Solid state battery

Abstract

The invention provides a solid-state battery which comprises a positive electrode, a negative electrode and a solid-state electrolyte layer. The solid-state electrolyte layer is arranged between the positive electrode and the negative electrode, the solid-state electrolyte layer comprises sulfide solid-state electrolyte, and the sulfide solid-state electrolyte is represented by chemical formula 1: Li < 6 + x + y > P < 1-x-y > Si < x > Ti < y > S < 5-2x-2y > Br < 2 > x + 2y, in chemical formula 1, 0 < = x < = 0.5, 0 < = y < = 0.5, and x + y > 0.

Description

Technical Field

[0001] The present invention relates to a battery, and in particular to a solid-state battery. Background Art

[0002] With the development of the industry, liquid lithium batteries are widely used in electronic products, such as laptops, mobile phones, wearable devices, and even in the electric vehicle industry. However, when liquid lithium batteries are impacted by external forces, the flammable electrolyte in them may leak, volatilize, and cause dangers such as combustion and explosion. Therefore, in order to improve the safety of batteries, research on solid-state lithium batteries has recently begun, using solid electrolytes to replace the electrolytes in liquid lithium batteries to avoid the dangers that may be caused by leakage and volatilization of the above-mentioned electrolytes.

[0003] Among solid electrolytes, sulfide solid electrolytes have higher ionic conductivity. However, sulfide solid electrolytes have poor stability and are easily decomposed in air or high voltage environments, which affects their performance. Therefore, how to improve the stability of sulfide solid electrolytes is a problem that needs to be solved at present. Summary of the invention

[0004] The present invention is directed to a solid-state battery having good chemical and voltage stability and improved cycle life.

[0005] According to an embodiment of the present invention, a solid-state battery includes a positive electrode, a negative electrode, and a solid electrolyte layer. The solid electrolyte layer is disposed between the positive electrode and the negative electrode, wherein the solid electrolyte layer includes a sulfide solid electrolyte, and the sulfide solid electrolyte is represented by chemical formula 1:

[0006] [Chemical formula 1]

[0007] Li 6+x+y P 1-x-y Si x Ti y S 5-2x-2y B O 2x+2y ,

[0008] In Chemical Formula 1, 0≤x≤0.5, 0≤y≤0.5, and x+y>0.

[0009] In the solid-state battery according to an embodiment of the present invention, the above-mentioned sulfide solid electrolyte is represented by Chemical Formula 2:

[0010] [Chemical formula 2]

[0011] Li 6+x P 1-x Si x S 5-2x B O 2x ,

[0012] In Chemical Formula 2, 0.01≤x≤0.5.

[0013] In the solid-state battery according to an embodiment of the present invention, the above-mentioned sulfide solid electrolyte is represented by Chemical Formula 3:

[0014] [Chemical formula 3]

[0015] Li 6+y P 1-y Ti y S 5-2y B O 2y ,

[0016] In Chemical Formula 3, 0.01≤y≤0.5.

[0017] In the solid-state battery according to an embodiment of the present invention, the solid electrolyte layer has a double-layer structure, and the double-layer structure includes a first layer and a second layer stacked on each other. The first layer is arranged between the negative electrode and the second layer, and the second layer is arranged between the positive electrode and the first layer.

[0018] In the solid-state battery according to the embodiment of the present invention, the first layer of the solid-state electrolyte layer includes a sulfide solid-state electrolyte, and the second layer of the solid-state electrolyte layer includes a halide solid-state electrolyte.

[0019] In the solid-state battery according to the embodiment of the present invention, the above-mentioned halide solid electrolyte is selected from Li 3 InCl 6 , Li 3 AlF 6 , Li 3 G JZ 6 , Li 3 YC 6 Li 3 Yb 6 The group formed.

[0020] In the solid-state battery according to the embodiment of the present invention, the positive electrode includes a positive electrode active material, a solid electrolyte and a conductive additive.

[0021] In the solid-state battery according to an embodiment of the present invention, the positive electrode active material includes LiNi 0.9 Co 0.05 Mn 0.5 O 2 、LiNi 0.8 Co 0.1 Mn 0.1 O 2 、LiNi 0.6 Co 0.2 Mn 0.2 O 2、LiNi 0.6 Co 0.1 Mn 0.3 O 2 、LiNi 0.5 Co 0.2 Mn 0.3 O 2 、LiFePO 4 、Li(Fe x Mn 1-x )PO 4 or a combination thereof.

[0022] In the solid-state battery according to the embodiment of the present invention, the solid-state electrolyte in the positive electrode includes a halide solid-state electrolyte.

[0023] In the solid-state battery according to an embodiment of the present invention, the negative electrode includes lithium, indium, a lithium-indium alloy or a combination thereof.

[0024] Based on the above, the solid-state battery of the present invention comprises a solid-state battery having a chemical formula 1 (Li 6+x+y P 1-x-y Si x Ti y S 5-2x-2y B O 2x+2y , where 0≤x≤0.5, 0≤y≤0.5 and x+y>0), the sulfide solid electrolyte can therefore have good ionic conductivity, while improving the chemical stability and voltage stability of the sulfide solid electrolyte, thereby improving the cycle life of the solid-state battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of a solid-state battery according to an embodiment of the present invention.

[0026] Figure 2 These are the results of testing the amount of hydrogen sulfide generated by the solid electrolytes of Synthesis Examples 2 and 5 and Comparative Synthesis Example.

[0027] Figure 3 These are the results of linear sweep voltammetry measurements of the solid electrolytes of Synthesis Example 2 and Comparative Synthesis Example.

[0028] Figure 4 These are the results of linear sweep voltammetry measurements of the solid electrolytes of Synthesis Example 5 and Comparative Synthesis Example.

[0029] Figure 5 These are the results of a limiting current density test on a symmetrical battery obtained from a comparative synthesis example.

[0030] Figure 6 This is the result of the limiting current density test on the symmetrical battery obtained in Synthesis Example 2.

[0031] Figure 7 This is the result of the limiting current density test on the symmetrical battery obtained in Synthesis Example 5.

[0032] Figure 8 It is a charge and discharge curve of a comparative example.

[0033] Fig. 9 This is the charge and discharge curve of Example 1.

[0034] Fig.10 This is the charge and discharge curve of Example 2.

[0035] Fig.11 The figure shows the relationship between the number of charge and discharge cycles, the discharge capacitance and the coulomb efficiency of the comparative example, the first embodiment and the second embodiment. DETAILED DESCRIPTION

[0036] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and the description to refer to the same or like parts.

[0037] In the accompanying drawings, for the sake of clarity, the thickness of layers, films, panels, regions, etc. is magnified. Throughout the specification, the same reference numerals represent the same components. It should be understood that when a component such as a layer, film, region, or substrate is referred to as being "on" or "connected to" another component, it can be directly on or connected to another component, or an intermediate component can also exist. On the contrary, when a component is referred to as being "directly on" or "directly connected to" another component, there is no intermediate component. As used herein, "connection" can refer to physical and / or electrical connection. Furthermore, "electrical connection" or "coupling" can be the presence of other components between two components.

[0038] It should be understood that although the terms "first", "second", etc. may be used herein to describe various components, parts, regions, layers and / or parts, these components, parts, regions, and / or parts should not be limited by these terms. These terms are only used to distinguish one component, part, region, layer or part from another component, part, region, layer or part. Therefore, the "first component", "component", "region", "layer" or "part" discussed below may be referred to as a second component, part, region, layer or part without departing from the teachings of this article.

[0039] Figure 1 is a schematic diagram of a solid-state battery according to an embodiment of the present invention.

[0040] Please refer to Figure 1, the solid-state battery 100 includes a positive electrode 110, a negative electrode 120, and a solid electrolyte layer 130. The solid electrolyte layer 130 is disposed between the positive electrode 110 and the negative electrode 120, and the solid electrolyte layer 130 includes a sulfide solid electrolyte represented by Chemical Formula 1:

[0041] [Chemical Formula 1]

[0042] Li 6+x+y P 1-x-y Si x Ti y S 5-2x-2y BrO 2x+2y ,

[0043] In Chemical Formula 1, 0 ≤ x ≤ 0.5, 0 ≤ y ≤ 0.5 and x + y > 0.

[0044] In some embodiments, in Chemical Formula 1, 0 < x + y ≤ 0.5. In this way, the stability of the sulfide solid electrolyte can be improved, the possibility of decomposition of the sulfide solid electrolyte in air or under high voltage can be reduced, and thus the cycle life of the solid-state battery 100 can be improved.

[0045] In some embodiments, the sulfide solid electrolyte can be represented by Chemical Formula 2:

[0046] [Chemical Formula 2]

[0047] Li 6+x P 1-x Si x S 5-2x BrO 2x ,

[0048] wherein in Chemical Formula 2, 0.01 ≤ x ≤ 0.5.

[0049] In some embodiments, the sulfide solid electrolyte can be represented by Chemical Formula 3:

[0050] [Chemical Formula 3]

[0051] Li 6+y P 1-y Ti y S 5-2y BrO 2y ,

[0052] wherein in Chemical Formula 3, 0.01 ≤ y ≤ 0.5.

[0053] In some embodiments, the sulfide solid electrolyte is obtained by doping lithium 6 PS 5 Br into silica (SiO 2 ) and / or titanium dioxide (TiO 2) is formed. 6 PS 5 Br passes through silicon dioxide (SiO 2 ) and / or titanium dioxide (TiO 2 ) doping modification can increase the structural stability of the sulfide solid electrolyte, reduce the possibility of the sulfide solid electrolyte decomposing by reacting with water in the atmosphere or decomposing under high voltage, thereby improving its stability and thereby increasing the cycle life of the solid-state battery 100.

[0054] In some embodiments, the solid electrolyte layer 130 may be a double-layer structure. For example, the solid electrolyte layer 130 includes a first layer 132 and a second layer 134. The first layer 132 may include a sulfide solid electrolyte as represented by chemical formula 1, 2, or 3. The second layer 134 may include a halide solid electrolyte, which may be selected from Li 3 InCl 6 , Li 3 AlF 6 , Li 3 G JZ 6 , Li 3 YC 6 Li 3 Yb 6 In other embodiments, the solid electrolyte layer 130 may be a single-layer structure including the sulfide solid electrolyte represented by Chemical Formula 1, 2 or 3 as described above.

[0055] In some embodiments, the first layer 132 may be disposed between the negative electrode 120 and the second layer 134, and the second layer 134 may be disposed between the positive electrode 110 and the first layer 132. In this way, the material of the positive electrode 110 may be prevented from reacting with the sulfide solid electrolyte of the first layer 132.

[0056] In some embodiments, the positive electrode 110 includes a positive electrode active material, a solid electrolyte, and a conductive additive. The positive electrode active material may include, for example, LiNi 0.8 Co 0.1 Mn 0.1 O 2 、LiNi 0.6 Co 0.2 Mn 0.2 O 2 、LiNi 0.6 Co 0.1 Mn 0.3 O 2 、LiNi 0.5 Co 0.2 Mn 0.3 O 2Or a combination thereof. In some embodiments, the positive electrode active material may be a single crystal material or a polycrystalline material, but the present invention is not limited thereto. The conductive additive may include, for example, carbon black, vapor grown carbon fiber (VGCF), carbon nanotubes, graphene, a combination thereof, or other suitable conductive additives. The solid electrolyte in the positive electrode 110 may include, for example, a halide solid electrolyte, wherein specific examples of the halide solid electrolyte may be referred to above and will not be repeated here.

[0057] In some embodiments, the positive electrode 110 further includes an adhesive to bond the positive electrode active material, the solid electrolyte, and the conductive additive together. The adhesive may include, for example, polytetrafluoroethylene (PTFE), polyvinylidene difluoride (PVDF), or other suitable adhesives, but the present invention is not limited thereto.

[0058] In some embodiments, the negative electrode 120 may include lithium, indium, lithium-indium alloy, a combination thereof, or other suitable negative electrode materials. In some embodiments, the negative electrode 120 may also include a solid electrolyte, which may include, for example, a group consisting of a halide solid electrolyte and a sulfide solid electrolyte (specific examples of halide solid electrolytes and sulfide solid electrolytes may be referred to above and will not be repeated here), but the present invention is not limited thereto.

[0059] Since the solid-state battery in this embodiment includes the sulfide solid electrolyte represented by Chemical Formula 1, the chemical stability and voltage stability of the sulfide solid electrolyte can be improved while maintaining good ion conductivity, thereby improving the cycle life of the solid-state battery.

[0060] The following experiments are listed to verify the efficacy of the present invention, but the present invention is not limited to the following contents. The materials used, their amounts and ratios, processing details and processing procedures, etc. can be appropriately changed without exceeding the scope of the present invention. Therefore, the present invention should not be interpreted restrictively by the embodiments described below.

[0061] [Synthesis of sulfide solid electrolyte]

[0062] Synthesis Example 1: Li 6.1 P 0.9 Ti 0.1 S 4.8 B O 0.2

[0063] First, take 1.1266 g of Li 2 S, 0.8350 g of LiBr, 0.0768 g of TiO 2 and 0.9617 g of P2 S 5 Put it into a mortar and grind it roughly for 10 minutes to mix the powder evenly. Then put the mixed powder and zirconium oxide beads (diameter = 10mm) into a zirconium oxide ball mill at a weight ratio of (powder: zirconium oxide beads) of 1:10. Then put the ball mill into a ball mill and mill it at a speed of 500rpm for 20 hours. The ball mill will be taken out every 5 hours to remove the powder on the wall of the jar to prevent the powder from accumulating on the wall of the jar and causing uneven synthesis. After that, put the milled powder into a quartz tube with a carbon layer on the inner wall. Use a maintainer and a vacuum system to reduce the pressure in the quartz tube to 2*10 -2 Torr, and then the tube was sealed. Finally, the quartz tube containing the sample was sintered at a sintering temperature of 500°C and kept at the temperature for 5 hours before naturally cooling to room temperature to obtain Li 6.1 P 0.9 Ti 0.1 S 4.8 B O 0.2 .

[0064] Synthesis Example 2: Li 6.2 P 0.8 Ti 0.2 S 4.6 B O 0.4

[0065] First, take 1.1517 g of Li 2 S, 0.8372 g of LiBr, 0.1540 g of TiO 2 and 0.8571 g of P 2 S 5 Put it into a mortar and grind it roughly for 10 minutes to mix the powder evenly. Then put the mixed powder and zirconium oxide beads (diameter = 10mm) into a zirconium oxide ball mill at a weight ratio of (powder: zirconium oxide beads) of 1:10. Then put the ball mill into a ball mill and mill it at a speed of 500rpm for 20 hours. The ball mill will be taken out every 5 hours to remove the powder on the wall of the jar to prevent the powder from accumulating on the wall of the jar and causing uneven synthesis. After that, put the milled powder into a quartz tube with a carbon layer on the inner wall. Use a maintainer and a vacuum system to reduce the pressure in the quartz tube to 2*10 -2 Torr, and then the tube was sealed. Finally, the quartz tube containing the sample was sintered at a sintering temperature of 500°C and kept at the temperature for 5 hours before naturally cooling to room temperature to obtain Li 6.2 P 0.8 Ti 0.2 S 4.6 B O 0.4 .

[0066] Synthesis Example 3: Li 6.3 P 0.7 Ti0.3 S 4.4 B O 0.6

[0067] First, take 0.9388 g of Li 2 S, 0.8403 g of LiBr, 0.2225 g of TiO 2 and 1.0314 g of P 2 S 5 Put it into a mortar and grind it roughly for 10 minutes to mix the powder evenly. Then put the mixed powder and zirconium oxide beads (diameter = 10mm) into a zirconium oxide ball mill at a weight ratio of (powder: zirconium oxide beads) of 1:10. Then put the ball mill into a ball mill and mill it at a speed of 500rpm for 20 hours. The ball mill will be taken out every 5 hours to remove the powder on the wall of the jar to prevent the powder from accumulating on the wall of the jar and causing uneven synthesis. After that, put the milled powder into a quartz tube with a carbon layer on the inner wall. Use a maintainer and a vacuum system to reduce the pressure in the quartz tube to 2*10 -2 Torr, and then the tube was sealed. Finally, the quartz tube containing the sample was sintered at a sintering temperature of 500°C and kept at the temperature for 5 hours before naturally cooling to room temperature to obtain Li 6.3 P 0.7 Ti 0.3 S 4.4 B O 0.6 .

[0068] Synthesis Example 4: Li 6.1 P 0.9 Si 0.1 S 4.8 B O 0.2

[0069] First, take 1.1337 g of Li 2 S, 0.8403 g of LiBr, 0.0581 g of SiO 2 and 0.9678 g of P 2 S 5 Put it into a mortar and grind it roughly for 10 minutes to mix the powder evenly. Then put the mixed powder and zirconium oxide beads (diameter = 10mm) into a zirconium oxide ball mill at a weight ratio of (powder: zirconium oxide beads) of 1:10. Then put the ball mill into a ball mill and mill it at a speed of 500rpm for 20 hours. The ball mill will be taken out every 5 hours to remove the powder on the wall of the jar to prevent the powder from accumulating on the wall of the jar and causing uneven synthesis. After that, put the milled powder into a quartz tube with a carbon layer on the inner wall. Use a maintainer and a vacuum system to reduce the pressure in the quartz tube to 2*10 -2Torr, and then the tube was sealed. Finally, the quartz tube containing the sample was sintered at a sintering temperature of 500°C and kept at the temperature for 5 hours before naturally cooling to room temperature to obtain Li 6.1 P 0.9 Si 0.1 S 4.8 B O 0.2 .

[0070] Synthesis Example 5: Li 6.3 P 0.7 Si 0.3 S 4.4 B O 0.6

[0071] First, take 1.200 g of Li 2 S, 0.8558 g of LiBr, 0.1776 g of SiO 2 and 0.7666 g of P 2 S 5 Put it into a mortar and grind it roughly for 10 minutes to mix the powder evenly. Then put the mixed powder and zirconium oxide beads (diameter = 10mm) into a zirconium oxide ball mill at a weight ratio of (powder: zirconium oxide beads) of 1:10. Then put the ball mill into a ball mill and mill it at a speed of 500rpm for 20 hours. The ball mill will be taken out every 5 hours to remove the powder on the wall of the jar to prevent the powder from accumulating on the wall of the jar and causing uneven synthesis. After that, put the milled powder into a quartz tube with a carbon layer on the inner wall. Use a maintainer and a vacuum system to reduce the pressure in the quartz tube to 2*10 -2 Torr, and then the tube was sealed. Finally, the quartz tube containing the sample was sintered at a sintering temperature of 500°C and kept at the temperature for 5 hours before naturally cooling to room temperature to obtain Li 6.3 P 0.7 Si 0.3 S 4.4 B O 0.6 .

[0072] Synthesis Example 6: Li 6.5 P 0.5 Si 0.5 S 4.0 B O 1.0

[0073] First, take 1.2686 g of Li 2 S, 0.8719 g of LiBr, 0.3016 g of SiO 2 and 0.5579 g of P 2 S 5Put it into a mortar and grind it roughly for 10 minutes to mix the powder evenly. Then put the mixed powder and zirconium oxide beads (diameter = 10mm) into a zirconium oxide ball mill at a weight ratio of (powder: zirconium oxide beads) of 1:10. Then put the ball mill into a ball mill and mill it at a speed of 500rpm for 20 hours. The ball mill will be taken out every 5 hours to remove the powder on the wall of the jar to prevent the powder from accumulating on the wall of the jar and causing uneven synthesis. After that, put the milled powder into a quartz tube with a carbon layer on the inner wall. Use a maintainer and a vacuum system to reduce the pressure in the quartz tube to 2*10 -2 Torr, and then the tube was sealed. Finally, the quartz tube containing the sample was sintered at a sintering temperature of 500°C and kept at the temperature for 5 hours before naturally cooling to room temperature to obtain Li 6.5 P 0.5 Si 0.5 S 4.0 B O 1.0 .

[0074] Comparative Synthesis Example: Li 6 PS 5 Br

[0075] First, take 1.1015 g of Li 2 S, 0.8328 g of LiBr and 1.0657 g of P 2 S 5 Put it into a mortar and grind it roughly for 10 minutes to mix the powder evenly. Then put the mixed powder and zirconium oxide beads (diameter = 10mm) into a zirconium oxide ball mill at a weight ratio of 1:10 (powder: zirconium oxide beads). Then put the ball mill into a ball mill and mill it at a speed of 500rpm for 20 hours. The ball mill will be taken out every 5 hours to remove the powder on the wall of the jar to prevent the powder from accumulating on the wall of the jar and causing uneven synthesis. After that, the milled powder is placed in a quartz tube with a carbon layer on the inner wall. The pressure in the quartz tube is reduced to 2*10 by using a maintainer and a vacuum system. -2 Torr and then sealed the tube. Finally, the quartz tube containing the sample was sintered at a sintering temperature of 500 ° C and kept at the temperature for 5 hours and then naturally cooled to room temperature to obtain Li 6 PS 5 Br.

[0076] The ionic conductivity of the above-mentioned Synthesis Examples 1 to 6 and the Comparative Synthesis Examples was measured at room temperature using a solid electrolyte pressure mold KP cell, and the results are recorded in Table 1. In addition, for Synthesis Examples 2, 5 and the Comparative Synthesis Examples, they were exposed to air for 30 minutes, and the hydrogen sulfide (H 2 The results are shown in Table 1 and Figure 2 middle. Figure 2These are the results of testing the amount of hydrogen sulfide generated by the solid electrolytes of Synthesis Examples 2 and 5 and Comparative Synthesis Example.

[0077] Table 1

[0078]

[0079] From Table 1 and Figure 2 It can be seen that compared with the undoped sulfide solid electrolyte (i.e., comparative synthesis example), the TiO 2 or SiO 2 The doped sulfide solid electrolyte (ie, Synthesis Examples 1 to 6) has good ionic conductivity at room temperature and can reduce the generation of hydrogen sulfide, thereby improving the chemical stability of the sulfide solid electrolyte.

[0080] In addition, the solid electrolytes of Synthesis Examples 2, 5 and Comparative Synthesis Example were respectively sandwiched between two lithium electrodes to form a symmetrical battery, and then linear sweep voltammetry measurement, limiting current density test and long cycle test were performed.

[0081] The linear sweep voltammetry measurement was performed by measuring the current change of the symmetrical cells obtained from Synthesis Examples 2 and 5 and Comparative Synthesis Example in the voltage range of 0 V to 7 V at a scan rate of 0.1 mV / s. Figure 3 These are the results of linear sweep voltammetry measurements of the solid electrolytes of Synthesis Example 2 and Comparative Synthesis Example. Figure 4 These are the results of linear sweep voltammetry measurements of the solid electrolytes of Synthesis Example 5 and Comparative Synthesis Example.

[0082] Depend on Figure 3 and Figure 4 It can be seen that compared with the situation in which the current of the comparative synthesis example fluctuates up and down when the voltage is increased, the synthesis examples 2 and 5 have stable current performance when the voltage is increased. 2 or SiO 2 Doped sulfide solid electrolytes have good stability under high pressure.

[0083] The limiting current density test was conducted by subjecting the symmetrical cells obtained from Synthesis Examples 2, 5 and Comparative Synthesis Examples to a current density of 0.05 mA / cm 2 The current density was increased by 0.05 mA / cm per turn. 2 The current density is 2 minutes per charge and discharge cycle, and the potential change is measured. When the potential drops sharply, it indicates that the battery has failed. Figure 5 These are the results of a limiting current density test on a symmetrical battery obtained from a comparative synthesis example. Figure 6This is the result of the limiting current density test on the symmetrical battery obtained in Synthesis Example 2. Figure 7 This is the result of the limiting current density test on the symmetrical battery obtained from Synthesis Example 5. Figures 5 to 7 In the figure, the ordinate on the left is the value corresponding to the solid line, and the ordinate on the right is the value corresponding to the dotted line.

[0084] Depend on Figures 5 to 7 It can be seen that the limiting current density of the symmetrical battery obtained from the comparative synthesis example is about 0.5 mA / cm 2 The limiting current density of the symmetrical battery obtained from Synthesis Example 2 is about 2.0 mA / cm 2 The limiting current density of the symmetrical battery obtained from Synthesis Example 5 is about 1.25 mA / cm 2 . It can be seen that after TiO 2 or SiO 2 Doped sulfide solid electrolytes help to improve the limiting current density of solid-state batteries.

[0085] The long cycle test was conducted by subjecting the symmetrical cells obtained from Synthesis Examples 2, 5 and Comparative Synthesis Example to a current of 0.1 mA / cm 2 The lithium-lithium charging test is carried out at a current density of 1 hour per cycle, and the potential change is measured. When the potential drops sharply, it indicates that the battery has failed.

[0086] The results of the long cycle test show that the symmetrical battery obtained from the comparative synthesis example can be continuously cycled for 18 cycles in the long cycle test, the symmetrical battery obtained from synthesis example 2 can be continuously cycled for 30 cycles in the long cycle test, and the symmetrical battery obtained from synthesis example 5 can be continuously cycled for 520 cycles in the long cycle test. 2 or SiO 2 Doped sulfide solid electrolytes help improve the cycle life of solid-state batteries.

[0087] [Preparation of solid-state batteries]

[0088] Example 1

[0089] Preparation of positive electrode: Single crystal-LiNi 0.6 Co 0.1 Mn 0.3 O 2 (SC-NCM613) (positive electrode active material), Li 3 InCl 6 (solid electrolyte) and VGCF (conductive additive) were put into a mortar at a weight ratio of 70:30:3 and mixed evenly, and then 3 wt% PTFE (adhesive) was added to form a film. The film was rolled to a thickness of 50 μm and cut into a circle with a diameter of 10 mm.

[0090] Preparation of solid electrolyte layer: Take 0.5g of Li 3 InCl 6 The powder is placed in a mold and cold pressed at a pressure of 360 MPa to form a first-layer ingot. Then, 0.7 g of the powder of Synthesis Example 2 is placed in a mold and cold pressed at a pressure of 360 MPa to form a second-layer ingot, thereby obtaining a double-layer electrolyte ingot.

[0091] Preparation of negative electrode: Indium metal and lithium metal are cut into circles with a diameter of 10 mm using pellet cutters, and then stacked with indium metal on top and lithium metal on the bottom, and cold pressed at a pressure of 20 MPa to form a lithium-indium alloy negative electrode, wherein the weight ratio of lithium metal to indium metal is 2:55.

[0092] Preparation of solid-state battery: Place the lower cover, aluminum foil, positive electrode, solid electrolyte layer, negative electrode, stainless steel gasket, spring and upper cover into the CR-2032 button-type battery in order, with the first layer of the solid electrolyte layer facing the positive electrode and the second layer facing the positive and negative electrodes, and then use a hydraulic press to press the battery at a pressure of 200MPa. The above process is carried out in a glove box filled with argon to ensure that the sample will not be affected by water and oxygen.

[0093] Example 2

[0094] This experiment is similar to the preparation method of the above-mentioned Example 1, except that the second layer of the tablets of Example 2 is obtained by cold pressing of Synthesis Example 5.

[0095] Comparative Example

[0096] This experiment is similar to the preparation method of Example 1 above, except that the second layer of tablets of the comparative example is obtained by cold pressing of the comparative synthesis example.

[0097] The solid-state batteries of the above-mentioned embodiments 1 to 2 and the comparative example were subjected to charge and discharge cycle tests, and the test conditions were: 3 cycles at 0.05C and 50 cycles at 0.1C, wherein the voltage range was 2.2 to 3.7V at 55°C.

[0098] Figure 8 It is a charge and discharge curve of a comparative example. Fig. 9 This is the charge and discharge curve of Example 1. Fig.10 This is the charge and discharge curve of Example 2. Fig.11 The relationship between the number of charge and discharge cycles, discharge capacitance and coulomb efficiency of the comparative example, embodiment 1 and embodiment 2 is shown in FIG. Fig.11 In the figure, the ordinate on the left is the value corresponding to the solid line pattern, and the ordinate on the right is the value corresponding to the dotted line pattern.

[0099] Depend on Figures 5 to 8It can be seen that the first-cycle reversible capacity of the solid-state battery of the comparative example can reach 147.8 mAh / g, and after 50 cycles of charge and discharge, it retains a capacity maintenance rate of 49.3%; the first-cycle reversible capacity of the solid-state battery of Example 1 can reach 157.0 mAh / g, and after 50 cycles of charge and discharge, it retains a capacity maintenance rate of 57.9%; the first-cycle reversible capacity of the solid-state battery of Example 2 can reach 146.5 mAh / g, and after 50 cycles of charge and discharge, it retains a capacity maintenance rate of 69.1%. It can be seen that compared with the comparative example, Examples 1 and 2 have significantly improved capacity maintenance rates, which help to improve the cycle life of solid-state batteries.

[0100] In summary, the solid-state battery of the present invention comprises a solid-state battery having a chemical formula 1 (Li 6+x+y P 1-x-y Si x Ti y S 5-2x-2y B O 2x+2y , where 0≤x≤0.5, 0≤y≤0.5 and x+y>0), the sulfide solid electrolyte can therefore have good ionic conductivity, while improving the chemical stability and voltage stability of the sulfide solid electrolyte, thereby improving the cycle life of the solid-state battery.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A solid-state battery, It is characterized in that include: positive electrode; negative electrode; as well as A solid electrolyte layer is disposed between the positive electrode and the negative electrode, wherein the solid electrolyte layer comprises a sulfide solid electrolyte, and the sulfide solid electrolyte is represented by Chemical Formula 1: [Chemical formula 1] Li 6+x+y P 1-x-y Yes x You y WITH 5-2x-2y No. 2x+2y , In Chemical Formula 1, 0≤x≤0.5, 0≤y≤0.5, and x+y>0.

2. The solid-state battery according to claim 1, It is characterized in that The sulfide solid electrolyte is represented by Chemical Formula 2: [Chemical formula 2] Li 6+x P 1-x Yes x WITH 5-2x No. 2x , In Chemical Formula 2, 0.01≤x≤0.

5.

3. The solid-state battery according to claim 1, It is characterized in that The sulfide solid electrolyte is represented by Chemical Formula 3: [Chemical formula 3] Li 6+y P 1-y You y WITH 5-2y No. 2y , In Chemical Formula 3, 0.01≤y≤0.

5.

4. The solid-state battery according to claim 1, It is characterized in that The solid electrolyte layer has a double-layer structure, and the double-layer structure includes a first layer and a second layer stacked on each other, the first layer is arranged between the negative electrode and the second layer, and the second layer is arranged between the positive electrode and the first layer.

5. The solid-state battery according to claim 4, It is characterized in that The first layer of the solid electrolyte layer includes the sulfide solid electrolyte, and the second layer of the solid electrolyte layer includes a halide solid electrolyte.

6. The solid-state battery according to claim 5, It is characterized in that The halide solid electrolyte is selected from Li 3 InCl 6 , Li 3 AlF 6 , Li 3 GaF 6 , Li 3 YC 6 Li 3 Yb 6 The group formed.

7. The solid-state battery according to claim 1, It is characterized in that The positive electrode includes a positive electrode active material, a solid electrolyte and a conductive additive.

8. The solid-state battery according to claim 7, It is characterized in that The positive electrode active material includes LiNi 0.8 Co 0.1 Mn 0.1 O 2 、LiNi 0.6 Co 0.2 Mn 0.2 O 2 、LiNi 0.6 Co 0.1 Mn 0.3 O 2 、LiNi 0.5 Co 0.2 Mn 0.3 O 2 or a combination thereof.

9. The solid-state battery according to claim 7, It is characterized in that The solid electrolyte in the positive electrode includes a halide solid electrolyte.

10. The solid-state battery according to claim 1, It is characterized in that The negative electrode includes lithium, indium, a lithium-indium alloy or a combination thereof.

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