Solid-state electrolyte and applications thereof

Abstract

The application provides a solid-state electrolyte and application thereof, and the solid-state electrolyte at least comprises: a core body comprising a sulfide electrolyte; and a shell layer wrapped on the surface of the core body, and the shell layer comprises lithium iodide and lithium fluoride. Through the solid-state electrolyte and application thereof, the stability of the solid-state electrolyte to air and positive and negative electrodes can be improved, so that the cycle life and stability of the battery are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a solid-state electrolyte and application thereof. BACKGROUND

[0002] Sulfide electrolytes have high ionic conductivity, wide electrochemical window and good mechanical properties, and are considered as one of the most commercially potential solid-state electrolytes, and are widely used in all-solid-state batteries. However, in practical applications, the sulfide electrolyte has poor stability to air and positive and negative electrodes, thereby affecting the cycle life and stability of the all-solid-state battery, and seriously restricting the further development and application of the battery. SUMMARY

[0003] The present application provides a solid-state electrolyte and application thereof, which can improve the stability of the solid-state electrolyte to air and positive and negative electrodes, thereby improving the cycle life and stability of the battery.

[0004] To solve the above technical problems, the present application provides a solid-state electrolyte, which at least comprises:

[0005] a core comprising a sulfide electrolyte; and

[0006] a shell layer coated on the surface of the core, and the shell layer comprises lithium iodide and lithium fluoride.

[0007] In an embodiment of the present application, the chemical formula of the sulfide electrolyte is Li a P 1-b M b S c O d X e , wherein 5

[0008] In an embodiment of the present application, M is selected from at least one of Sb, In or Bi, and X is Cl, and the value range of b is 0

[0009] In an embodiment of the present application, the chemical formula of the sulfide electrolyte is Li f P 1-g E g S w O g Q zwherein 5 < f < 10, 0 < g < 1, 3 < w < 6, 4 < w + g < 6, 0 < z < 2, E is selected from at least one of Mg, Ca, Sr, Ba, Zn, Cr, Sn or Pb, and Q is selected from at least one of Cl, Br or I.

[0010] In an embodiment of the present application, E is Mg, Q is Cl, and g is in the range of 0.01 ≤ g ≤ 0.1.

[0011] In an embodiment of the present application, the mass ratio of the lithium iodide to the lithium fluoride in the shell layer is (1-10):1.

[0012] In an embodiment of the present application, the thickness of the shell layer is in the range of 1 nm to 100 nm.

[0013] In an embodiment of the present application, the solid-state electrolyte has a retention rate of ion conductivity in the range of 55% to 96% after being exposed to humid air at a dew point temperature of -40° for 24 hours.

[0014] The present application also provides a full solid-state battery, which at least comprises:

[0015] a positive electrode sheet;

[0016] a negative electrode sheet; and

[0017] a solid-state electrolyte film arranged between the positive electrode sheet and the negative electrode sheet, and the solid-state electrolyte film comprises the solid-state electrolyte as described above.

[0018] The present application also provides an electronic device comprising the full solid-state battery as described above.

[0019] In summary, the present application provides a solid-state electrolyte and its application. By improving the solid-state electrolyte in the full solid-state battery, a shell layer is coated on the surface of the core, which can effectively prevent the transmission of electrons between the core and the positive and negative electrode materials, avoid the interface reaction between the core and the positive and negative electrode materials, improve the stability of the solid-state electrolyte to the positive and negative electrodes, and thus improve the cycle life and stability of the full solid-state battery. The shell layer can also prevent the core from directly contacting with the moisture and oxygen in the air, avoid the reaction between the core and the moisture and oxygen in the air, improve the stability of the solid-state electrolyte to the air, and thus further improve the cycle life of the battery. Moreover, the lithium iodide in the shell layer can effectively improve the ion transmission capacity of the solid-state electrolyte, enhance the electrochemical performance of the solid-state electrolyte, and at the same time improve the wettability between the solid-state electrolyte and the positive and negative electrode materials, promote the transmission of ions at the interface between the solid-state electrolyte and the positive and negative electrode materials, and improve the stability of the interface. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to make the technical solutions of the embodiments of the present application clearer, the following will briefly introduce the drawings needed to be used in the description of the embodiments. Obviously, the drawings described in the following description are only some embodiments of the present application, and all other drawings obtained by those skilled in the art without creative effort based on the embodiments of the present application shall fall within the scope of the present application.

[0021] Figure 1 A result graph of a normal temperature cycle performance test on the all-solid-state battery in Embodiment 3 of the present application. DETAILED DESCRIPTION

[0022] The present application will be described in greater detail by way of specific embodiments, from which the skilled person will readily appreciate other advantages and utility of the present application from the disclosure herein. The present application can also be implemented or applied in other different specific embodiments, and the details in the description can be modified or changed based on different views and applications without departing from the spirit of the present application.

[0023] It should be understood that the present application can be implemented in different forms and should not be interpreted as being limited to the embodiments presented herein. On the contrary, these embodiments are presented in order to make the disclosure complete and full, and to fully convey the scope of the present application to those skilled in the art.

[0024] The technical solutions of the present application will be further described in detail below in conjunction with the embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort shall fall within the scope of the present application.

[0025] The present application provides a solid-state electrolyte, for example, comprising a core and a shell. The core comprises a sulfide electrolyte, and the shell is coated on the surface of the core and comprises lithium iodide and lithium fluoride. In the solid-state electrolyte provided by the present application, by arranging the shell, the transmission of electrons between the core and the positive and negative electrode materials can be effectively prevented, the interface reaction between the core and the positive and negative electrode materials can be avoided, the stability of the solid-state electrolyte to the positive and negative electrodes can be improved, and thus the cycle life and stability of the all-solid-state battery can be improved. Moreover, the shell can prevent the core from directly contacting moisture and oxygen in the air, avoid the reaction between the core and the moisture and oxygen in the air, improve the stability of the solid-state electrolyte to the air, and thus further improve the cycle life of the battery.

[0026] In an embodiment of the present application, in the core, the sulfide electrolyte can improve the interface stability between the solid-state electrolyte and the negative electrode, ensure a continuous and stable lithium ion transmission channel, reduce the interface impedance, and improve the charge transmission efficiency. Specifically, the chemical formula of the sulfide electrolyte is, for example, selected from Lia P 1-b M b S c O d X e or Li f P 1-g E g S w O g Q z wherein, in Li a P 1-b M b S c O d X e , 5 < a < 6, 0 < b < 1, 1.5 < c < 5, 0 < d < 2.5, 4 < c + d < 5, 1 < e < 2, M is selected from at least one of Al, Ga, In, Ti, Sc, As, Sb, Bi, V or Nb, and X is selected from at least one of Cl, Br or I. Further, M is for example selected from at least one of Sb, In or Bi, and X is Cl, and b is for example in the range of 0 < b ≤ 0.1, more specifically, b is for example 0.04 when M is for example a +5 valence element, and b is for example 0.02 when M is for example a +3 valence element. By controlling the type of M and X elements in the sulfide electrolyte, and the range of b, the stability of the solid-state electrolyte and the cycle performance of the battery can be improved, and thus the service life of the battery can be prolonged.

[0027] In an embodiment of the present application, when the chemical formula of the sulfide electrolyte is Li f P 1-g E g S w O g Q z , wherein, 5 < f < 10, 0 < g < 1, 3 < w < 6, 4 < w + g < 6, 0 < z < 2, E is for example selected from at least one of Mg, Ca, Sr, Ba, Zn, Cr, Sn or Pb, and Q is for example selected from at least one of Cl, Br or I. Further, E is for example Mg, Q is for example Cl, and g is for example in the range of 0.01 ≤ g ≤ 0.1, more specifically, g is for example 0.02. By controlling the type of E element in the sulfide electrolyte, the type of Q element and the range of g, the stability of the solid-state electrolyte and the cycle performance of the battery can be improved, and thus the service life of the battery can be prolonged.

[0028] In an embodiment of the present application, the lithium iodide in the shell layer has high ionic conductivity, which can effectively improve the ion transmission capacity of the solid-state electrolyte and enhance the electrochemical performance of the solid-state electrolyte. Moreover, the lithium iodide can improve the wettability between the solid-state electrolyte and the positive and negative electrode materials, promote the ion transmission at the interface between the solid-state electrolyte and the positive and negative electrode materials, and improve the stability of the interface.

[0029] In an embodiment of the present application, the lithium fluoride in the shell layer has extremely low electronic conductivity, high chemical inertness and high interface energy, which can form a stable protective layer on the surface of the core. On the one hand, the protective layer can effectively prevent the transmission of electrons between the core and the positive and negative electrode materials, avoid the interface reaction between the core and the positive and negative electrode materials, improve the stability of the solid-state electrolyte to the positive and negative electrode materials, and thus improve the cycle life and stability of the all-solid-state battery. On the other hand, the protective layer can prevent the direct contact between the core and the moisture and oxygen in the air, avoid the reaction between the core and the moisture and oxygen in the air, improve the stability of the solid-state electrolyte to the air, and thus further improve the cycle life of the battery.

[0030] In an embodiment of the present application, the mass ratio of the lithium iodide and the lithium fluoride in the shell layer is, for example, (1-10):1. The lithium fluoride has good chemical stability but poor conductivity. By controlling the mass ratio of the lithium iodide and the lithium fluoride in the shell layer, the stability of the solid-state electrolyte to the air can be improved, and at the same time, the problem of the decrease in the conductivity of the solid-state electrolyte caused by the excessive content of the lithium fluoride can be avoided, thereby improving the cycle performance of the battery.

[0031] In an embodiment of the present application, the thickness of the shell layer is, for example, 1 nm-100 nm, and the ion conductivity retention rate of the solid-state electrolyte after being exposed to the wet air at the dew point temperature of-40° for 24 h is, for example, 55%-96%. By controlling the thickness of the shell layer, the stability of the solid-state electrolyte to the air and the positive and negative electrode materials can be improved, and at the same time, the problem of the decrease in the conductivity of the solid-state electrolyte caused by the excessive thickness of the shell layer can be avoided, thereby improving the cycle performance of the battery.

[0032] In an embodiment of the present application, when the solid-state electrolyte is prepared, first, the core is prepared in an inert gas atmosphere such as argon gas according to the chemical formula Li a P 1-b M b S c O d X e or Li f P 1-g E g S w O g Q zThe Li source, the P source, the M source, the S source and the X source, or the Li source, the P source, the E source, the S source and the Q source are mixed according to a stoichiometric ratio, for example, placed in a ball milling tank for ball milling treatment, to obtain a precursor powder, and then the precursor powder is annealed and sintered at a high temperature to obtain the core material. The Li source is for example selected from at least one of Li2S, LiCl, LiBr or lithium iodide, the P source is for example P2S5, the M source is for example an oxide of M, the S source is for example at least one of the Li source or the P source, the X source is for example from the Li source, the E source is for example an oxide of E, the Q source is for example from the Li source, the mass ratio of the ball to the material is for example (1-100):1, the ball milling time is for example 1h-48h, the rotating speed is for example 50rpm-1500rpm, the sintering temperature is for example 400℃-600℃, and the sintering time is for example 1h-48h.

[0033] In an embodiment of the present application, after obtaining the core, the core, the fluorine-containing compound and the iodine-containing compound are mixed uniformly, for example, placed in a sealed quartz bottle or a polytetrafluoroethylene bottle for heat treatment, the iodine-containing compound and the fluorine-containing compound each react with lithium in the core to generate lithium iodide and lithium fluoride coated on the surface of the core, and a solid-state electrolyte is obtained after cooling. The fluorine-containing compound is selected from at least one of lithium hexafluorophosphate, ammonium hydrogen fluoride or ammonium fluoride, and the iodine-containing compound is selected from at least one of I2 or ammonium iodide, the mass ratio of the fluorine-containing compound to the core is for example 1:(1-100), the mass ratio of the iodine-containing compound to the core is for example 1:(1-100), the heat treatment temperature is for example 30℃-250℃, and the heat treatment time is for example 1h-24h. In this embodiment, the core, the fluorine-containing compound and the iodine-containing compound are mixed and then heat treated, which can quickly construct a shell structure on the surface of the core, thereby improving the preparation efficiency of the solid-state electrolyte, simplifying the preparation method of the solid-state electrolyte and reducing the preparation cost.

[0034] The present application also provides a full solid-state battery, for example, comprising a positive electrode sheet, a negative electrode sheet and a solid-state electrolyte film. The solid-state electrolyte film is arranged between the positive electrode sheet and the negative electrode sheet, and the solid-state electrolyte film is for example obtained by cold pressing the above-mentioned solid-state electrolyte under a pressure of 300MPa-400Mpa, and the thickness of the solid-state electrolyte film is for example 100μm-500μm. In the present application, the full solid-state battery is for example a primary battery or a secondary battery, and the secondary battery is for example a soft package battery, a hard shell battery or a cylindrical battery, and the present application does not specifically limit the type and category of the full solid-state battery.

[0035] In one embodiment of the present application, the positive electrode tab includes, for example, a positive electrode active layer including, for example, a positive electrode active material, a positive electrode electrolyte, a conductive agent, and a binder, etc. In this regard, the present application does not limit the mass ratio of the positive electrode active material, the positive electrode electrolyte, the conductive agent, and the binder, which can be selected as necessary. In other embodiments of the present application, the positive electrode tab can include, in addition to the positive electrode active layer, a positive electrode current collector having the positive electrode active layer coated on at least one side of the surface thereof. In this regard, the positive electrode current collector is, for example, a foil formed by surface treatment of nickel, titanium, aluminum, silver, stainless steel, or carbon, and the positive electrode current collector can be used in any one or a combination of multiple forms such as a film, a mesh, a porous material, a foam, or a non-woven fabric, in addition to the foil.

[0036] In one embodiment of the present application, in the positive electrode active layer, the positive electrode active material is, for example, at least one selected from lithium nickel cobalt manganese oxide (NCM), lithium nickel oxide (LNO), lithium manganese oxide (LMO), lithium nickel manganese oxide (LNMO), lithium cobalt oxide (LCO), or lithium nickel cobalt aluminum oxide (NCA), etc., the positive electrode electrolyte is, for example, a halide solid-state electrolyte, the conductive agent is, for example, at least one selected from graphite, graphene, conductive carbon black (Super P), nano carbon fiber (Vapor-grown carbon fiber, VGCF), or carbon nanotube, etc., and the binder is, for example, at least one selected from polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), polymerized styrene butadiene rubber (SBR), polyvinyl pyrrolidone (PVP), polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), polyacrylic acid (PAA), polyurethane, polyvinyl alcohol (PVA), sodium alginate (Alg), ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, β-cyclodextrin polymer (β-CDp), polypropylene emulsion (LA132), polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), polyfluoroalkoxy (PFA), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polyvinylidene fluoride-hexafluoropropylene copolymer, or polyvinylidene fluoride-trifluorochloroethylene copolymer, etc.

[0037] In one embodiment of the present application, the positive electrode active material is, for example, LiNi 0.8 Co 0.1 Mn 0.1 O2, the positive electrode electrolyte is, for example, Li 2.35 Zr0.65 Fe 0.35 Cl, Br 0.5 I 0.5 The conductive agent, for example, includes Super P and VGCF, and the mass ratio of Super P and VGCF is, for example, 1:1, and the binder is, for example, PTFE. After the positive active material, the positive electrolyte, the conductive agent and the binder are mixed uniformly, for example, in a mass ratio of 69:29:1:1, the positive electrode sheet is obtained directly by dry pressing.

[0038] In another embodiment of the present application, the positive current collector is, for example, an aluminum foil, the positive active material is, for example, LiNi 0.8 Co 0.1 Mn 0.1 O2, the positive electrolyte is, for example, Li 2.35 Zr 0.65 Fe 0.35 Cl, Br 0.5 I 0.5 The conductive agent, for example, includes Super P and VGCF, and the mass ratio of Super P and VGCF is, for example, 1:1, and the binder is, for example, PTFE. After the positive active material, the positive electrolyte, the conductive agent and the binder are mixed uniformly, for example, in a mass ratio of 69:29:1:1, the positive electrode sheet is obtained directly by dry pressing.

[0039] In an embodiment of the present application, the negative electrode sheet is selected from at least one of a metal lithium sheet, a metal indium sheet or a lithium-indium alloy sheet. In other embodiments of the present application, the negative electrode sheet includes a negative current collector and at least a negative active layer coated on one side surface of the negative current collector. The negative current collector is, for example, a copper foil current collector, a composite copper foil current collector, a carbon current collector, a foamed copper current collector or a stainless steel current collector, and the negative active layer includes, for example, a negative active material, a negative electrolyte, a conductive agent and a binder. The present application does not limit the mass ratio of the negative active material, the negative electrolyte, the conductive agent and the binder, which can be selected according to actual needs.

[0040] In an embodiment of the present application, the negative active material is selected from at least one of a graphite material or a silicon material, the negative electrolyte is, for example, a sulfide solid-state electrolyte, the conductive agent is selected from at least one of graphite, graphene, Super P, VGCF or a carbon nanotube, and the binder is selected from at least one of PVDF, CMC, SBR, PVP, PMMA, PAN, PAA, polyurethane, PVA, Alg, ethylene-propylene-diene monomer, styrene-butadiene rubber, fluoro rubber, β-CDp, LA132, PTFE, ETFE, FEP, PFA, PCTFE, ECTFE, polyvinylidene fluoride-hexafluoropropylene copolymer or polyvinylidene fluoride-trifluorochloroethylene copolymer.

[0041] In an embodiment of the present application, the negative current collector is, for example, a copper foil current collector, the negative active material is, for example, silicon, the negative electrolyte is, for example, a sulfide solid-state electrolyte, the conductive agent is, for example, Super P, and the binder is, for example, PTFE. After the negative active material, the negative electrolyte, the conductive agent and the binder are mixed uniformly, for example, in a mass ratio of 72:20:5:3, the mixture is rolled to cover the surface of the copper foil current collector to obtain a negative electrode sheet.

[0042] In an embodiment of the present application, the positive electrode sheet, the solid-state electrolyte film and the negative electrode sheet are sequentially laminated, packaged, hot-pressed and cold-pressed to assemble a full solid-state battery. The assembly process of the full solid-state battery is completed in a glove box in an inert atmosphere.

[0043] Hereinafter, the present application will be explained more specifically by referring to the examples, which should not be understood as limiting. Suitable modifications can be made within the scope consistent with the gist of the present application, which all fall within the technical scope of the present application.

[0044] Example 1

[0045] Preparation of the core: 2 mol of Li2S, 1.5 mol of LiCl, 0.48 mol of P2S5 and 0.02 mol of Sb2O5 were added to a ball mill pot for high-energy ball milling under an argon atmosphere, wherein the ball-to-material ratio was 30:1, the rotation speed was 500 rpm, and the ball milling time was 20 h. After the ball milling, the precursor powder was sintered at 500°C for 10 h to obtain Li 5.5 P 0.96 Sb 0.04 S 4.40 O 0.10 Cl 1.5 sulfide electrolyte.

[0046] Preparation of the solid-state electrolyte: Li 5.5 P 0.96 Sb 0.04 S 4.40 O 0.10 Cl 1.5 sulfide electrolyte, ammonium bifluoride and I2 were mixed uniformly, poured into a sealed polytetrafluoroethylene bottle, and then heat-treated at 250°C for 6 h to obtain the solid-state electrolyte after cooling. The mass ratio of the sulfide electrolyte, ammonium bifluoride and I2 was 100:1:1.

[0047] Preparation of the solid-state electrolyte film: the solid-state electrolyte was cold-pressed at 350 MPa to obtain a solid-state electrolyte film of 300 μm.

[0048] Preparation of the positive electrode sheet: LiNi 0.8 Co0.1 Mn 0.1 O2 positive electrode active material, Li 2.35 Zr 0.65 Fe 0.35 Cl, Br 0.5 I 0.5 The positive electrode electrolyte, the conductive agent and the PTFE are mixed uniformly, for example, in a mass ratio of 69:29:1:1, and then a positive electrode sheet is obtained by dry pressing, and is cut into a circular sheet with a diameter of 10 mm. The conductive agent includes Super P and VGCF, and the mass ratio of Super P and VGCF is, for example, 1:1.

[0049] Selection of the negative electrode sheet: metal lithium is selected as the negative electrode sheet.

[0050] Preparation of the battery: the positive electrode sheet, the solid electrolyte film and the negative electrode sheet are sequentially subjected to processes such as lamination, packaging, hot pressing and cold pressing, to assemble a full solid-state battery.

[0051] Example 2

[0052] The difference between this example and Example 1 is that the mass ratio of the sulfide electrolyte, ammonium bifluoride and I2 is 100:2:2.

[0053] Example 3

[0054] The difference between this example and Example 1 is that the mass ratio of the sulfide electrolyte, ammonium bifluoride and I2 is 100:3:3.

[0055] Example 4

[0056] The difference between this example and Example 1 is that the mass ratio of the sulfide electrolyte, ammonium bifluoride and I2 is 100:10:10.

[0057] Example 5

[0058] The difference between this example and Example 1 is that the mass ratio of the sulfide electrolyte, ammonium bifluoride and I2 is 100:20:20.

[0059] Example 6

[0060] The difference between this example and Example 1 is that the mass ratio of the sulfide electrolyte, ammonium bifluoride and I2 is 100:1:5.

[0061] Example 7

[0062] The difference between this example and Example 1 is that the mass ratio of the sulfide electrolyte, ammonium bifluoride and I2 is 100:2:4.

[0063] Example 8

[0064] This example differs from Example 1 in that the mass ratio of the sulfide electrolyte, ammonium hydrogen fluoride, and I2 is 100:4:2.

[0065] Example 9

[0066] This example differs from Example 1 in that the mass ratio of the sulfide electrolyte, ammonium hydrogen fluoride, and I2 is 100:5:1.

[0067] Example 10

[0068] This example differs from Example 3 in that the fluorine-containing compound in the process of preparing the solid electrolyte is ammonium fluoride, and the mass ratio of the sulfide electrolyte, ammonium fluoride, and I2 is 100:3:3.

[0069] Example 11

[0070] This example differs from Example 3 in that the iodine-containing compound in the process of preparing the solid electrolyte is ammonium iodide, and the mass ratio of the sulfide electrolyte, ammonium hydrogen fluoride, and ammonium iodide is 100:3:3.

[0071] Example 12

[0072] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.5 P 0.99 Sb 0.0 1S 4.475 O 0.025 Cl 1.5 , and the raw materials are 2 mol of Li2S, 1.5 mol of LiCl, 0.495 mol of P2S5, and 0.05 mol of Sb2O5.

[0073] Example 13

[0074] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.5 P 0.94 Sb 0.06 S 4.35 O 0.15 Cl 1.5 , and the raw materials are 2 mol of Li2S, 1.5 mol of LiCl, 0.47 mol of P2S5, and 0.03 mol of Sb2O5.

[0075] Example 14

[0076] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.5 P 0.9 Sb 0.1 S 4.25 O0.25 Cl 1.5 The starting materials were 2 mol of Li2S, 1.5 mol of LiCl, 0.45 mol of P2S5, and 0.05 mol of Sb2O5.

[0077] Example 15

[0078] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.5 P 0.96 Sb 0.0 4S 4.40 O 0.10 Cl 1.3 Br 0.1 I 0.1 The starting materials were 2 mol of Li2S, 1.3 mol of LiCl, 0.1 mol of LiBr, 0.1 mol of lithium iodide, 0.48 mol of P2S5, and 0.02 mol of Sb2O5.

[0079] Example 16

[0080] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.52 P 0.99 In 0.0 1S 4.485 O 0.015 Cl 1.5 The starting materials were 2.01 mol of Li2S, 1.5 mol of LiCl, 0.495 mol of P2S5, and 0.005 mol of In2O3.

[0081] Example 17

[0082] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.54 P 0.98 In 0.0 2S 4.47 O 0.03 Cl 1.5 The starting materials were 2.02 mol of Li2S, 1.5 mol of LiCl, 0.49 mol of P2S5, and 0.01 mol of In2O3.

[0083] Example 18

[0084] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.62 P 0.94 In 0.0 6S 4.41 O 0.09 Cl 1.5Li2.1S1.5P0.45Cl0.05In0.03

[0085] Example 19

[0086] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.7 P 0.9 In 0.1 S 4.35 O 0.15 Cl 1.5 , starting with 2.1 mol of Li2S, 1.5 mol of LiCl, 0.45 mol of P2S5, and 0.05 mol of In2O3.

[0087] Example 20

[0088] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.54 P 0.98 In 0.0 2S 4.47 O 0.03 Cl 1.3 Br 0.1 I 0.1 , starting with 2.02 mol of Li2S, 1.3 mol of LiCl, 0.1 mol of LiBr, 0.1 mol of lithium iodide, 0.49 mol of P2S5, and 0.01 mol of In2O3.

[0089] Example 21

[0090] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.52 P 0.99 Bi 0.0 1S 4.485 O 0.015 Cl 1.5 , starting with 2.01 mol of Li2S, 1.5 mol of LiCl, 0.495 mol of P2S5, and 0.005 mol of Bi2O3.

[0091] Example 22

[0092] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.54 P 0.98 Bi 0.0 2S 4.47 O 0.03 Cl 1.5, starting materials were 2.02 mol of Li2S, 1.5 mol of LiCl, 0.49 mol of P2S5, and 0.01 mol of Bi2O3.

[0093] Example 23

[0094] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.62 P 0.94 Bi 0.0 6S 4.41 O 0.09 Cl 1.5 , starting materials were 2.06 mol of Li2S, 1.5 mol of LiCl, 0.47 mol of P2S5, and 0.03 mol of Bi2O3.

[0095] Example 24

[0096] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.7 P 0.9 Bi 0.1 S 4.35 O 0.15 Cl 1.5 , starting materials were 2.1 mol of Li2S, 1.5 mol of LiCl, 0.45 mol of P2S5, and 0.05 mol of Bi2O3.

[0097] Example 25

[0098] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.54 P 0.98 Bi 0.0 2S 4.47 O 0.03 Cl 1.3 Br 0.1 I 0.1 , starting materials were 2.02 mol of Li2S, 1.3 mol of LiCl, 0.1 mol of LiBr, 0.1 mol of lithium iodide, 0.49 mol of P2S5, and 0.01 mol of Bi2O3.

[0099] Example 26

[0100] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.53 P 0.99 Mg 0.0 1S 4.49 O 0.01 Cl 1.5, starting materials were 2.03 mol of Li2S, 1.5 mol of LiCl, 0.49 mol of P2S5, and 0.02 mol of MgO.

[0101] Example 27

[0102] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.56 P 0.98 Mg 0.0 2S 4.48 O 0.02 Cl 1.5 , starting materials were 2.03 mol of Li2S, 1.5 mol of LiCl, 0.49 mol of P2S5, and 0.02 mol of MgO.

[0103] Example 28

[0104] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.68 P 0.94 Mg 0.0 6S 4.44 O 0.06 Cl 1.5 , starting materials were 2.09 mol of Li2S, 1.5 mol of LiCl, 0.47 mol of P2S5, and 0.06 mol of MgO.

[0105] Example 29

[0106] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.8 P 0.9 Mg 0.1 S 4.48 O 0.1 Cl 1.5 , starting materials were 2.15 mol of Li2S, 1.5 mol of LiCl, 0.45 mol of P2S5, and 0.1 mol of MgO.

[0107] Example 30

[0108] This example differs from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.56 P 0.98 Mg 0.0 2S 4.48 O 0.02 Cl 1.3 Br 0.1 I 0.1, raw materials were 2.03 mol of Li2S, 1.3 mol of LiCl, 0.1 mol of LiBr, 0.1 mol of lithium iodide, 0.49 mol of P2S5, and 0.02 mol of MgO.

[0109] Comparative Example 1

[0110] This comparative example is different from Example 3 in that the chemical formula of the sulfide electrolyte is Li 5.5 PS 4.5 Cl 1.5 , raw materials were 2 mol of Li2S, 1.5 mol of LiCl, and 0.5 mol of P2S5.

[0111] Comparative Example 2

[0112] This comparative example is different from Example 1 in that the solid-state electrolyte only includes the core.

[0113] Comparative Example 3

[0114] This comparative example is different from Example 1 in that the mass ratio of the sulfide electrolyte, ammonium hydrogen fluoride, and I2 is 100:150:150.

[0115] The compositions and parameters of the core and the shell layer in the solid-state electrolytes of each example and comparative example are shown in Table 1. Moreover, in an embodiment of the present application, for example, the stability of the solid-state electrolytes in air in each example and comparative example is tested, and the test results are shown in Table 1. Specifically, the ion conductivities of the solid-state electrolytes before and after exposure to humid air with a dew point temperature of -40° for 24 h are measured respectively, and then the retention rate of the ion conductivity after exposure for 24 h is calculated.

[0116] Table 1, parameters of the solid-state electrolytes in Examples 1-30 and Comparative Examples 1-3

[0117]

[0118]

[0119] In the present application, the full solid-state batteries prepared by using the different solid-state electrolyte films in Examples 1-30 and Comparative Examples 1-3 are tested for performance.

[0120] See Figure 1As shown, in an embodiment of the present application, for example, the full solid-state battery in Example 3 is subjected to a normal temperature cycle performance test. Specifically, at 25°C, the full solid-state battery is subjected to a cycle charge-discharge in a specified voltage interval 2.5V-4.3V at a charge-discharge rate of 1C / 1C, and the capacity (Capacity, CC) and Coulombic efficiency (Coulombic Efficiency, CE) at different cycle numbers are obtained. From the results shown in Table 1, it can be seen that as the cycle number increases, the decay trend of the battery CC is relatively flat, and the CE of the battery does not fluctuate and is stable at about 100%, indicating that the cycle performance of the battery is good. Figure 1

[0121] As shown in Table 2, in an embodiment of the present application, for example, the full solid-state batteries in Examples 1-30 and Comparative Examples 1-3 are subjected to a normal temperature cycle stability test. Specifically, at 25°C, the full solid-state battery is subjected to a cycle charge-discharge in a specified voltage interval 2.5V-4.3V at a charge-discharge rate of 1C / 1C, and when the battery capacity reaches 80% of the first cycle capacity State of Health (SOH), the test is ended, and the normal temperature cycle number of the battery is recorded. The results are shown in Table 2.

[0122] Table 2, Test results of full solid-state batteries in Examples 1-30 and Comparative Examples 1-3

[0123]

[0124]

[0125] As shown in Table 1 and Table 2, it can be seen that as the mass of the fluorine-containing compound and the iodine-containing compound increases, the thickness of the shell layer gradually increases, the retention rate of the ionic conductivity of the solid-state electrolyte gradually increases, i.e., the stability of the solid-state electrolyte to air gradually increases, and the normal temperature cycle number of the battery first gradually increases and then gradually decreases, i.e., the normal temperature cycle stability of the battery presents a trend of first increasing and then decreasing, indicating that the shell layer can improve the electrochemical stability of the solid-state electrolyte and the stability to air, but when the thickness of the shell layer is too large, it will greatly hinder the transmission of lithium ions, resulting in a serious decrease in the conductivity of the solid-state electrolyte, thereby affecting the cycle performance of the battery. Therefore, by controlling the thickness of the shell layer, the stability of the solid-state electrolyte and the cycle performance of the battery can be taken into account.

[0126] ​As shown in Table 1 and Table 2, it can be seen from Comparative Example 3 and Examples 6-9 that, as the mass of the fluorine-containing compound increases, the retention rate of the ionic conductivity of the solid-state electrolyte gradually increases, that is, the stability of the solid-state electrolyte to air gradually increases, and the number of cycles at room temperature of the battery first gradually increases and then gradually decreases, that is, the cycle stability of the battery at room temperature presents a trend of first increasing and then decreasing, thereby indicating that, as the mass of the fluorine-containing compound increases, the content of lithium fluoride in the shell layer is more and more, since lithium fluoride has good chemical stability but poor electrical conductivity, the stability of the solid-state electrolyte to air gradually increases, but the cycle performance of the battery presents a trend of first increasing and then decreasing. Therefore, by controlling the mass of the fluorine-containing compound, the stability of the solid-state electrolyte and the cycle performance of the battery can be taken into account.

[0127] As shown in Table 1 and Table 2, it can be seen from Comparative Example 3, 10 and 11 that, among various combinations of the fluorine-containing compound and the iodine-containing compound, the solid-state electrolyte prepared by combining ammonium bifluoride and I2 has the largest retention rate of ionic conductivity, that is, the solid-state electrolyte has the best stability to air, and the battery obtained by using the combination has the largest number of cycles at room temperature, that is, the battery has the best cycle performance. Therefore, by changing the types of the fluorine-containing compound and the iodine-containing compound, the stability of the solid-state electrolyte and the cycle performance of the battery can be changed.

[0128] As shown in Table 1 and Table 2, it can be seen from Comparative Example 3, 12 to 14 that, as the doping amount of the Sb element in the sulfide electrolyte increases, the retention rate of the ionic conductivity of the solid-state electrolyte gradually increases, that is, the stability of the solid-state electrolyte to air gradually increases, and the number of cycles at room temperature of the battery first gradually increases and then gradually decreases, that is, the cycle performance of the battery presents a trend of first increasing and then decreasing. As shown in Table 1 and Table 2, it can be seen from Comparative Example 16-19 that, as the doping amount of the In element in the sulfide electrolyte increases, the retention rate of the ionic conductivity of the solid-state electrolyte gradually increases, that is, the stability of the solid-state electrolyte to air gradually increases, and the number of cycles at room temperature of the battery first gradually increases and then gradually decreases, that is, the cycle performance of the battery presents a trend of first increasing and then decreasing. As shown in Table 1 and Table 2, it can be seen from Comparative Example 21-24 that, as the doping amount of the Bi element in the sulfide electrolyte increases, the retention rate of the ionic conductivity of the solid-state electrolyte gradually increases, that is, the stability of the solid-state electrolyte to air gradually increases, and the number of cycles at room temperature of the battery first gradually increases and then gradually decreases, that is, the cycle performance of the battery presents a trend of first increasing and then decreasing. Therefore, by controlling the doping amount of the M element in the sulfide electrolyte, the stability of the solid-state electrolyte and the cycle performance of the battery can be taken into account.

[0129] As shown in Table 1 and Table 2, it can be seen from Comparative Examples 26-29 that, as the doping amount of Mg element in the sulfide electrolyte increases, the retention rate of ionic conductivity of the solid-state electrolyte gradually increases, i.e., the stability of the solid-state electrolyte to air gradually increases, and the cycle number of the battery at room temperature first gradually increases and then gradually decreases, i.e., the cycle performance of the battery presents a trend of first improving and then declining. Therefore, by controlling the doping amount of E element in the sulfide electrolyte, the stability of the solid-state electrolyte and the cycle performance of the battery can be considered.

[0130] As shown in Table 1 and Table 2, it can be seen from Comparative Examples 3 and 15, Examples 17 and 20, Examples 22 and 25, and Examples 27 and 30 that, when the doping amount of Sb, In, Bi or Mg element in the sulfide electrolyte is the same, if Br and I elements are doped into the sulfide electrolyte, the retention rate of ionic conductivity of the solid-state electrolyte will decrease, i.e., the stability of the solid-state electrolyte to air decreases, and the cycle number of the battery at room temperature will also decrease, i.e., the cycle performance of the battery decreases. Therefore, by controlling the number of types of elements contained in X or Q in the sulfide electrolyte, the stability of the solid-state electrolyte and the cycle performance of the battery can be further improved.

[0131] As shown in Table 1 and Table 2, it can be seen from Comparative Example 3, Example 17, Example 22, Example 27 and Comparative Example 1 that, when no Sb, Bi, In or Mg element is doped in the sulfide electrolyte, the retention rate of ionic conductivity of the solid-state electrolyte will significantly decrease, i.e., the stability of the solid-state electrolyte to air is very poor, and the cycle number of the battery at room temperature is only 84, almost without cycle performance, thereby indicating that: the Sb, Bi, In or Mg element doped in the sulfide electrolyte can significantly improve the stability of the solid-state electrolyte to air and the cycle performance of the battery. Therefore, by controlling the types of elements of M or E in the electrolyte, the stability of the solid-state electrolyte and the cycle performance of the battery can be improved.

[0132] The application further provides an electronic device comprising at least one all-solid-state battery as described above, the all-solid-state battery being used to provide electric energy. The electronic device can be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool, etc. In an embodiment of the application, the vehicle is, for example, a new energy vehicle, which can be a pure electric vehicle, a hybrid vehicle, or a range-extended vehicle, etc. The spacecraft includes an airplane, a rocket, a space shuttle, a spacecraft, etc. The electric toy includes a fixed or mobile electric toy, such as a game console, an electric vehicle toy, an electric ship toy, an electric airplane toy, etc. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool, and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact electric drill, a concrete vibrator, an electric planer, etc. The electronic device comprises the all-solid-state battery as described above, and thus has the advantages of the all-solid-state battery as described above, which will not be described herein.

[0133] In summary, the application provides a solid-state electrolyte and an application thereof. By coating a shell layer on the surface of the core, on the one hand, the shell layer can effectively prevent the transmission of electrons between the core and the positive and negative electrode materials, avoid the interface reaction between the core and the positive and negative electrode materials, improve the stability of the solid-state electrolyte to the positive and negative electrodes, thereby improving the cycle life and stability of the all-solid-state battery. On the other hand, the shell layer can prevent the core from directly contacting with moisture and oxygen in the air, avoid the reaction between the core and the moisture and oxygen in the air, improve the stability of the solid-state electrolyte to the air, thereby further improving the cycle life of the battery. Moreover, the lithium iodide in the shell layer can effectively improve the ion transmission capacity of the solid-state electrolyte, enhance the electrochemical performance of the solid-state electrolyte, and improve the wettability between the solid-state electrolyte and the positive and negative electrode materials, promote the transmission of ions at the interface between the solid-state electrolyte and the positive and negative electrode materials, and improve the stability of the interface.

[0134] The above description is merely the preferred embodiments of the application and the explanation of the applied technical principles, and those skilled in the art should understand that the application range involved in the application is not limited to the technical solutions formed by the specific combinations of the above technical features, and should also cover other technical solutions formed by any combinations of the above technical features or equivalent features without departing from the inventive concept, such as the technical solutions formed by the mutual replacement of the above features and the technical features disclosed in the application (but not limited to) having similar functions.

[0135] In addition to the technical features described in the specification, the remaining technical features are known to those skilled in the art, and in order to highlight the innovative features of the application, the remaining technical features will not be described here.

Claims

1. A solid state electrolyte, characterized by, At least comprising: Nucleus comprising a sulfide electrolyte of formula Li a P 1-b M b S c O d X e or Li f P 1- g E g S w O g Q z wherein 5 < a < 6, 0 < b < 1, 1.5 < c < 5, 0 < d < 2.5, 4 < c+d < 5, 1 < e < 2, M is selected from at least one of Al, Ga, In, Ti, Sc, As, Sb, Bi, V or Nb, X is selected from at least one of Cl, Br or I, 5 < f < 10, 0 < g < 1, 3 < w < 6, 4 < w+g < 6, 0 < z < 2, E is selected from at least one of Mg, Ca, Sr, Ba, Zn, Cr, Sn or Pb, Q is selected from at least one of Cl, Br or I; and a shell layer coated on the surface of the core, and the shell layer comprises lithium iodide and lithium fluoride, and the mass ratio of the lithium iodide to the lithium fluoride is (1-10):

1.

2. The solid-state electrolyte of claim 1, wherein, M is selected from at least one of Sb, In or Bi, X is Cl, and the value range of b is 0 3. The solid-state electrolyte of claim 1, wherein, E is Mg, Q is Cl, and the value range of g is 0.01 4. The solid-state electrolyte of claim 1, wherein, The thickness of the shell layer is 1-100 nm.

5. The solid-state electrolyte of claim 1, wherein, The retention rate of the ion conductivity of the solid-state electrolyte is 55-96% after the solid-state electrolyte is exposed to humid air with a dew point temperature of -40° for 24 h.

6. An all-solid battery, characterized by, At least comprising: a positive electrode tab; a negative electrode tab; and a solid-state electrolyte film arranged between the positive electrode tab and the negative electrode tab, and the solid-state electrolyte film comprises the solid-state electrolyte according to any one of claims 1-5.

7. An electronic device, comprising: The all-solid-state battery comprises the all-solid-state battery according to claim 6.

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