An integrated composite electrode, a method for manufacturing the same, and a battery

Abstract

The application relates to the technical field of all-solid-state batteries, in particular to an integrated composite electrode, a preparation method thereof and a battery. The preparation method comprises the following steps: electrolyte precursors with a lithium content lower than a target stoichiometric ratio of a sulfide solid electrolyte are weighed, and are mixed with electrode materials, a conductive agent and a binder to obtain a mixture; the mixture is loaded on a current collector and is compacted to obtain a pre-prepared electrode; a lithiation reaction is carried out in a lithium-containing source device to generate lithium sulfide precursors in situ; and sintering is carried out under an inert atmosphere, so that the electrolyte precursors and the lithium sulfide precursors react to generate sulfide solid electrolytes in situ. Through the process of "lithium-deficient precursors + in-situ electrochemical lithium supplement + in-situ sintering", the nanoscale interface fusion of the electrolyte and the electrode material is realized, the solid-solid interface impedance is significantly reduced, and the rate performance and the cycle stability of the battery are improved.

Description

Technical Field

[0001] This invention relates to the field of all-solid-state battery technology, specifically to an integrated composite electrode, its preparation method, and a battery. Background Technology

[0002] With the rapid development of new energy vehicles and portable electronic devices, higher demands are being placed on the energy density and safety of lithium-ion batteries. Traditional liquid lithium-ion batteries are limited by the flammability and electrochemical window of organic electrolytes, posing safety hazards and encountering bottlenecks in energy density improvement. All-solid-state batteries, which use solid electrolytes instead of liquid electrolytes, offer higher safety and a wider electrochemical window, and are considered the development direction for next-generation high-energy-density batteries.

[0003] Among various solid-state electrolytes, sulfide solid-state electrolytes have attracted much attention due to their extremely high ionic conductivity (on the order of 10⁻² S / cm) and good mechanical ductility. However, existing sulfide solid-state battery fabrication processes mostly employ dry or wet processes that involve "first synthesizing electrolyte powder, then mixing and coating it with electrode materials." This traditional process has the following significant drawbacks: Poor interface contact: The pre-formed electrolyte powder and the electrode active material are in point contact, resulting in high solid-solid interface impedance, which seriously affects the rate performance of the battery.

[0004] Complex process: Sulfide electrolytes are sensitive to air, and the synthesis, storage and transportation of powders require strict environmental control, which increases manufacturing costs.

[0005] Structural instability: During charging and discharging, the volume expansion and contraction of electrode materials can easily lead to solid-solid interface separation, resulting in a decrease in battery cycle life.

[0006] Therefore, developing an integrated composite electrode preparation method that can generate sulfide solid electrolytes in situ and achieve nanoscale fusion of electrodes and electrolytes has significant application value. Summary of the Invention

[0007] The purpose of this invention is to provide an integrated composite electrode, its preparation method, and a battery, to solve the problems of high solid-solid interface impedance and complex preparation process in existing solid-state batteries.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing an integrated composite electrode, comprising the following steps: S1. Weigh an electrolyte precursor with a lithium content lower than the theoretical stoichiometric ratio of the target sulfide solid electrolyte according to the component ratio required for preparing the target sulfide solid electrolyte, and mix and grind the electrolyte precursor with electrode material, conductive agent and binder to obtain a mixture.

[0009] S2. The mixture is loaded onto the surface and / or internal pores of the current collector and compacted to obtain a prefabricated electrode.

[0010] S3. The prefabricated electrode is placed in an electrochemical reaction device containing a lithium source to carry out a lithiation reaction, so that the prefabricated electrode generates a lithium sulfide precursor in situ.

[0011] S4. The pre-fabricated electrode after step S3 is placed in an inert atmosphere for sintering treatment, so that the electrolyte precursor in step S1 reacts with the lithium sulfide precursor generated in situ in step S3 to generate a sulfide solid electrolyte in situ. After cooling, the integrated composite electrode is obtained.

[0012] Further, in step S1, when the crystal form of the target sulfide solid electrolyte is silver-germanium sulfide type, the electrolyte precursor is prepared according to the formula corresponding to Li 7-n PS 6-n X n The chemical formula uses the molar ratio of elements from phosphorus source, sulfur source, and halogen source, where X includes at least one of Cl, Br, and I, and 0 <n≤1.8; When the crystal form of the target sulfide solid electrolyte is LGPS, the electrolyte precursor is prepared according to the corresponding Li 11-n M 2- n P 1+n S 12 The chemical formula uses phosphorus, sulfur, germanium, tin, and silicon as source materials, where M includes at least one of Ge, Sn, and Si, and 0. <n≤1.8。

[0013] Further, in step S1, the electrolyte precursor contains a sulfur source, and the amount of sulfur source added is 100.1% to 120% of the theoretical stoichiometric molar amount of the target sulfide solid electrolyte.

[0014] Furthermore, in step S1, the electrolyte precursor contains elemental sulfur as the sulfur source, phosphorus pentasulfide as the phosphorus source, and halogen source selected from at least one of lithium chloride, lithium bromide, and lithium iodide.

[0015] Furthermore, in step S1, the electrode material is selected from one of the following: positive electrode material, negative electrode material, or integrated composite material that combines electrochemical activity and ion / electron conduction function.

[0016] Furthermore, the positive electrode material is at least one of ternary materials, lithium cobalt oxide, lithium iron phosphate, sulfur, and sulfurized polyacrylonitrile, and the negative electrode material is at least one of silicon-based materials, carbon-based materials, tin-based materials, and oxides.

[0017] Furthermore, in step S2, the compaction process adopts a hot pressing process with a pressure of 10MPa to 500MPa, a temperature of 15℃ to 150℃, and a holding time of 0.1min to 30min.

[0018] Further, in step S2, the current collector is selected from at least one of metal foil, conductive thin film material, or porous metal material; Among them, metal foil materials include copper foil, aluminum foil, nickel foil, titanium foil, or stainless steel foil; Conductive thin film materials include carbon fiber paper, porous carbon cloth, or composite current collectors; Porous metallic materials include copper foam, nickel foam, aluminum foam, or metal fiber felt.

[0019] Furthermore, in step S3, the lithium source is a lithium metal sheet or a pre-lithiated material; the electrochemical reaction is carried out at a current density of 0.1 to 10 mA / cm², and the lower limit cutoff voltage relative to the lithium metal reference electrode is 2.0 V.

[0020] Furthermore, in step S4, the sintering temperature is 200℃~400℃, the sintering time is 2h~10h, and the cooling method is furnace cooling or program-controlled cooling.

[0021] The present invention also provides an integrated composite electrode, comprising a current collector and an active composite layer loaded on the surface and / or internal pores of the current collector. The active composite layer comprises an electrode material, a conductive agent, a binder, and a sulfide solid electrolyte. The sulfide solid electrolyte is prepared by reacting an electrolyte precursor with an in-situ generated lithium sulfide precursor, and the sulfide solid electrolyte and the electrode material form a three-dimensional network structure with a nanoscale interface fusion.

[0022] The present invention also provides a battery comprising the above-described integrated composite electrode or an integrated composite electrode prepared by the above-described method for preparing an integrated composite electrode.

[0023] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention relates to an integrated composite electrode preparation method that uses a process of “lithium-deficient precursor + in-situ electrochemical lithium replenishment + in-situ sintering” to enable sulfide solid electrolyte to grow directly on the surface of electrode particles and in the pores of current collector, thereby achieving nanoscale close contact between the electrode and the electrolyte and significantly reducing solid-solid interface impedance.

[0024] 2. The present invention relates to an integrated composite electrode in which an in-situ generated sulfide solid electrolyte forms a continuous and dense three-dimensional ion transport network in the active composite layer, which effectively improves the utilization rate of active materials and improves the rate performance of the battery.

[0025] 3. The integrated composite electrode structure of the present invention is compact, with strong bonding between the electrolyte and the electrode material, which can effectively buffer the volume expansion of the electrode material during charging and discharging, thereby improving the cycle stability of the battery.

[0026] 4. The method for preparing an integrated composite electrode according to the present invention is compatible with existing battery electrode coating and rolling processes, and is easy to achieve large-scale production. Attached Figure Description

[0027] Figure 1 This is a logic diagram of electrode evolution in the integrated composite electrode preparation method of the present invention; Figure 2 XRD patterns of the sulfide solid electrolytes prepared in Examples 1, 2, 12, 53 and Comparative Example 1 of this invention; Figure 3 These are scanning electron microscope (SEM) images of the microstructure of the electrodes prepared in Example 1 and Comparative Example 1 of the present invention. Figure 4 Impedance diagrams of the sulfide solid electrolytes prepared in Examples 1-5 and Comparative Examples 1-2 of this invention; Figure 5 The graph shows the polarization voltage curve of the symmetrical battery assembled with the sulfide solid electrolyte membrane prepared in Example 1. Figure 6 Polarization voltage curve of a symmetrical battery assembled with a sulfide solid electrolyte membrane prepared in Comparative Example 1; Figure 7 The charge-discharge curve of the solid-state battery assembled with the integrated composite electrode prepared in Example 1 of the present invention; Figure 8 The charge-discharge curve of the solid-state battery assembled with the electrode prepared in Comparative Example 1 of this invention; Figure 9 The graph shows the cycle performance test results of the solid-state battery assembled with the integrated composite electrode prepared in Example 1 of this invention. Figure 10 The graph shows the cycle performance test results of the solid-state battery assembled with the electrode prepared in Comparative Example 1 of this invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1: In this embodiment, a sulfide solid electrolyte membrane (electrolyte 1) without positive electrode active material and an integrated composite positive electrode (positive electrode 1) containing positive electrode active material were prepared respectively.

[0030] Among them, the target in-situ generated sulfide solid electrolyte is Li6PS5Cl of the silver-germanium sulfide type (i.e., Li 7-n PS 6-n X n (In the specific form when n=1, X=Cl), the active material is a ternary material (LiNi). 0.8 Mn 0.1 Co 0.1 O2 (NMC811)). The steps are as follows: S1, precursor mixing.

[0031] Based on the stoichiometric ratio of Li6PS5Cl, the required precursor molar ratio is Li2S : P2S5 : LiCl = 2.5 : 0.5 : 1.0. In an argon-filled glove box, elemental sulfur powder (as a sulfur source, 10 mol% excess to compensate for sintering losses), P2S5 powder, and LiCl powder were calculated and weighed according to the aforementioned molar ratio and ball-milled to obtain the precursor blend for electrolyte 1. This blend was then further dry-mixed with NMC811 active material, conductive carbon black (Super P), and PTFE binder at a mass ratio of 15 : 80 : 2 : 3 to obtain the precursor blend for cathode 1.

[0032] S2, Prefabricated electrode construction.

[0033] The precursor blends of electrolyte 1 and positive electrode 1 were uniformly spread on aluminum foil current collectors and hot-pressed at 150 MPa and 80°C for 5 minutes to obtain pre-formed electrodes of electrolyte 1 and positive electrode 1, respectively, with an active material surface loading of approximately 3.0 mAh / cm².

[0034] S3, in-situ reaction and lithiation.

[0035] Using pre-fabricated electrodes of electrolyte 1 and positive electrode 1 as positive electrodes, lithium metal sheets as negative electrodes, and Celgard 2500 as separators, 25 μL of 0.5M LiTFSI / DOM-DME (volume ratio 1:1) electrolyte was injected to assemble CR2032 coin cells. The cells were discharged at a rate of 0.05C to a cutoff voltage of 2.0 V to lithiumize elemental sulfur (S) to Li₂S. The degree of reaction was controlled so that the final molar ratio of Li₂S, P₂S₅, and LiCl in the electrode was approximately 2.0:0.5:1.6.

[0036] S4, sintering.

[0037] After discharging the battery in step S3, the positive electrode sheet is removed, washed with DMC solvent, and then vacuum dried. The electrode sheet is then placed in a tube furnace and sintered at 200°C for 5–15 hours under vacuum or flowing argon protection, followed by furnace cooling. After cooling, electrolyte 1 and the integrated composite positive electrode 1 are obtained.

[0038] Example 2: In this embodiment, an integrated composite positive electrode is prepared, wherein the target in-situ generated sulfide solid electrolyte is Li6PS5Cl. 0.5 Br 0.5 (can be considered as n=1, belonging to Li) 7-n PS 6-n X n (General formula category), the active material is NMC811. The steps are as follows: S1, Precursor Mixture.

[0039] According to the chemical formula Li6PS5Cl 0.5 Br 0.5 The required precursor molar ratio was calculated to be Li₂S : P₂S₅ : LiBr : LiCl = 2.5 : 0.5 : 0.5 : 0.5. In a glove box, elemental sulfur powder (10 mol% excess), P₂S₅ powder, LiBr powder, and LiCl powder were calculated and weighed according to the aforementioned molar ratio as precursors. These were then dry-mixed with NMC811, conductive carbon black (Super P), and PTFE at a mass ratio of 15 : 80 : 2 : 3.

[0040] S2. Prefabricated electrode construction.

[0041] Similar to Example 1, a preformed positive electrode sheet was prepared by hot pressing on an aluminum foil at 200 MPa pressure and 100°C for 3 minutes.

[0042] S3, In-situ reaction and lithiation.

[0043] Assemble the battery, inject 25 μL of electrolyte, and discharge it to 1.8 V at a rate of 0.05C.

[0044] S4, sintering.

[0045] After the lithiated electrode sheet is dried, it is placed under vacuum or argon protection and sintered at 200°C for 5 to 15 hours. The temperature is then controlled by a program to cool it to room temperature, thus obtaining electrolyte 2 and integrated composite positive electrode 2.

[0046] Example 3: This embodiment prepares Li 10 GeP2S 12 For solid electrolytes, ternary materials LiNi 0.8 Co 0.1 Mn0.1 O2 (NCM811) is an integrated composite positive electrode with active material. The steps are as follows: S1, Precursor Mixture.

[0047] In the argon glove box, according to Li 10 GeP2S 12 The stoichiometric ratio was calculated, and elemental sulfur powder (as the sulfur source), P2S5, and GeS2 were weighed as electrolyte precursors and blended by ball milling. The amount of elemental sulfur was increased by an additional 10 mol% to compensate for potential losses.

[0048] Weigh out NCM811 active material, conductive carbon black (Super P) and polytetrafluoroethylene (PTFE) binder, wherein the mass ratio of active material: electrolyte precursor mixture: conductive agent: binder is 80:15:2:3.

[0049] Place all materials in a mixer and dry mix for 2 hours to obtain a uniform mixture.

[0050] S2, Prefabricated electrode construction.

[0051] The mixture is spread on aluminum foil and pre-pressed under 10 MPa pressure, followed by hot pressing at 150°C and 200 MPa pressure for 2 minutes to obtain a pre-fabricated electrode sheet.

[0052] S3, in-situ reaction and lithiation.

[0053] Using this prefabricated electrode as the positive electrode, a lithium metal sheet as the negative electrode, Celgard 2500 as the separator, and 25 μL of 0.5M LiTFSI / DOM-DME (volume ratio 1:1) electrolyte, a CR2032 coin cell was assembled. Discharging to 1.8 V at a rate of 0.05C allowed the elemental sulfur in the positive electrode to completely react and form Li₂S.

[0054] S4, sintering.

[0055] The discharged positive electrode sheet was removed from the battery and vacuum dried at 60°C for 12 hours. It was then placed in a tube furnace and heated to 250°C at a rate of 2°C / min under an argon atmosphere, and held at that temperature for 5–15 hours. Finally, it was cooled to room temperature with the furnace to obtain electrolyte 3 and the integrated composite positive electrode 3.

[0056] Example 4: This embodiment prepares Li 10 SnP2S 12 This is an integrated composite cathode using a solid electrolyte and ternary material NCM811 as the active material. The steps are as follows: S1, precursor mixing.

[0057] According to Li 10 SnP2S 12 The stoichiometric ratios of S, P2S5, and SnS2 are determined by weighing out the materials. The proportions of other materials and the mixing steps are the same as in Example 3.

[0058] S2, Prefabricated electrode construction.

[0059] Same as Example 3.

[0060] S3, in-situ reaction and lithiation.

[0061] Same as Example 3.

[0062] S4, sintering.

[0063] Same as in Example 3, electrolyte 4 and integrated composite positive electrode 4 were obtained.

[0064] Example 5: This embodiment prepares an integrated composite cathode using Li7SiPS8 as the solid electrolyte and NCM811 as the ternary material as the active material. The steps are as follows: S1, precursor mixing.

[0065] Weigh out S, P2S5, and SnS2 according to the stoichiometric ratio of Li7SiPS8. The proportions of other materials and the mixing steps are the same as in Example 3.

[0066] S2. Prefabricated electrode construction.

[0067] Same as Example 3.

[0068] S3, in-situ reaction and lithiation.

[0069] Same as Example 3.

[0070] S4, sintering.

[0071] Same as in Example 3, electrolyte 5 and integrated composite positive electrode 5 were obtained.

[0072] Example 6: This embodiment prepares an integrated composite cathode using Li7PS6 (silver-germanium sulfide type) as the solid electrolyte and NCM811 as the ternary material as the active material. The steps are as follows: S1, precursor mixing.

[0073] Phosphorus pentasulfide (phosphorus pentasulfide) and elemental sulfur (sulfur) were weighed according to the molar ratio of Li7PS6, with no halogen source added; the amount of sulfur source added was 110% of the theoretical molar amount. The electrolyte precursor, NCM811, conductive carbon black, and PTFE binder were mixed evenly by dry ball milling at a mass ratio of 15:80:2:3 to obtain a mixture.

[0074] S2. Preparation of prefabricated electrodes.

[0075] The mixture is loaded onto the surface of an aluminum foil current collector, and a hot pressing process is used: pressure 150MPa, temperature 80℃, and holding pressure for 5min to obtain a pre-fabricated electrode.

[0076] S3, in-situ lithiation reaction.

[0077] A coin cell was assembled using a pre-fabricated electrode as the positive electrode and a lithium metal sheet as the negative electrode, with a current density of 0.5 mA / cm². 2 When discharged to the cutoff voltage of 2V, lithium sulfide precursor is generated in situ inside the electrode.

[0078] S4, inert atmosphere sintering.

[0079] The lithiated electrode was placed in an argon inert atmosphere tube furnace, sintered at 200℃ for 6 hours, and cooled with the furnace after the reaction was completed to obtain an integrated composite cathode.

[0080] Example 7: This embodiment prepares Li 6.1 PS 5.1 Cl 0.9 (Sulphur-germanium ore type, X=Cl) is the solid electrolyte, and the ternary material NCM811 is the integrated composite cathode with active material. The steps are as follows: S1, precursor mixing.

[0081] Phosphorus pentasulfide, elemental sulfur, and lithium chloride were weighed according to the molar ratio of their chemical formulas; the amount of sulfur source added was 110% of the theoretical molar amount. The material ratio and mixing method were consistent with those in Example 6.

[0082] S2 to S4, hot pressing parameters, lithiation conditions, sintering parameters, and post-processing procedures are exactly the same as in Example 6.

[0083] Example 8: This embodiment prepares Li 5.2 PS 4.2 Br 1.8 (Sulphur-germanium ore type, X=Br) is the solid electrolyte, and the ternary material NCM811 is the integrated composite cathode with active material. The steps are as follows: S1, precursor mixing.

[0084] Phosphorus pentasulfide, elemental sulfur, and lithium bromide were weighed according to the molar ratio of their chemical formulas; the amount of sulfur source added was 110% of the theoretical molar amount. The material ratio and mixing method were consistent with those in Example 6.

[0085] S2 to S4: The complete set of process parameters is exactly the same as in Example 6.

[0086] Example 9: This embodiment prepares Li 11 Ge2PS 12 (LGPS type, M=Ge) is a solid electrolyte, and the ternary material NCM811 is an integrated composite cathode with the active material. The steps are as follows: S1, precursor mixing.

[0087] Phosphorus pentasulfide, elemental sulfur, and germanium disulfide were weighed according to the chemical formula molar ratio; the amount of sulfur source added was 110% of the theoretical molar amount, and the material ratio and mixing method were the same as in Example 6.

[0088] S2 to S4, the complete set of process parameters are the same as in Example 6.

[0089] Example 10: This embodiment prepares Li 10.1 Sn 1.1 P 1.9 S 12 (LGPS type, M=Sn) is a solid electrolyte, and the ternary material NCM811 is an integrated composite cathode with active material. The steps are as follows: S1, precursor mixing.

[0090] Weigh out phosphorus pentasulfide, elemental sulfur, and tin disulfide according to their chemical formula molar ratios; the amount of sulfur source added is 110% of the theoretical stoichiometric molar amount.

[0091] S2~S4: The complete set of process parameters is consistent with those in Example 6.

[0092] Example 11: This embodiment prepares Li 9.2 Si 0.2 P 2.8 S 12 (LGPS type, M=Si) is a solid electrolyte, and the ternary material NCM811 is an integrated composite cathode with the active material. The steps are as follows: S1, precursor mixing.

[0093] Weigh out phosphorus pentasulfide, elemental sulfur, and silicon disulfide according to their chemical formula molar ratios; the amount of sulfur source added is 110% of the theoretically measured molar amount.

[0094] S2 to S4, the complete set of process parameters are the same as in Example 6.

[0095] Example 12: This embodiment prepares an integrated composite cathode using Li6PS5Cl (a type of sulfide-germanium ore) as the solid electrolyte and NCM811 (a ternary material) as the active material. Except for the sulfur source ratio, all other process parameters are consistent with those in Example 1. The steps are as follows: S1. The electrolyte precursor is selected from phosphorus pentasulfide, elemental sulfur, and lithium chloride. The amount of elemental sulfur added is 100.1% of the theoretical molar amount. The material ratio and mixing method are the same as in the original Example 1.

[0096] The complete set of process parameters for S2 to S4, hot pressing, lithiation, and sintering are completely consistent with those of the original Example 1.

[0097] Example 13: This embodiment prepares an integrated composite cathode using Li6PS5Cl (a type of sulfide-germanium ore) as the solid electrolyte and NCM811 (a ternary material) as the active material. Except for the sulfur source ratio, all other process parameters are consistent with those in Example 1. The steps are as follows: S1. The amount of elemental sulfur added is 110% of the theoretical molar amount; the material ratio and mixing method are the same as in the original Example 1.

[0098] S2 to S4, the complete set of process parameters are completely consistent with those of the original Example 1.

[0099] Example 14: This embodiment prepares an integrated composite cathode using Li6PS5Cl (a type of silver sulfide germanium ore) as the solid electrolyte and NCM811 (a ternary material) as the active material. The steps are as follows: S1. The amount of elemental sulfur added is 120% of the theoretical molar amount; the material ratio and mixing method are the same as in the original Example 1.

[0100] S2 to S4, the complete set of process parameters are completely consistent with those of the original Example 1.

[0101] Example 15: The steps are as follows: S1. The sulfur source is only elemental sulfur, the phosphorus source is phosphorus pentasulfide, and the halogen source is a mixture of lithium chloride and lithium bromide. The ratio and mixing method of the precursor, NCM811, conductive agent, and PTFE binder are the same as in the original Example 1.

[0102] The process parameters for S2 to S4, hot pressing, lithiation, and sintering are the same as those in the original Example 1.

[0103] Example 16: A mixed sulfur source is used: a composite system of elemental sulfur and disulfur dichloride. The steps are as follows: S1. The sulfur source is a composite sulfur source of elemental sulfur and disulfur dichloride (molar ratio 9:1), and the total sulfur content meets the theoretical measurement requirements. The overall sulfur source is in excess to 110% of the theoretical value. The phosphorus source is phosphorus pentasulfide, and the halogen source is a mixture of lithium chloride and lithium bromide. The ratio and mixing method of the precursor, NCM811, conductive agent, and PTFE binder are the same as in the original Example 1.

[0104] S2 to S4, the complete set of process parameters are the same as those in the original Example 1.

[0105] Example 17: The solid electrolyte was Li6PS5Cl, and all preparation process parameters were fixed to the standard of Example 1, with only the positive electrode active material system adjusted. The steps are as follows: S1. The electrode material is lithium iron phosphate (LFP). The mass ratio of electrolyte precursor, conductive carbon black, PTFE binder and positive electrode material is 15:2:3:80. The sulfur source is in excess to 110% of the theoretical value. The mixing method is the same as in the original Example 1.

[0106] The parameters for S2 to S4, hot pressing, lithiation, and sintering are the same as those in the original Example 1.

[0107] Example 18: The steps are as follows: S1. The electrode material is a composite system, with NCM811, lithium cobalt oxide (LCO), and elemental sulfur in a mass ratio of 6:3:1; the proportions of other materials, the sulfur source ratio, and the mixing method are the same as in the original Example 1.

[0108] S2 to S4, the complete set of process parameters are the same as those in the original Example 1.

[0109] Examples 19-45: The solid electrolyte was Li6PS5Cl, and the electrode material was NCM811. In steps S1, S3, and S4, the parameters followed the standards of Example 1. In step S2, three horizontal gradients were selected: pressure (10MPa, 255MPa, 500MPa), temperature (15℃, 82℃, 150℃), and holding time (0.1min, 15min, 30min). Experiments were conducted using all three factors, resulting in 27 sets of examples, as shown in Table 1.

[0110] Table 1 Example 46: The solid electrolyte is Li6PS5Cl, and the electrode material is NCM811. In steps S1, S2, and S4, the parameters follow the standard of the original Example 1. In step S3, the prefabricated electrode is assembled into a coin cell, with an input current of 0.1 mA / cm². 2 Discharge to 2V at current density to complete the in-situ lithiation reaction.

[0111] Example 47: The solid electrolyte is Li6PS5Cl, and the electrode material is NCM811. In steps S1, S2, and S4, the parameters follow the standard of Example 1. In step S3, the prefabricated electrode is assembled into a coin cell, with an input current of 5 mA / cm². 2Discharge to 2V at current density to complete the in-situ lithiation reaction.

[0112] Example 48: The solid electrolyte is Li6PS5Cl, and the electrode material is NCM811. In steps S1, S2, and S4, the parameters follow the standard of Example 1. In step S3, the prefabricated electrode is assembled into a coin cell, with an input current of 10 mA / cm². 2 Discharge to 2 V at current density to complete the in-situ lithiation reaction.

[0113] Examples 49-57: The solid electrolyte is Li6PS5Cl, and the electrode material is NCM811. In steps S1, S2, and S3, the parameters follow the standard of Example 1. In step S4, the inert atmosphere is argon, and the cooling method is furnace cooling. Two levels and three gradients are selected: sintering temperature (200℃, 300℃, 400℃) and sintering time (2h, 6h, 10h). A total of 9 examples are presented, as shown in Table 2.

[0114] Table 2 Comparative Example 1: A composite cathode was prepared using a traditional process. The steps are as follows: First, Li6PS5Cl electrolyte powder of sulfogermanium ore type was pre-synthesized by mechanical ball milling.

[0115] Then, in a glove box, the pre-synthesized electrolyte powder is dry-mixed with NMC811 active material, conductive carbon black (SuperP), and PTFE binder at a mass ratio of 15:80:2:3.

[0116] Then, pure Li6PS5Cl electrolyte powder and a mixture containing NCM811 active material were cold-pressed on aluminum foil under a pressure of 300 MPa to form a conventional Li6PS5Cl solid electrolyte membrane and a composite positive electrode sheet, respectively. The surface loading of the active material was the same as in Example 1. Steps S3 and S4 were omitted.

[0117] Comparative Example 2: Composite cathodes were prepared using a traditional mechanical mixing method. The steps are as follows: First, Li was synthesized according to the method in Example 1. 10 GeP2S 12 Electrolyte powder.

[0118] Then, in the glove box, NCM811 active material and Li 10 GeP2S 12 Electrolyte powder, Super P conductive agent and PTFE binder are dry-mixed at a mass ratio of 80:15:3:2.

[0119] The mixture was then pressed onto aluminum foil using the same hot-pressing process as in Example 1 (150°C, 200 MPa, 2 min) to produce conventional Li. 10 GeP2S 12 Solid electrolyte membrane and composite cathode.

[0120] The performance of the electrolyte membranes obtained in Examples 1-57 and Comparative Examples 1 and 2 was tested.

[0121] (1) Electrolyte EIS test.

[0122] The electrolyte membranes obtained in each embodiment and comparative example were subjected to EIS testing. The method is as follows: Stainless steel current collectors were installed at both ends and sealed with sealant to ensure that the electrolyte does not come into contact with air. All the above operations were carried out in an argon atmosphere. The electrochemical impedance spectroscopy (EIS) of different composite electrolyte membranes was measured using an electrochemical workstation (Shanghai Chenhua). The conductivity can be calculated from the electrolyte impedance. The test results are shown in Table 3.

[0123] Table 3. Ionic conductivity data for each embodiment and comparative example. Based on the data in Table 3, it can be seen that: The electrolyte membranes provided in Examples 1-57 of this invention, due to the use of the method defined in the claims, allow for in-situ generation of the sulfide electrolyte inside the electrode, resulting in thorough mixing between different precursor components, a large interfacial contact area, and low impedance. Therefore, their impedance is significantly lower than that of Comparative Example 1 using a conventional pre-synthetic mixing process. This lower interfacial impedance is beneficial for lithium-ion conduction, leading to a higher ionic conductivity (2.8 × 10⁻⁶) in the electrolyte membranes of Examples 1-57. - ³S / cm~9.7×10 - The concentrations (³ S / cm) are all higher than those of the traditional premixing process comparison. This indicates that the integrated preparation method of the present invention can effectively optimize the internal structure of the electrode and improve electrochemical performance.

[0124] As shown in Table 3, and by comparing Examples 12 to 14, controlling the sulfur source to a slight excess within the range of 100.1% to 120% can effectively compensate for the loss of sulfur elements during electrochemical lithiation and high-temperature sintering, ensuring the integrity of the crystalline phase and the stability of the ionic conductivity of the sulfide solid electrolyte. Within this range, no free elemental sulfur impurities will be generated, which can avoid problems such as increased electrode internal resistance and decreased cycle performance.

[0125] (2) XRD phase characterization.

[0126] The sulfide electrolyte membranes prepared in Examples 1, 2, 12, 53, and Comparative Example 1 were characterized by XRD and obtained the following results: Figure 2 The XRD pattern mentioned above. From Figure 2 It can be seen that the XRD crystal phases of the sulfide electrolytes prepared by all compliant process embodiments of the present invention (sulfur source 100.1%~120%, sintering 200~400 ℃, hot pressing / lithiation within the claim range) all conform to the characteristic peaks of Li6PS5Cl, proving that the in-situ lithiation + sintering reaction is complete; the spectrum of Comparative Example 1 shows multiple impurity peaks of both electrolyte and raw material precursor, indicating that the premixed powder is only physically mixed without chemical bonding, the raw material residue is serious, and the crystal phase uniformity is extremely poor.

[0127] (3) The sulfide electrolyte membranes prepared in Example 1 and Comparative Example 1 were assembled into Li symmetric cells and then tested.

[0128] After attaching lithium foil to both ends, a Li-symmetric cell was formed. Then, an A / cm² pressure of 0.3 mA was applied across the Li-symmetric cell. 2 Charging with a constant current density for 10 minutes, discharging for 10 minutes, and cycling continuously for 500 hours yielded the following result: Figure 9 , Figure 10 The graph shows the results of the cyclic performance test. From... Figure 5 , Figure 6 It can be seen that the polarization of the Li symmetric cell in Example 1 is significantly reduced compared to the Li symmetric cell in Comparative Example 1, and the stability of lithium is significantly improved.

[0129] (4) Solid-state battery performance test.

[0130] Using the integrated composite cathode 1 prepared in Example 1 and the cathode pair prepared in Comparative Example 1 as working electrodes, lithium metal as the counter electrode, and cold-pressed Li6PS5Cl as the solid electrolyte layer, all-solid-state batteries were assembled. Their charge-discharge curves and cycle performance (0.5C charge-discharge, voltage range 2.5–4.2 V) were tested at 25°C. The test results are shown below. Figure 7 , 8 As shown.

[0131] Figure 7 , 8 The results showed that the initial discharge capacity of the all-solid-state battery composed of Example 1 was significantly higher than that of the all-solid-state battery composed of Comparative Example 1. This was due to the high ionic conductivity of the solid electrolyte in Example 1, which resulted in a sufficient initial discharge reaction. Figure 9 , Figure 10 The results show that, after cycling at a 0.5C rate, the all-solid-state battery composed of Example 1 retains 91% of its capacity after 400 cycles, while the solid-state battery composed of Comparative Example 1 retains 76% of its capacity after 340 cycles. This indicates that the solid-state electrolyte prepared by the method of the present invention has better high-voltage stability and can be matched with a high-voltage positive electrode to achieve good cycling performance.

[0132] In summary, the integrated composite electrode prepared by electrochemical in-situ lithiation results in a more uniform and dense sulfide solid electrolyte and positive electrode active material due to more thorough mixing of the precursor, leading to a 2-3 times higher ionic conductivity compared to the comparative example. Furthermore, the tightly packed structure formed by the sulfide solid electrolyte and active positive electrode material in the prepared integrated composite electrode improves interfacial contact and significantly enhances interfacial stability. This results in reduced polarization in the Li symmetric battery after 500 hours, a 2-fold increase in cycle life, and significantly improved lithium stability, leading to better battery cycle performance.

[0133] It should be noted that in this article, relational terms such as first and second are only used to refer to... Distinguishing one entity or operation from another does not necessarily require or imply any such actual relationship or order between those entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0134] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an integrated composite electrode, characterized in that, Includes the following steps: S1. Weigh an electrolyte precursor with a lithium content lower than the theoretical stoichiometric ratio of the target sulfide solid electrolyte according to the component ratio required for preparing the target sulfide solid electrolyte, and mix and grind the electrolyte precursor with electrode material, conductive agent and binder to obtain a mixture. S2. Load the mixture onto the surface and / or internal pores of the current collector, and then compact it to obtain a prefabricated electrode; S3. The pre-fabricated electrode is placed in an electrochemical reaction device containing a lithium source to carry out a lithiation reaction, so that a lithium sulfide precursor is generated in situ in the pre-fabricated electrode. S4. The pre-fabricated electrode after step S3 is placed in an inert atmosphere for sintering treatment, so that the electrolyte precursor in step S1 reacts with the lithium sulfide precursor generated in situ in step S3 to generate a sulfide solid electrolyte in situ. After cooling, the integrated composite electrode is obtained.

2. The method for preparing an integrated composite electrode according to claim 1, characterized in that, In step S1: When the crystal form of the target sulfide solid electrolyte is silver-germanium sulfide, the electrolyte precursor is prepared according to the corresponding Li 7-n PS 6- n X n The chemical formula uses the molar ratio of elements from phosphorus source, sulfur source, and halogen source, where X includes at least one of Cl, Br, and I, and 0 <n≤1.8; When the crystal form of the target sulfide solid electrolyte is LGPS, the electrolyte precursor is prepared according to the corresponding Li 11-n M 2-n P 1+ n S 12 The chemical formula uses phosphorus, sulfur, germanium, tin, and silicon as source materials, where M includes at least one of Ge, Sn, and Si, and 0. <n≤1.8。 3. The method for preparing an integrated composite electrode according to claim 1, characterized in that: In step S1, the electrolyte precursor contains a sulfur source, and the amount of sulfur source added is 100.1% to 120% of the theoretical stoichiometric molar amount of the target sulfide solid electrolyte.

4. The method for preparing an integrated composite electrode according to claim 2, characterized in that: In step S1, the electrolyte precursor contains elemental sulfur as the sulfur source, phosphorus pentasulfide as the phosphorus source, and halogen source selected from at least one of lithium chloride, lithium bromide, and lithium iodide.

5. The method for preparing an integrated composite electrode according to claim 1, characterized in that: In step S1, the electrode material is selected from one of the following: positive electrode material, negative electrode material, or integrated composite material that combines electrochemical activity and ion / electron conduction function.

6. The method for preparing an integrated composite electrode according to claim 5, characterized in that: The positive electrode material is at least one of ternary materials, lithium cobalt oxide, lithium iron phosphate, sulfur, and sulfurized polyacrylonitrile, and the negative electrode material is at least one of silicon-based materials, carbon-based materials, tin-based materials, and oxides.

7. The method for preparing an integrated composite electrode according to claim 1, characterized in that: In step S2, the compaction process adopts a hot pressing process with a pressure of 10MPa to 500MPa, a temperature of 15℃ to 150℃, and a holding time of 0.1min to 30min.

8. The method for preparing an integrated composite electrode according to claim 1, characterized in that: In step S2, the current collector is selected from at least one of metal foil, conductive thin film material, or porous metal material; The metal foil includes at least one of copper foil, aluminum foil, nickel foil, titanium foil, or stainless steel foil; the conductive film material includes at least one of carbon fiber paper, porous carbon cloth, or composite current collector; and the porous metal material includes at least one of foamed copper, foamed nickel, foamed aluminum, or metal fiber felt.

9. The method for preparing an integrated composite electrode according to claim 1, characterized in that: In step S3, the lithium source is either a lithium metal sheet or a pre-lithiation material; the electrochemical reaction is carried out at a current density of 0.1 to 10 mA / cm², and the lower limit cutoff voltage relative to the lithium metal reference electrode is 2.0 V.

10. A method for preparing an integrated composite electrode according to any one of claims 1-9, characterized in that: In step S4, the sintering temperature is 200℃~400℃, the sintering time is 2h~10h, and the cooling method is either furnace cooling or program-controlled cooling.

11. An integrated composite electrode, characterized in that: The composite electrode includes a current collector and an active composite layer loaded on the surface and / or internal pores of the current collector. The active composite layer contains an electrode material, a conductive agent, a binder, and a sulfide solid electrolyte. The sulfide solid electrolyte is prepared by reacting an electrolyte precursor with an in-situ generated lithium sulfide precursor, and the sulfide solid electrolyte and the electrode material form a three-dimensional network structure with a nanoscale interface fusion.

12. A battery, characterized in that: Includes the integrated composite electrode as described in claim 11.

13. A battery, characterized in that: Includes an integrated composite electrode prepared by any one of claims 1-10.

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