Sulfide solid-state battery and preparation method thereof

Abstract

The invention provides a sulfide solid-state battery and a preparation method thereof. The sulfide solid-state battery comprises a positive electrode material, a negative electrode material and a sulfide solid-state electrolyte membrane, the positive electrode material comprises a ternary positive electrode material matrix and a lithiation coating layer arranged on the surface of the ternary positive electrode material matrix, and the negative electrode material comprises a lithium metal body and a modified layer arranged on the surface of the lithium metal body. And the material of the modified layer comprises lithium-loving metal. Through synergistic modification of the positive electrode material and the negative electrode material, the first coulombic efficiency and the cycling stability of the sulfide solid-state battery are remarkably improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sulfide solid-state batteries, and particularly relates to a sulfide solid-state battery and a preparation method thereof. BACKGROUND

[0002] The all-solid-state lithium battery using non-combustible inorganic solid-state electrolyte instead of liquid organic electrolyte is considered as one of the ultimate solutions to solve the safety problems such as combustion and leakage of lithium batteries. At the same time, the application of lithium metal negative electrode can further improve the energy density of the battery. In recent years, thanks to the breakthrough in the lithium ion conductivity of inorganic solid-state electrolyte, sulfide solid-state electrolyte is considered as one of the most promising lithium ion conductors. However, there are still many challenges to be solved in the application process, including material instability, interface failure and lithium dendrite growth, etc.

[0003] In terms of negative electrode materials, in order to further improve the stability of lithium metal negative electrode, the prior art usually pre-constructs an artificial SEI layer on the surface of the lithium metal negative electrode, such as Li3N, LiF, Li2O, polymer or composite coating, etc. However, most of the artificial SEI layers are easy to break under the huge volume change of lithium deposition / peeling, and lithium dendrites will grow at the broken place. In addition, the modification methods disclosed in the prior art mostly block the expansion of lithium dendrites by establishing a barrier layer, and lack of active guidance to the deposition behavior of lithium ions, so the performance will still decrease after long-term use.

[0004] In terms of positive electrode materials, the prior art generally adopts the method of surface coating or setting buffer layer to modify the positive electrode material, so as to improve the interface contact performance. However, the formed coating layer or buffer layer has the problems of uneven thickness and poor consistency, and it is difficult to eliminate the interface side reaction.

[0005] Therefore, in the field, it is urgent to develop a sulfide solid-state battery and a preparation method thereof to solve the above problems. SUMMARY

[0006] In view of the deficiencies in the prior art, the purpose of the present application is to provide a sulfide solid-state battery and a preparation method thereof. The present application significantly improves the initial coulomb efficiency and cycle stability of the sulfide solid-state battery through the synergistic modification of the positive electrode material and the negative electrode material.

[0007] To achieve the purpose of the present application, the following technical solutions are adopted:

[0008] In a first aspect, the present application provides a sulfide solid-state battery, which comprises a positive electrode material, a negative electrode material and a sulfide solid-state electrolyte film, wherein the positive electrode material comprises a ternary positive electrode material matrix and a lithiation coating layer arranged on the surface of the ternary positive electrode material matrix, and the negative electrode material comprises a lithium metal body and a modified layer arranged on the surface of the lithium metal body, and the material of the modified layer comprises a lithiumophilic metal.

[0009] In one aspect, the present application performs surface modification treatment on a lithium metal negative electrode. The lithiumophilic metal contained in the modified layer can serve as an ideal lithium deposition nucleation site, significantly reduces the nucleation overpotential of lithium, induces uniform deposition of lithium ions, fundamentally eliminates the thermodynamic driving force for promoting lithium dendrite formation, effectively inhibits the growth of lithium dendrites, and reduces the interface impedance, thereby significantly improving the interface performance and cycle life of the sulfide solid-state battery. In another aspect, the present application can form a continuous, dense and uniform lithiation coating layer on the surface of the ternary positive electrode material, effectively avoiding direct contact between the ternary positive electrode material with high activity and the sulfide solid-state electrolyte film, inhibiting the positive electrode side interface side reaction and space charge layer effect, and being conducive to improving the cycle life of the sulfide solid-state battery.

[0010] In summary, the present application realizes the simultaneous improvement of the interface performance, cycle life and safety performance of the sulfide solid-state battery through the synergistic modification of the positive electrode material and the negative electrode material.

[0011] Preferably, the material of the lithiation coating layer comprises lithium borate.

[0012] Preferably, the thickness of the lithiation coating layer is 60-150 nm, for example, it can be 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm or 150 nm, etc. The values not listed in this range are also applicable. By adjusting the thickness of the lithiation coating layer to a reasonable range, the present application can effectively reduce the interface side reaction between the ternary positive electrode material and the sulfide solid-state electrolyte film, while ensuring the ion conduction efficiency.

[0013] Preferably, the general formula of the ternary positive electrode material matrix is LiNi x Co y Mn 1-x-y O2, 0.8≤x<1.0, 0<y<0.2, for example, x can be 0.8, y can be 0.1, x can be 0.85, y can be 0.05, x can be 0.88, y can be 0.02, or x can be 0.9, y can be 0.05, etc. The values not listed in this range are also applicable.

[0014] Preferably, the ternary positive electrode material matrix is LiNi 0.8Co 0.1 Mn 0.1 O2.

[0015] Preferably, the D of the ternary cathode material matrix 50 The particle size is 5μm-10μm, for example, it can be 5μm, 6μm, 7μm, 8μm, 9μm or 10μm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0016] Preferably, the lithiophilic metal comprises any one or a combination of at least two of tin, zinc, silver, or aluminum. These lithiophilic metals possess excellent lithiophilic properties and low nucleation overpotentials, effectively inducing preferential lithium deposition on their surface to form a dense and continuous lithium layer, significantly reducing the risk of lithium dendrite formation.

[0017] Preferably, the modified layer further comprises a lithium salt. The lithium salt effectively conducts lithium ions while providing electronic insulation, promoting uniform lithium ion deposition and accelerating the reaction kinetics on the negative electrode surface.

[0018] Preferably, the thickness of the modified layer is 1μm-5μm, for example, it can be 1μm, 2μm, 3μm, 4μm or 5μm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable. By controlling the thickness of the modified layer to a reasonable range, the present invention can effectively control the uniform nucleation and growth of metallic lithium, form a stable and uniform lithium deposition layer, and accelerate the transport of lithium ions.

[0019] Preferably, the material of the sulfide solid electrolyte membrane is selected from Li6PS5X, wherein X is selected from at least one of F, Cl, Br or I, and more preferably Li6PS5Cl, due to its high room temperature ionic conductivity (approximately 10). -3 It boasts a high S / cm ratio, relatively good air stability (compared to other sulfide solid electrolytes), and lower production costs.

[0020] Preferably, the thickness of the sulfide solid electrolyte membrane is 50μm-100μm, for example, it can be 50μm, 60μm, 70μm, 80μm, 90μm or 100μm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] In a second aspect, the present invention provides a method for preparing a sulfide solid-state battery as described in the first aspect, the method comprising the following steps:

[0022] A precursor material that is a mixture of ternary cathode material and lithiation coating is heat-treated to form a lithiation coating, thus obtaining the cathode material.

[0023] The salt solution containing the lithiophilic metal element is coated on the surface of the lithium metal to form a modified layer, thereby obtaining the negative electrode material.

[0024] The positive electrode material, the negative electrode material and the sulfide solid electrolyte membrane are assembled to obtain the sulfide solid battery.

[0025] Preferably, the precursor material of the lithiated coating layer comprises boric acid.

[0026] Preferably, the mass ratio of the ternary positive electrode material to the precursor material of the lithiated coating layer is 100:(3-4), for example, can be 100:3, 100:3.2, 100:3.5, 100:3.8 or 100:4, etc., not only limited to the listed values, other values not listed in this range are also applicable

[0027] Preferably, the temperature of the heat treatment is 300-400℃, and the time of the heat treatment is 15-18h.

[0028] Specifically, the temperature of the heat treatment can be, for example, 300℃, 320℃, 350℃, 380℃ or 400℃, etc.; the time of the first heating can be, for example, 15h, 16h, 17h or 18h, etc., not only limited to the listed values, other values not listed in this range are also applicable.

[0029] In the present application, the boric acid precursor material will melt at about 170℃, and the molten boric acid can uniformly wet the surface of the ternary positive electrode material particles, laying a foundation for forming a continuous, dense and uniform thin layer coating. Subsequently, when the temperature of the heat treatment continues to rise to above 300℃, the boric acid begins to dehydrate to generate boric anhydride and water vapor, and the highly active B2O3 will react with the lithium compounds on the surface of the ternary positive electrode material particles, finally forming a lithium borate coating. The prior art adopts solid oxide coating or film coating, which is difficult to achieve the above-mentioned effect, and the formed coating has the defects of uneven thickness, discontinuity and looseness.

[0030] In the present application, an exemplary preparation method of a positive electrode sheet comprising the above-mentioned positive electrode material is provided, which comprises the following steps: uniformly dry mixing the positive electrode material, the conductive agent and the binder in a high-speed mixer at a mass ratio of 70:20:(4-5) to obtain a mixed powder; and rolling the mixed powder to obtain a self-supporting positive electrode sheet.

[0031] Specifically, the mass ratio of the positive electrode material, the conductive agent and the binder may be, for example, 70:20:4, 70:20:4.2, 70:20:4.5, 70:20:4.8 or 70:20:5, and is not limited to the listed values, and other values not listed within the range of the values are also applicable.

[0032] Preferably, the pressure of the rolling is 40-60 MPa, and the speed of the rolling is 50-60 m / min.

[0033] Specifically, the pressure of the rolling may be, for example, 40 MPa, 45 MPa, 50 MPa, 55 MPa or 60 MPa, and the speed of the rolling may be, for example, 50 m / min, 52 m / min, 55 m / min, 58 m / min or 60 m / min, and is not limited to the listed values, and other values not listed within the range of the values are also applicable.

[0034] Preferably, the thickness of the positive electrode tab is 50-200 μm, for example, 50 μm, 80 μm, 100 μm, 150 μm or 200 μm, and is not limited to the listed values, and other values not listed within the range of the values are also applicable.

[0035] Preferably, the coating method comprises spraying.

[0036] Preferably, the salt solution containing the lithium-philic metal element comprises a lithium-philic metal salt.

[0037] Preferably, the lithium-philic metal salt comprises any one or a combination of at least two of tin chloride, zinc chloride, silver nitrate or aluminum chloride.

[0038] Preferably, the salt solution containing the lithium-philic metal element further comprises an organic solvent.

[0039] Preferably, the organic solvent comprises any one or a combination of at least two of diethyl carbonate, fluoroethylene carbonate, ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, dimethyl ether, N-methyl pyrrolidone, dimethyl formamide, carbon disulfide, toluene or xylene.

[0040] In the present application, when the salt solution containing the lithium-philic metal element is coated on the surface of the lithium metal, the lithium metal, due to its strong reducing property, can displace the lithium-philic metal ions in the salt solution containing the lithium-philic metal element by a displacement reaction to become lithium-philic metal element, and then the lithium-philic metal element can react with the remaining lithium metal to form an alloy layer, and the displaced lithium metal becomes lithium ions, which can combine with the anions in the original lithium-philic metal salt to form a lithium salt, thereby forming a modified layer.

[0041] Preferably, the preparation method of the sulfide solid electrolyte film comprises the following steps: mixing Li2S, P2S5 and LiCl in a molar ratio of (5-6):1:2 by a high-temperature solid phase method, ball milling in a planetary ball mill under inert gas protection at a rotating speed of 500r / min-600r / min for 10h-20h to form an amorphous precursor; heating and treating the amorphous precursor at 500℃-550℃ for 15h-18h in a vacuum sealed environment; after the end, placing it in a mold, and pressing by cold pressing technology, the cold pressing pressure is 300MPa-500MPa, and the pressure holding time is 30s-300s, to obtain the sulfide solid electrolyte film.

[0042] Specifically, the molar ratio of Li2S, P2S5 and LiCl may be, for example, 5:1:2, 5.2:1:2, 5.5:1:2, 5.8:1:2 or 6:1:2; the rotating speed may be, for example, 500r / min, 520r / min, 550r / min, 580r / min or 600r / min; the ball milling time may be, for example, 10h, 12h, 15h, 18h or 20h; the heating treatment temperature may be, for example, 500℃, 510℃, 530℃ or 550℃; the heating treatment time may be, for example, 15h, 16h, 17h or 18h; the cold pressing pressure may be, for example, 300MPa, 350MPa, 400MPa, 450MPa or 500MPa; and the pressure holding time may be, for example, 30s, 50s, 80s, 100s, 150s, 200s, 250s or 300s, and is not limited to the listed values, and other values not listed in the range are also applicable.

[0043] The numerical range of the present application includes not only the above-mentioned point values, but also any point values between the above-mentioned numerical ranges which are not mentioned, and the specific point values included in the range are not listed due to the length of the article and for the sake of simplicity.

[0044] Compared with the prior art, the present application has the following beneficial effects:

[0045] This invention provides a sulfide solid-state battery. On one hand, the invention modifies the surface of the lithium metal anode, where the lithiophilic metal in the modified layer serves as an ideal lithium deposition nucleation site, significantly reducing the lithium nucleation overpotential, inducing uniform lithium ion deposition, fundamentally eliminating the thermodynamic driving force promoting lithium dendrite formation, effectively suppressing lithium dendrite growth, reducing interfacial impedance, and thus significantly improving the interfacial performance and cycle life of the sulfide solid-state battery. On the other hand, this invention forms a continuous, dense, and uniform lithiation coating layer on the surface of the ternary cathode material, effectively avoiding direct contact between the highly active ternary cathode material and the sulfide solid electrolyte membrane, suppressing side reactions and space charge layer effects at the cathode side interface, which is beneficial for improving the cycle life of the sulfide solid-state battery.

[0046] In summary, this invention achieves simultaneous improvement in the interface performance, cycle life, and safety performance of sulfide solid-state batteries through the synergistic modification of the positive and negative electrode materials. Detailed Implementation

[0047] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0048] Example 1

[0049] This embodiment provides a sulfide solid-state battery, including a positive electrode material, a negative electrode material, and a Li6PS5Cl solid electrolyte membrane. The positive electrode material includes LiNi. 0.8 Co 0.1 Mn 0.1 O2 and set in LiNi 0.8 Co 0.1 Mn 0.1 The O2 surface has a lithium borate coating layer, and the negative electrode material includes a lithium metal body and a modification layer disposed on the surface of the lithium metal body. The modification layer is made of tin metal and lithium chloride.

[0050] Among them, LiNi 0.8 Co 0.1 Mn 0.1 O2's D 50 The particle size is 7 μm, the thickness of the lithium borate coating is 105 nm, the thickness of the modified layer is 3 μm, and the thickness of the Li6PS5Cl solid electrolyte membrane is 75 μm.

[0051] This embodiment also provides a method for preparing the above-mentioned sulfide solid-state battery, the method comprising the following steps:

[0052] LiNi 0.8 Co 0.1 Mn 0.1O2 and boric acid are mixed in a mass ratio of 100:3.5 and heat-treated at 350°C for 16 hours under a nitrogen atmosphere to form a lithium borate coating layer, thus obtaining the positive electrode material. The above positive electrode material, Li6PS5Cl solid electrolyte powder, Super P conductive agent, and polytetrafluoroethylene binder are dry-mixed evenly in a high-speed mixer in a mass ratio of 70:20:4.5:5.5 to obtain a mixed powder. The above mixed powder is then rolled to obtain a self-supporting positive electrode sheet with a thickness of 125μm, wherein the rolling pressure is 50MPa and the speed is 55m / min.

[0053] A tin chloride solution is sprayed onto the surface of lithium metal to form a modified layer, thus obtaining the negative electrode material.

[0054] A high-temperature solid-state method was used to mix Li₂S, P₂S₅, and LiCl in a molar ratio of 5.5:1:2. The mixture was then ball-milled in a planetary ball mill at 550 r / min for 15 h under nitrogen protection to form an amorphous precursor. The amorphous precursor was then heated at 520 °C for 16 h in a vacuum-sealed environment. After heating, the precursor was placed in a mold and pressed using a cold pressing technique at a pressure of 400 MPa for 62 s to obtain a sulfide solid electrolyte membrane.

[0055] First, the self-supporting positive electrode sheet is attached to one surface of the sulfide solid electrolyte membrane so that the surface of the self-supporting positive electrode sheet is in contact with the sulfide solid electrolyte membrane. Then, the negative electrode material is attached to the other surface of the sulfide solid electrolyte membrane so that the surface of the negative electrode material is in contact with the sulfide solid electrolyte membrane. The mixture is then pressed and formed at 150°C. The airtightness and internal resistance are checked, and a charge-discharge test is performed to complete the battery encapsulation and obtain the sulfide solid battery.

[0056] Example 2

[0057] This embodiment provides a sulfide solid-state battery, including a positive electrode material, a negative electrode material, and a Li6PS5Cl solid electrolyte membrane. The positive electrode material includes LiNi. 0.8 Co 0.1 Mn 0.1 O2 and set in LiNi 0.8 Co 0.1 Mn 0.1 The O2 surface has a lithium borate coating layer, and the negative electrode material includes a lithium metal body and a modification layer disposed on the surface of the lithium metal body. The modification layer is made of tin metal and lithium chloride.

[0058] Among them, LiNi 0.8 Co 0.1 Mn 0.1 O2's D 50The particle size is 5μm, the thickness of the lithium borate coating is 60nm, the thickness of the modified layer is 1μm, and the thickness of the Li6PS5Cl solid electrolyte membrane is 50μm.

[0059] This embodiment also provides a method for preparing the above-mentioned sulfide solid-state battery, the method comprising the following steps:

[0060] LiNi 0.8 Co 0.1 Mn 0.1 O2 and boric acid are mixed in a mass ratio of 100:3 and heat-treated at 300°C for 18 hours under a nitrogen atmosphere to form a lithium borate coating layer, thus obtaining the positive electrode material. The above positive electrode material, Li6PS5Cl solid electrolyte powder, Super P conductive agent and polytetrafluoroethylene binder are dry-mixed evenly in a high-speed mixer in a mass ratio of 70:20:4:6 to obtain a mixed powder. The above mixed powder is rolled to obtain a self-supporting positive electrode sheet with a thickness of 50μm, wherein the rolling pressure is 40MPa and the speed is 50m / min.

[0061] A tin chloride solution is sprayed onto the surface of lithium metal to form a modified layer, thus obtaining the negative electrode material.

[0062] A high-temperature solid-state method was used to mix Li₂S, P₂S₅, and LiCl in a molar ratio of 5:1:2. The mixture was then ball-milled in a planetary ball mill at 500 r / min for 20 h under nitrogen protection to form an amorphous precursor. The amorphous precursor was then heated at 500 °C for 18 h in a vacuum-sealed environment. After heating, the precursor was placed in a mold and pressed using a cold-pressing technique at a pressure of 300 MPa for 65 s to obtain a sulfide solid electrolyte membrane.

[0063] First, the self-supporting positive electrode sheet is attached to one surface of the sulfide solid electrolyte membrane so that the surface of the self-supporting positive electrode sheet is in contact with the sulfide solid electrolyte membrane. Then, the negative electrode material is attached to the other surface of the sulfide solid electrolyte membrane so that the surface of the negative electrode material is in contact with the sulfide solid electrolyte membrane. The mixture is then pressed and formed at 150°C. The airtightness and internal resistance are checked, and a charge-discharge test is performed to complete the battery encapsulation and obtain the sulfide solid battery.

[0064] Example 3

[0065] This embodiment provides a sulfide solid-state battery, including a positive electrode material, a negative electrode material, and a Li6PS5Cl solid electrolyte membrane. The positive electrode material includes LiNi. 0.8 Co 0.1 Mn 0.1 O2 and set in LiNi 0.8 Co0.1 Mn 0.1 The O2 surface has a lithium borate coating layer, and the negative electrode material includes a lithium metal body and a modification layer disposed on the surface of the lithium metal body. The modification layer is made of tin metal and lithium chloride.

[0066] Among them, LiNi 0.8 Co 0.1 Mn 0.1 O2's D 50 The particle size is 10 μm, the thickness of the lithium borate coating is 150 nm, the thickness of the modified layer is 5 μm, and the thickness of the Li6PS5Cl solid electrolyte membrane is 100 μm.

[0067] This embodiment also provides a method for preparing the above-mentioned sulfide solid-state battery, the method comprising the following steps:

[0068] LiNi 0.8 Co 0.1 Mn 0.1 O2 and boric acid are mixed in a mass ratio of 100:4 and heat-treated at 400°C for 15 hours under a nitrogen atmosphere to form a lithium borate coating layer, thus obtaining the positive electrode material. The above positive electrode material, Li6PS5Cl solid electrolyte powder, Super P conductive agent, and polytetrafluoroethylene binder are dry-mixed evenly in a high-speed mixer in a mass ratio of 70:20:5:5 to obtain a mixed powder. The above mixed powder is rolled to obtain a self-supporting positive electrode sheet with a thickness of 200μm, wherein the rolling pressure is 60MPa and the speed is 60m / min.

[0069] A tin chloride solution is sprayed onto the surface of lithium metal to form a modified layer, thus obtaining the negative electrode material.

[0070] A high-temperature solid-state method was used to mix Li₂S, P₂S₅, and LiCl in a molar ratio of 6:1:2. The mixture was then ball-milled in a planetary ball mill at 600 r / min for 10 h under nitrogen protection to form an amorphous precursor. The amorphous precursor was then heated at 550 °C for 15 h in a vacuum-sealed environment. After heating, the precursor was placed in a mold and pressed using a cold-pressing technique at a pressure of 500 MPa for 60 s to obtain a sulfide solid electrolyte membrane.

[0071] First, the self-supporting positive electrode sheet is attached to one surface of the sulfide solid electrolyte membrane so that the surface of the self-supporting positive electrode sheet is in contact with the sulfide solid electrolyte membrane. Then, the negative electrode material is attached to the other surface of the sulfide solid electrolyte membrane so that the surface of the negative electrode material is in contact with the sulfide solid electrolyte membrane. The mixture is then pressed and formed at 150°C. The airtightness and internal resistance are checked, and a charge-discharge test is performed to complete the battery encapsulation and obtain the sulfide solid battery.

[0072] Example 4

[0073] The difference between this embodiment and Embodiment 1 is that, in the preparation method, LiNi is used... 0.8 Co 0.1 Mn 0.1 O2 and boric acid were mixed in a mass ratio of 100:1, and everything else was the same as in Example 1.

[0074] Example 5

[0075] The difference between this embodiment and Embodiment 1 is that LiNi is used. 0.8 Co 0.1 Mn 0.1 O2 and boric acid were mixed in a mass ratio of 100:6, and everything else was the same as in Example 1.

[0076] Example 6

[0077] The difference between this embodiment and Embodiment 1 is that, in the preparation method, LiNi is used... 0.8 Co 0.1 Mn 0.1 O2 and boric acid were mixed in a mass ratio of 100:3.5 and heat-treated at 600°C for 8 hours under a nitrogen atmosphere to form a lithium borate coating layer, thus obtaining the positive electrode material. All other aspects were the same as in Example 1.

[0078] Comparative Example 1

[0079] The difference between this comparative example and Example 1 is that the cathode material is uncoated LiNi. 0.8 Co 0.1 Mn 0.1 The anode material is lithium metal that has not undergone modification treatment, and everything else is the same as in Example 1.

[0080] Comparative Example 2

[0081] The difference between this comparative example and Example 1 is that the cathode material is uncoated LiNi. 0.8 Co 0.1 Mn 0.1 O2, everything else is the same as in Example 1.

[0082] Comparative Example 3

[0083] The difference between this comparative example and Example 1 is that the negative electrode material is unmodified lithium metal, while everything else is the same as in Example 1.

[0084] Test conditions

[0085] The sulfide solid-state batteries provided in the above embodiments and comparative examples were subjected to electrochemical performance tests. The specific test method was as follows: the initial coulombic efficiency was tested at a rate of 0.1C at 25°C and a voltage range of 2.6V-4.2V; and the capacity retention rate was tested after 150 charge-discharge cycles at different rates of 0.33C and 0.5C.

[0086] The test results are shown in Table 1.

[0087] Table 1

[0088]

[0089] As can be seen from Table 1, compared with Comparative Example 1, Examples 1-3 of the present invention achieved simultaneous improvement in coulombic efficiency and cycle life of sulfide solid-state batteries through synergistic modification of positive and negative electrode materials.

[0090] Comparing Example 1 and Examples 4-5, it can be seen that LiNi 0.8 Co 0.1 Mn 0.1 The mass ratio of O2 to boric acid has a significant impact on the formation of the lithium borate coating. If it is not within the preferred range, it is difficult to form a continuous, dense, and uniform coating, which makes it difficult to effectively suppress interfacial side reactions and is detrimental to improving the cycle life of sulfide solid-state batteries.

[0091] Comparing Examples 1 and 6, it is evident that the heat treatment conditions have a significant impact on the quality of the formed lithium borate coating. If the conditions are not within the preferred range, the desired effect of improving the electrochemical performance of the sulfide solid-state battery cannot be achieved.

[0092] Comparing Example 1 and Comparative Examples 2-3, it can be seen that a single modification treatment cannot achieve all the technical effects of the present invention; both are indispensable.

[0093] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A sulfide solid-state battery, the sulfide solid-state battery comprising a positive electrode material, a negative electrode material, and a sulfide solid electrolyte membrane, characterized in that, The positive electrode material includes a ternary positive electrode material matrix and a lithiation coating layer disposed on the surface of the ternary positive electrode material matrix, and the negative electrode material includes a lithium metal body and a modification layer disposed on the surface of the lithium metal body, wherein the material of the modification layer includes a lithium-philic metal.

2. The sulfide solid-state battery according to claim 1, characterized in that, The material of the lithium-ion coating layer includes lithium borate; Preferably, the thickness of the lithiation coating layer is 60nm-150nm.

3. The sulfide solid-state battery according to claim 1 or 2, characterized in that, The general formula of the ternary cathode material matrix is ​​LiNi. x Co y Mn 1-x-y O2, 0.8≤x<1.0, 0<y<0.2; Preferably, the ternary cathode material matrix is ​​LiNi. 0.8 Co 0.1 Mn 0.1 O2; Preferably, the D of the ternary cathode material matrix 50 The particle size is 5μm-10μm.

4. The sulfide solid-state battery according to any one of claims 1-3, characterized in that, The lithiophilic metal includes any one or a combination of at least two of tin, zinc, silver, or aluminum; Preferably, the material of the modified layer further includes lithium salt; Preferably, the thickness of the modified layer is 1μm-5μm.

5. The sulfide solid-state battery according to any one of claims 1-4, characterized in that, The material of the sulfide solid electrolyte membrane is selected from Li6PS5X, wherein X is selected from at least one of F, Cl, Br or I; Preferably, the thickness of the sulfide solid electrolyte membrane is 50 μm-100 μm.

6. A method for preparing a sulfide solid-state battery as described in any one of claims 1-5, characterized in that, The preparation method includes the following steps: A precursor material that is a mixture of ternary cathode material and lithiation coating is heat-treated to form a lithiation coating, thus obtaining the cathode material. A salt solution containing a lithium-loving metal element is coated onto the surface of lithium metal to form a modified layer, thus obtaining the negative electrode material. The positive electrode material, the negative electrode material, and the sulfide solid electrolyte membrane are assembled to obtain the sulfide solid battery.

7. The preparation method according to claim 6, characterized in that, The precursor material for the lithium coating layer includes boric acid; Preferably, the mass ratio of the ternary cathode material to the precursor material of the lithiation coating layer is 100:(3-4); Preferably, the heat treatment temperature is 300℃-400℃, and the heat treatment time is 15h-18h.

8. The preparation method according to claim 6 or 7, characterized in that, The coating method includes spraying.

9. The preparation method according to any one of claims 6-8, characterized in that, The salt solution containing a lithium-loving metal element includes a lithium-loving metal salt; Preferably, the lithium-loving metal salt includes any one or a combination of at least two of tin chloride, zinc chloride, silver nitrate, or aluminum chloride.

10. The preparation method according to any one of claims 6-9, characterized in that, The salt solution containing a lithium-loving metal element also includes an organic solvent; Preferably, the organic solvent includes any one or a combination of at least two of the following: diethyl carbonate, fluoroethylene carbonate, ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, dimethyl ether, N-methylpyrrolidone, dimethylformamide, carbon disulfide, toluene, or xylene.

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