An all-solid-state lithium ion battery and a preparation method thereof

Abstract

The application discloses a kind of full solid-state lithium ion batteries and preparation method thereof, a kind of full solid-state lithium ion batteries, including modified silicon-based negative electrode layer, solid electrolyte layer, modified positive electrode layer in turn;The modified silicon-based negative electrode layer is obtained by uniformly mixing modified silicon-based particles, conductive agent and binder by roller pressing, wherein the modified silicon-based particles are composed of silicon-based particles and low-pressure resistant ceramic electrolyte layer coated on the surface of silicon-based particles, the thickness of the modified silicon-based negative electrode layer is 20-100 microns;The low-pressure resistant ceramic electrolyte selects garnet-type oxide, and the garnet-type oxide structure general formula is Li 7‑ x La3Zr 2‑x M x O 12 In the formula, M is selected from at least one of Nb or Ta, wherein 0.1≤x≤0.7;The silicon-based particles are composed of silicon, or silicon monoxide, and graphite and surface-coated carbon.The full solid-state lithium ion battery of the application uses silicon-based negative electrode, improves the negative electrode ion conductance, ensures that the solid-state battery has excellent cycle life and safety performance, and has very high practical value.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lithium battery, in particular to a kind of full solid-state lithium ion battery and preparation method thereof. BACKGROUND

[0002] Lithium ion battery has higher specific energy, especially polymer lithium ion battery, which can realize the thin shape of rechargeable battery. Because the volume specific energy and mass specific energy of lithium ion battery are high, it is rechargeable and pollution-free, with the three major characteristics of current battery industry development, so it has faster growth in developed countries. The development of telecommunications and information market, especially the large use of mobile phones and notebook computers, brings market opportunities for lithium ion battery. Among lithium ion batteries, polymer lithium ion battery will gradually replace liquid electrolyte lithium ion battery and become the mainstream of lithium ion battery due to its unique advantage in safety.

[0003] In the prior art, lithium metal is often used as the negative electrode of lithium ion battery, and due to the inevitable lithium dendrite, lithium dendrite short circuit occurs in the use process of solid-state battery, which deteriorates the cycle life and safety performance. SUMMARY

[0004] To solve the above technical problems, the present application provides a kind of full solid-state lithium ion battery, silicon-based negative electrode is adopted, the negative electrode ion conductance is improved, the solid-state battery has excellent cycle life and safety performance, and has very high practical value in product application.

[0005] Further, it is necessary to provide a preparation method of the full solid-state lithium ion battery.

[0006] The technical scheme provided by the present application is as follows:

[0007] A full solid-state lithium ion battery,

[0008] It comprises a modified silicon-based negative electrode layer, a solid-state electrolyte layer and a modified positive electrode layer in sequence.

[0009] The modified silicon-based negative electrode layer is obtained by uniformly mixing modified silicon-based particles, conductive agent and binder and then rolling, wherein the modified silicon-based particles are composed of silicon-based particles and a low-voltage resistant ceramic electrolyte layer coated on the surface of the silicon-based particles, and the thickness of the modified silicon-based negative electrode layer is 20-100 microns.

[0010] The low-voltage resistant ceramic electrolyte is selected from garnet-type oxides, and the garnet-type oxide has a general structure of Li 7-x La3Zr 2_x M x O 12 , wherein M is selected from at least one of Nb or Ta, and 0.1≤x≤0.7.

[0011] The silicon-based particles are commercial materials, which are composed of silicon, or silicon monoxide, and graphite and carbon coating on the surface, and the particle size of the silicon-based negative electrode is 0.5-10 microns, and the specific capacity is 400-2000 mAh / g;

[0012] The weight ratio of the low-voltage resistant ceramic electrolyte to the silicon-based particles is (1-2):100.

[0013] The weight ratio of the modified silicon-based particles, the conductive agent and the binder is (92-95):(2-3):(3-5).

[0014] The modified silicon-based negative electrode layer is obtained by uniformly mixing and rolling the modified silicon-based negative electrode particles, the conductive agent and the binder, and as preferred, the dry rolling process is used to obtain the negative electrode sheet, which can reduce the processing cost, reduce pollution, improve the compaction density of the negative electrode, and the thickness of the modified silicon-based negative electrode layer is 20-100 microns, wherein the weight ratio of the modified silicon-based negative electrode particles, the conductive agent and the binder is (92-95):(2-3):(3-5).

[0015] The modified silicon-based negative electrode particles are composed of silicon-based particles and a low-voltage resistant ceramic electrolyte on the surface, and the weight ratio of the low-voltage resistant ceramic electrolyte to the silicon-based particles is (1-2):100, and within this range, the low-voltage resistant ceramic electrolyte can uniformly, completely and conformally coat the silicon-based particles, and the so-called conformal coating refers to the coating material that can coat the morphology, texture and grain of the coated material.

[0016] As preferred, the low-voltage resistant ceramic electrolyte is subjected to sanding treatment to reduce the particle size to 10-100 nanometers, which can better uniformly, completely and conformally coat the particles.

[0017] When the garnet-type ceramic electrolyte contacts the silicon-based negative electrode and the sulfide ceramic, it can maintain chemical / electrochemical stability, and the ceramic electrolyte is a lithium ion conductor, and the coating does not affect the rapid transport of lithium ions at the negative electrode / solid-state electrolyte interface, at the same time, the garnet ceramic electrolyte coating layer acts as an artificial SEI film, which can promote the uniform diffusion of lithium ions and inhibit the formation of lithium dendrites in the sulfide ceramic electrolyte, thus improving the interface chemical / electrochemical stability and the interface lithium ion transport.

[0018] The solid-state electrolyte layer is composed of a ceramic electrolyte, a piezoelectric material and a polymer binder, and the ceramic electrolyte, the piezoelectric material and the polymer binder are uniformly mixed to obtain the solid-state electrolyte layer by rolling, and as preferred, the dry rolling process is used to obtain the solid-state electrolyte layer, which can reduce the processing cost, reduce pollution, and improve the density of the solid-state electrolyte layer, and improve the lithium ion conductivity and mobility.

[0019] The conductive agent is selected from at least one of acetylene black, carbon nanotubes, graphene, and carbon fiber.

[0020] The solid electrolyte layer comprises a ceramic electrolyte, a piezoelectric material, and a polymer binder. The ceramic electrolyte, piezoelectric material, and polymer binder are uniformly mixed and rolled to obtain the solid electrolyte layer. The solid electrolyte layer contains 95%-98% ceramic electrolyte by weight, 0.5%-2% piezoelectric material by weight, and 1.5%-3% binder by weight.

[0021] The ceramic electrolyte is selected from sulfides, specifically Li6PS5Cl, Li3PS4, and Li7P3S. 11 Li4SnS4, Li 10 GeP2S 12 One or more combinations thereof.

[0022] The term "derivative" refers to the product of doping the aforementioned sulfides at P, S, Sn, and Ge sites. The doping concentration is generally greater than or equal to 0.5% and less than or equal to 20%. For example, doping Li6PS5Cl at the S site with Cl yields Li. 5.5 PS 4.5 C l1.5 , for Li 10 GeP2S 12 Li was obtained by doping Si at Ge sites. 10 Ge 0.9 Si 0.1 P2S 12 Li3P was obtained by doping Li3PS4 with Sb at the P site. 0.95 Sb 0.05 S4, the sulfide has high room temperature conductivity, preferably, the room temperature lithium-ion conductivity of the sulfide is higher than 10. –3 S / cm, preferably, the sulfide particle size is 0.5 micrometers to 5 micrometers. Commercial sulfide materials can be ball-milled or sand-milled to obtain materials of the required size.

[0023] The piezoelectric material is selected from, but not limited to, LiTaO3, LiNbO3, NaNbO3, and NaTaO3. Due to the large stress generated by the silicon-based anode during charging and discharging, the piezoelectric material will generate a piezoelectric field under the action of stress. This piezoelectric field is beneficial to improving the lithium ion diffusion rate of the sulfide ceramic electrolyte, while suppressing the formation of lithium dendrites, and further improving the interfacial compatibility between the sulfide ceramic electrolyte and the positive and negative electrodes.

[0024] The modified positive electrode layer is obtained by uniformly mixing modified positive electrode active particles, a conductive agent, a binder and a ceramic electrolyte and then rolling, wherein the modified positive electrode active particles are composed of positive electrode active particles and a high-pressure-resistant ceramic electrolyte coated on the surface of the positive electrode active particles, and the thickness of the modified positive electrode layer is 50-200 microns.

[0025] The ceramic electrolyte is a sulfide selected from one or more combinations of Li6PS5Cl, Li3PS4, Li7P3S 11 , Li4SnS4, Li 10 GeP2S 12 .

[0026] The high-pressure-resistant ceramic electrolyte includes a NASICON-type oxide or a metal halide; such a ceramic electrolyte has chemical / electrochemical stability when in contact with a sulfide ceramic electrolyte and an oxide positive electrode, and such a ceramic electrolyte is a lithium ion conductor, thus improving the interface chemical / electrochemical stability and the interface lithium ion transport, in addition, the high-pressure-resistant ceramic electrolyte coating can also inhibit the generation of lithium dendrites in the sulfide electrolyte and improve the thermal stability of the positive electrode material.

[0027] The NASICON-type oxide has a general structure of Li 1+z Al z N 2-z (PO4)3, wherein N is selected from at least one of Ti, Ge or Zr, and 0.2≤z≤0.6.

[0028] The metal halide has a general structure of Li3ZA6, wherein Z is selected from at least one of Y, Sc, Er or In, and A is selected from at least one of F, Cl, Br or I.

[0029] The weight ratio of the high-pressure-resistant ceramic electrolyte to the positive electrode active particles is 0.5:100-5:100, and within this range, the high-pressure-resistant ceramic electrolyte can uniformly, completely and conformally coat the positive electrode active material particles; the so-called conformal coating means that the coating material can coat the morphology, texture and grain of the coated material; preferably, the low-pressure-resistant ceramic electrolyte is subjected to sanding treatment to reduce the particle size to 10-100 nanometers, and within this range, the coating can be more uniform, complete and conformal.

[0030] The weight ratio of the modified positive electrode active particles, the conductive agent, the binder, and the ceramic electrolyte is (93-98):(0.5-2):(1-2):(0.5-3); as preferred, the positive electrode sheet is obtained by using a dry rolling process, which can reduce the processing cost, reduce pollution, and improve the compaction density of the positive electrode; as preferred, the thickness of the modified positive electrode layer is 50-200 microns; as preferred, the ceramic electrolyte herein is the same as the ceramic electrolyte in the solid-state electrolyte layer, which is a sulfide-based ceramic;

[0031] The thickness of the solid-state electrolyte layer is 10-100 microns.

[0032] The positive electrode active particles are lithium-containing oxides, and are at least one of lithium cobaltate, lithium manganate, lithium nickel manganate, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, nickel cobalt manganese ternary material, nickel cobalt aluminum ternary material, and lithium-rich layered material.

[0033] The binder used in the modified silicon-based negative electrode layer, the solid-state electrolyte layer, or the positive electrode layer is fluorinated polyolefin, and is selected from polyvinylidene fluoride, polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene copolymer, and polyperfluoroethylene propylene. As preferred, it is selected from polytetrafluoroethylene, which can be fiberized during the rolling process, effectively bonding sulfide ceramic particles and piezoelectric materials, improving the strength and flexibility of the ceramic electrolyte film, and the processability of the ceramic film.

[0034] A full solid-state lithium ion battery as described above is prepared by the following steps:

[0035] 1) The silicon-based negative electrode and the low-voltage-resistant ceramic electrolyte are uniformly mixed at a weight ratio of 100:(1-2), the low-voltage-resistant ceramic electrolyte is uniformly, completely, and conformally coated on the surface of the silicon-based negative electrode particles by using a mechanical fusion method to obtain modified silicon-based negative electrode particles, and then the modified silicon-based particles, the conductive agent, and the binder are uniformly mixed at a weight ratio of (92-95):(2-3):(3-5) to obtain a modified silicon-based negative electrode layer by rolling;

[0036] 2) The positive electrode active particles and the high-voltage-resistant ceramic electrolyte are uniformly mixed at a weight ratio of 100:(1-2), the high-voltage-resistant ceramic electrolyte is uniformly, completely, and conformally coated on the surface of the positive electrode active particles by using a mechanical fusion method to obtain modified positive electrode active particles, and then the modified positive electrode active particles, the conductive agent, the binder, and the ceramic electrolyte are uniformly mixed at a weight ratio of (93-98):(0.5-2):(1-2):(0.5-3) to obtain a modified positive electrode layer by rolling;

[0037] 3) The ceramic electrolyte, the polymer binder, and the piezoelectric material are uniformly mixed at a weight ratio of (95-98):(0.5-2):(1.5-3) to obtain a solid-state electrolyte layer by rolling;

[0038] 4) The modified silicon-based negative electrode layer, the solid-state electrolyte layer, and the modified positive electrode layer are laminated, rolled, and packaged to assemble the all-solid-state lithium ion battery.

[0039] The mechanical fusion time in steps 1) and 2) is 0.5-5 hours, and the fusion atmosphere is nitrogen, argon, or helium.

[0040] In steps 1) and 2), as a preference, the coating is performed using a mechanical fusion method, which can uniformly, completely, and conformally coat the coating material particles on the surface of the coated material particles, and has the advantages of simple process, low cost, large-scale production, and improved compaction density of the positive and negative electrodes. Further preferably, after the mechanical fusion, heat treatment is performed in an inert atmosphere, the heat treatment time is 0.5-2 hours, and the heat treatment temperature is 200-400℃. After the heat treatment, the bonding force between the coating material and the coated material can be further improved.

[0041] Compared with the prior art, the all-solid-state lithium ion battery provided by the application uses a modified silicon-based negative electrode layer as the negative electrode layer, and the surface of the silicon-based negative electrode is modified with a low-voltage-resistant ceramic electrolyte. This can improve the interface stability between the silicon-based negative electrode and the ceramic electrolyte, promote the transmission of lithium ions in the charging and discharging process, and inhibit the formation of lithium dendrites in the solid-state electrolyte layer. The positive electrode is coated with a high-voltage-resistant ceramic electrolyte, which can improve the interface performance between the solid-state electrolyte and the positive electrode, improve the stability of the positive electrode material, and inhibit the formation of lithium dendrites in the solid-state electrolyte layer. The obtained all-solid-state lithium ion battery has the advantages of high energy density, high safety, and long service life. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0043] Figure 1 The charge-discharge curve of the solid-state lithium battery prepared in Example 1. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0045] Sources of materials used in the embodiments of the invention:

[0046] Silicon-based particles: battery grade, BTR DXB5, specific capacity 450 mAh / g;

[0047] LiCoO2: battery grade, Hunan Shanshan;

[0048] LiNi 0.5 Co 0.2 Mn 0.3 O2: battery grade, Guizhou Zhenhua;

[0049] LiNi 0.8 Co 0.1 Mn 0.1 O2: battery grade, Guizhou Zhenhua;

[0050] LiFe 0.4 Mn 0.6 PO4: battery grade, D 50 = 0.936 microns, Kurimoto;

[0051] Li 6.5 La3Zr 1.5 Nb 0.5 O 12 : battery grade, D 50 = 0.5 ± 0.05 microns, Shenzhen Keyi Zhida Technology Co., Ltd.;

[0052] Li6PS5Cl: battery grade, 2-10 microns, Shenzhen Keyi Zhida Technology Co., Ltd.;

[0053] Li3InCl6: battery grade, Shenzhen Keyi Zhida Technology Co., Ltd.;

[0054] Li 1.3 Al 0.3 Ti 1.7 (PO4)3: battery grade, D 50 = 0.6 ± 0.05 microns, Shenzhen Keyi Zhida Technology Co., Ltd.;

[0055] Li 10 GeP2S 12 : battery grade, 0.5-5 microns, Shenzhen Keyi Zhida Technology Co., Ltd.;

[0056] Li7P3S 11 : battery grade, 0.5-10 microns, Shenzhen Keyi Zhida Technology Co., Ltd.;

[0057] LiNbO3: Aladdin, 99.99%

[0058] LiTaO3: Aladdin, 99.99%

[0059] NaNbO3: Aladdin, 99.9%

[0060] Polytetrafluoroethylene: battery grade, molecular weight from several ten-thousands to 100 million, Japan Daikin.

[0061] Example 1

[0062] The battery was prepared as follows:

[0063] 1) The silicon-based negative electrode and Li 6.5 La3Zr 1.5 Nb 0.5 O 12 were mixed in a weight ratio of 100:1, and a silicon-based negative electrode particle coated with Li 6.5 La3Zr 1.5 Nb 0.5 O 12 on the surface was obtained by mechanical fusion under an argon atmosphere at 300°C for 1 hour. The modified silicon-based material, polytetrafluoroethylene, and acetylene black were mixed in a weight ratio of 94:3:3, and a modified silicon-based negative electrode layer was prepared by rolling.

[0064] 2) The LiCoO2 material and Li 1.3 Al 0.3 Ti 1.7 (PO4)3 were mixed in a weight ratio of 100:2, and LiCoO2 positive electrode particles coated with Li 1.3 Al 0.3 Ti 1.7 (PO4)3 on the surface were obtained by mechanical fusion under an argon atmosphere at 300°C for 1 hour. The modified LiCoO2 material, acetylene black, polytetrafluoroethylene, and Li6PS5Cl were mixed in a weight ratio of 94:1.5:1.5:3, and a modified LiCoO2 positive electrode layer was prepared by rolling.

[0065] 3) Li6PS5Cl, LiTaO3, and polytetrafluoroethylene were mixed in a weight ratio of 97:1:2, and a Li6PS5Cl solid-state electrolyte layer with a thickness of 30 microns was obtained by rolling.

[0066] 4) The modified silicon-based negative electrode layer, Li6PS5Cl solid-state electrolyte layer, and modified LiCoO2 positive electrode layer were laminated, rolled, and packaged to assemble a full solid-state lithium ion battery.

[0067] Performance test:

[0068] The battery was charged and discharged at 60°C, 2.5-4.2V, and 0.1C (1C is defined as 140mA / g), and the charge and discharge curves are shown in Figure 1 The discharge capacity was 111mAh / g, and the capacity retention rate was 89% after 50 cycles.

[0069] Example 2

[0070] The battery was prepared by the following method:

[0071] 1) The silicon-based negative electrode and Li 6.5 La3Zr 1.5 Nb 0.5 O 12 were mixed at a weight ratio of 100:1.5, and a silicon-based negative electrode particle coated with Li 6.5 La3Zr 1.5 Nb 0.5 O 12 on the surface was obtained by mechanical fusion under an argon atmosphere at 300°C for 1 hour. The modified silicon-based material, polytetrafluoroethylene, and acetylene black were mixed at 92:3:5, and a modified negative electrode layer was prepared by rolling.

[0072] 2) The LiNi 0.5 Co 0.2 Mn 0.3 O2 material and Li 1.3 Al 0.3 Ti 1.7 (PO4)3 were mixed at a weight ratio of 100:1.5, and uniformly heated under an argon atmosphere at 300°C for 1 hour. LiNi 1.3 Al 0.3 Ti 1.7 (PO4)3-coated LiNi 0.5 Co 0.2 Mn 0.3 O2 positive electrode particles were obtained by mechanical fusion. The modified LiNi 0.5 Co 0.2 Mn 0.3 O2 material, acetylene black, polytetrafluoroethylene, and Li7P3S 11 were mixed at a weight ratio of 93:2:2:3, and a modified LiNi 0.5 Co 0.2 Mn 0.3 O2 positive electrode layer was prepared by rolling.

[0073] 3) Li7P3S 11 , LiNbO3, and polytetrafluoroethylene were mixed at a weight ratio of 98:0.5:1.5, and a Li7P3S 11 solid-state electrolyte layer with a thickness of 30 microns was obtained by rolling.

[0074] 4) The modified silicon-based negative electrode layer, Li7P3S 11 solid-state electrolyte layer, and modified LiNi 0.5 Co 0.2 Mn 0.3O2 positive electrode layer is laminated, rolled and packaged to assemble a full solid-state lithium ion battery.

[0075] Performance test:

[0076] The battery is charged and discharged at 60℃, 3-4.2V, 0.1C (1C is defined as 160mA / g), the discharge capacity is 125mAh / g, and the capacity retention rate is 87% after 50 cycles.

[0077] Example 3

[0078] The battery is prepared by the following method:

[0079] 1) Commercial silicon-based negative electrode and Li 6.5 La3Zr 1.5 Nb 0.5 O 12 are mixed at a weight ratio of 100:2, and a mechanically fused method is used to obtain silicon-based negative electrode particles coated with Li 6.5 La3Zr 1.5 Nb 0.5 O 12 , and the above modified silicon-based material, polytetrafluoroethylene, and acetylene black are mixed uniformly at 95:2:3, and a rolling method is used to prepare a modified negative electrode layer;

[0080] 2) LiNi 0.8 Co 0.1 Mn 0.1 O2 material and Li3InCl6 are mixed uniformly at a weight ratio of 100:1, and heated at 300℃ in an argon atmosphere for 1 hour, and a mechanically fused method is used to obtain LiNi 0.8 Co 0.1 Mn 0.1 O2 positive electrode particles coated with Li3InCl6, and the above modified LiNi 0.8 Co 0.1 Mn 0.1 O2 material, acetylene black, polytetrafluoroethylene, and Li 10 GeP2S 12 are mixed at a weight ratio of 98:0.5:1:0.5, and a rolling method is used to prepare a modified LiNi 0.8 Co 0.1 Mn 0.1 O2 positive electrode layer;

[0081] 3) Li 10 GeP2S 12 , NaNbO3, and polytetrafluoroethylene are mixed uniformly at a weight ratio of 95:2:3, and a rolling method is used to obtain a Li 10 GeP2S 12 solid-state electrolyte layer with a thickness of 30 microns;

[0082] 4) The modified silicon-based negative electrode layer, Li 10 GeP2S 12 solid electrolyte layer, modified LiNi 0.8 Co 0.1 Mn 0.1 O2 positive electrode layer are laminated, rolled, and packaged to assemble a full solid-state lithium ion battery.

[0083] Performance test:

[0084] The battery is charged and discharged at 60°C, 3-4.2V, and 0.1C (1C is defined as 200mA / g), and the discharge capacity is 172mAh / g. After 50 cycles, the capacity retention rate is 85%.

[0085] Example 4

[0086] The battery is prepared as follows:

[0087] 1) The silicon-based negative electrode and Li 6.5 La3Zr 1.5 Nb 0.5 O 12 are mixed at a weight ratio of 100:1, and a mechanically fused method is used to obtain silicon-based negative electrode particles coated with Li 6.5 La3Zr 1.5 Nb 0.5 O 12 , and the above modified silicon-based material, polytetrafluoroethylene, and acetylene black are mixed uniformly at a ratio of 93.5:2.5:4, and a modified silicon-based negative electrode layer is prepared by rolling;

[0088] 2) The LiFe 0.4 Mn 0.6 PO4 material is mixed uniformly with Li3InCl6 at a weight ratio of 100:2, and heated at 300°C in an argon atmosphere for 1 hour, and a mechanically fused method is used to obtain LiFe 0.4 Mn 0.6 PO4 positive electrode particles coated with Li3InCl6, and the above modified LiFe 0.4 Mn 0.6 PO4 material, acetylene black, polytetrafluoroethylene, and Li6PS5Cl are mixed at a weight ratio of 95.5:1.5:2:1, and a modified LiFe 0.4 Mn 0.6 PO4 positive electrode layer is prepared by rolling;

[0089] 3) Li6PS5Cl, LiTaO3, and polytetrafluoroethylene are mixed uniformly at a weight ratio of 95:2:3, and a Li6PS5Cl solid electrolyte layer with a thickness of 30 microns is obtained by rolling.

[0090] 4) Stack the modified silicon-based negative electrode layer, Li6PS5Cl solid-state electrolyte layer, modified LiFe 0.4 Mn 0.6 PO4 positive electrode layer, roll, package and assemble a full solid-state lithium ion battery.

[0091] Performance test:

[0092] The battery was charged and discharged at 60°C, 3-4.2V, 0.1C (1C defined as 170mA / g), and the discharge capacity was 132mAh / g. After 50 cycles, the capacity retention rate was 88%.

[0093] Comparative Example 1

[0094] The process of making a solid-state battery was the same as in Example 1, except that the surface of the silicon-based negative electrode was not coated with Li 6.5 La3Zr 1.5 Nb 0.5 O 12 .

[0095] After electrochemical testing under the same conditions, the discharge capacity was 98mAh / g, and the capacity retention rate was 74%.

[0096] Comparative Example 2

[0097] The process of making a solid-state battery was the same as in Example 1, except that the surface of the silicon-based negative electrode was coated with the same weight of ZrO2.

[0098] After electrochemical testing under the same conditions, the discharge capacity was 95mAh / g, and the capacity retention rate was 76%.

[0099] Comparative Example 3

[0100] The process of making a solid-state battery was the same as in Example 1, except that the surface of the LiCoO2 positive electrode was coated with Li 1.3 Al 0.3 Ti 1.7 (PO4)3, but without heat treatment (without heating at 300°C in an argon atmosphere for 1 hour).

[0101] After electrochemical testing under the same conditions, the discharge capacity was 103mAh / g, and the capacity retention rate was 82%.

[0102] Comparative Example 4

[0103] The process of making a solid-state battery was the same as in Example 1, except that the surface of the LiCoO2 positive electrode was not coated with Li 1.3 Al 0.3 Ti 1.7 (PO4)3.

[0104] The discharge capacity is 96 mAh / g and the capacity retention rate is 71% after electrochemical test under the same condition.

[0105] Comparative Example 5

[0106] The preparation process of the solid-state battery is the same as that of Example 1, except that the surface coating layer of the LiCoO2 cathode is Al2O3. The capacity is 101 mAh / g after electrochemical test under the same condition.

[0107] The capacity retention rate is 76% after electrochemical test under the same condition.

[0108] Comparative Example 6

[0109] The preparation process of the solid-state battery is the same as that of Example 1, except that the surface of the LiCoO2 cathode particle is not coated with Li 1.3 Al 0.3 Ti 1.7 (PO4)3, and the surface of the silicon-based anode is not coated with Li 6.5 La3Zr 1.5 Nb 0.5 O 12 .

[0110] The discharge capacity is 91 mAh / g and the capacity retention rate is 68% after electrochemical test under the same condition.

[0111] Comparative Example 7

[0112] The preparation process of the solid-state battery is the same as that of Example 1, except that LiTaO3 is not added in the solid-state electrolyte, and the LiTaO3 is replaced by an equal weight of Li6PS5Cl.

[0113] The discharge capacity is 102 mAh / g and the capacity retention rate is 79% after electrochemical test under the same condition.

[0114] Comparative Example 8

[0115] The preparation process of the solid-state battery is the same as that of Example 1, except that the LiTaO3 in the solid-state electrolyte is replaced by an equal weight of Ta2O5.

[0116] The discharge capacity is 100 mAh / g and the capacity retention rate is 78% after electrochemical test under the same condition.

[0117] The examples and comparative examples show that, compared with the prior art, the capacity and its retention rate of the all-solid-state lithium ion battery described in the present application are significantly improved.

[0118] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the appended claims are intended to cover all such modifications that do not depart from the true spirit and scope of the application. Therefore, the application is not limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A full solid-state lithium ion battery, characterized in that: sequentially comprising a modified silicon-based negative electrode layer, a solid-state electrolyte layer, and a modified positive electrode layer; the modified silicon-based negative electrode layer is obtained by uniformly mixing modified silicon-based particles, a conductive agent, and a binder and then rolling, wherein the modified silicon-based particles are composed of silicon-based particles and a low-voltage-resistant ceramic electrolyte layer coated on the surface of the silicon-based particles, and the thickness of the modified silicon-based negative electrode layer is 20-100 microns; the silicon-based particles are obtained by mixing one of silicon or silicon monoxide and graphite, and then coating carbon on the surface of the mixed particles; the weight ratio of the low-voltage-resistant ceramic electrolyte to the silicon-based particles is (1-2):100; the weight ratio of the modified silicon-based particles, the conductive agent, and the binder is (92-95):(2-3):(3-5); the solid-state electrolyte layer comprises a ceramic electrolyte, a piezoelectric material, and a polymer binder, which are uniformly mixed and then rolled to obtain the solid-state electrolyte layer; the modified positive electrode layer is obtained by uniformly mixing modified positive electrode active particles, a conductive agent, a binder, and a ceramic electrolyte and then rolling, wherein the modified positive electrode active particles are composed of positive electrode active particles and a high-voltage-resistant ceramic electrolyte coated on the surface of the positive electrode active particles; the coating on the surface of the silicon-based particles and the surface of the positive electrode active particles is performed by a mechanical fusion method, and after the mechanical fusion, heat treatment is performed in an inert atmosphere, the heat treatment time is 0.5-2 hours, and the heat treatment temperature is 200-400℃. 2.The full solid-state lithium ion battery of claim 1, characterized in that: the conductive agent in the modified silicon-based negative electrode layer is selected from at least one of acetylene black, nanometer carbon tube, graphene, and carbon fiber. 3.The full solid-state lithium ion battery of claim 1, characterized in that: the weight percentage content of the ceramic electrolyte in the solid-state electrolyte layer is 95%-98%, the weight percentage content of the piezoelectric material is 0.5%-2%, and the weight percentage content of the binder is 1.5%-3%. The low-voltage-resistant ceramic electrolyte is selected from a garnet-type oxide, and the garnet-type oxide has a general structure of Li 7-x La3Zr 2-x M x O 12 , wherein M is selected from at least one of Nb or Ta, and 0.1≤x≤0.

7. 4.The full solid-state lithium ion battery of claim 3, characterized in that: 5.The full solid-state lithium ion battery of claim 3, characterized in that: the piezoelectric material is selected from one or a combination of LiTaO 3, LiNbO 3, NaNbO 3, and NaTaO 3. 6.The full solid-state lithium ion battery of claim 3, characterized in that: the thickness of the modified positive electrode layer is 50-200 microns; the weight ratio of the high-voltage-resistant ceramic electrolyte to the positive electrode active particles is (1-2):100; the weight ratio of the modified positive electrode active particles, the conductive agent, the binder, and the ceramic electrolyte is (93-98):(0.5-2):(1-2):(0.5-3); and the thickness of the solid-state electrolyte layer is 10-100 microns. 7.The full solid-state lithium ion battery of claim 3, characterized in that: the positive electrode active particles are selected from at least one of lithium cobaltate, lithium manganate, lithium nickel manganate, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, a nickel cobalt manganese ternary material, a nickel cobalt aluminum ternary material, and a lithium-rich layered material. ​ The high pressure resistant ceramic electrolyte is selected from a NASICON type oxide, or a metal halide; the NASICON type oxide has a general structure of Li 1+z Al z N 2-z (PO4)3, wherein N is at least one selected from Ti, Ge or Zr, and 0.2≤z≤0.6; the metal halide has a general structure of Li3ZA6, wherein Z is at least one selected from Y, Sc, Er, In, and A is at least one selected from F, Cl, Br or I. ​ ​ ​ ​ ​ ​ The ceramic electrolyte in the solid-state electrolyte layer is a sulfide selected from one or more combinations of Li6PS5C1, Li3PS4, Li7P3S 11 , Li4SnS4, Li 10 GeP2S 12 and derivatives thereof. ​ ​ ​ ​ The ceramic electrolyte in the modified cathode layer is a sulfide selected from one or more combinations of Li6PS5C1, Li3PS4, Li7P3S 11 , Li4SnS4, Li 10 GeP2S 12 and derivatives thereof; ​ ​ ​ ​ ​ 8.The all-solid-state lithium ion battery of claim 1, 3 or 6, wherein: The binder used in the modified silicon-based negative electrode layer, the solid-state electrolyte layer or the positive electrode layer is a fluorinated polyolefin selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene copolymer, and polyperfluoroethylene propylene.

9. A method of producing an all-solid-state lithium-ion battery as claimed in any one of claims 1 to 8, characterized in that The method comprises the following steps: 1) uniformly mixing the silicon-based negative electrode and the low-voltage-resistant ceramic electrolyte at a weight ratio of 100: (1-2), uniformly, completely and conformally coating the low-voltage-resistant ceramic electrolyte on the surface of the silicon-based negative electrode particles by mechanical fusion to obtain modified silicon-based negative electrode particles, and uniformly mixing the modified silicon-based particles, the conductive agent and the binder at a weight ratio of (92-95) : (2-3) : (3-5), and rolling to obtain a modified silicon-based negative electrode layer; 2) uniformly mixing the positive electrode active particles and the high-voltage-resistant ceramic electrolyte at a weight ratio of 100: (1-2), uniformly, completely and conformally coating the high-voltage-resistant ceramic electrolyte on the surface of the positive electrode active particles by mechanical fusion to obtain modified positive electrode active particles, and uniformly mixing the modified positive electrode active particles, the conductive agent, the binder and the ceramic electrolyte at a weight ratio of (93-98) : (0.5-2) : (1-2) : (0.5-3), and rolling to obtain a modified positive electrode layer; 3) uniformly mixing the ceramic electrolyte, the polymer binder and the piezoelectric material at a weight ratio of (95-98) : (0.5-2) : (1.5-3), and rolling to obtain a solid-state electrolyte layer; 4) stacking the modified silicon-based negative electrode layer, the solid-state electrolyte layer and the modified positive electrode layer, and rolling and packaging to assemble an all-solid-state lithium ion battery. 10.The method of claim 9, wherein: The mechanical fusion time in steps 1) and 2) is 0.5-5 hours, and the fusion atmosphere is nitrogen, argon or helium.

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