or more of lithium bis(trifluorosulfonyl)imide, lithium hexafluorophosphate, lithium bis(oxalato)borate, lithium perchlorate, lithium bis(fluorosulfonyl)imide, lithium hexafluoroarsenate, and lithium tetrafluoroborate. The filler is selected from one or more of lithium lanthanum zirconium oxide, lithium lanthanum zirconium titanium oxide, lithium lanthanum titanium oxide, silicon dioxide, and alumina; The mass of the lithium salt is 20% to 100% of the polymer mass; The mass of the filler is 1% to 20% of the polymer mass.

13. The battery electrode according to claim 12, characterized in that, The negative electrode active material is selected from one or more of silicon-based materials, graphite, and lithium titanate; The diameter of the core is 0.2~20 μm; The diameter of the one-dimensional carbon material is 5~150 nm.

14. The battery pole piece of claim 12, wherein, The mass ratio of the core to the second solid electrolyte is 85:15 to 90:

10.

15. The battery pole piece of any one of claims 1-14, wherein, The diameter of the core is 3~15μm; The length of the one-dimensional carbon material is 5~20 μm; The average size of the one-dimensional carbon material extending out of the coating layer is 2~10 μm.

16. A method for preparing a battery electrode according to claim 1, characterized in that, Includes the following steps: S1) The active material, the second solid electrolyte, and the conductive agent are mixed in a solvent and then spray-dried to obtain the first material; S2) The first material is mixed with the first solid electrolyte and pressed into shape to obtain a battery electrode for solid-state batteries.

17. The method of claim 16, wherein the method further comprises, Step S1) specifically involves: A1) The active material, the first binder and the conductive agent are dispersed and mixed in a solvent, and then spray-dried and aged by heating to obtain a primary coating material; A2) The primary coating material is mixed with the second solid electrolyte in a solvent and then spray-dried to obtain the first material.

18. A solid state battery, characterized by This includes the battery electrode sheet according to any one of claims 1 to 15 or the battery electrode sheet prepared by the preparation method according to claim 16 or 17.

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