Secondary battery

Abstract

A secondary battery. The secondary battery is a sodium secondary battery or a lithium secondary battery, and comprises a positive electrode, a negative electrode, and an electrolyte layer. The negative electrode comprises a conductive current collector, a negative electrode active material, and a non-alkali metal monovalent ion conductor, wherein non-alkali metal ions in the non-alkali metal monovalent ion conductor are replaced with sodium ions or lithium ions during battery formation, thereby forming a metal layer at an interface between the negative electrode and the electrolyte layer. The secondary battery, such as an alkali metal secondary battery, is more stable under ambient conditions, easy to prepare and cheap, and has improved rate performance and greatly prolonged battery cycle life.

Description

Secondary batteries Technical Field

[0001] This invention belongs to the field of energy storage technology. Specifically, this invention relates to a secondary battery. More specifically, this invention relates to an alkali metal secondary battery. Background Technology

[0002] Alkali metal lithium or sodium secondary batteries, as a form of chemical energy storage, are characterized by high energy density and long lifespan. With industry development, the solid-state electrolyte and the high specific capacity of the negative electrode have become the development direction for secondary batteries.

[0003] Sulfide and halide solid electrolytes are considered the preferred materials for future solid-state batteries due to their excellent properties such as high ionic conductivity. However, the preparation environment for alkaline ionic sulfides is demanding, and they are more sensitive to moisture than other cation-based electrolytes. Furthermore, since solid electrolytes themselves lack electronic conductivity, a relatively high proportion of electrolyte (typically >20% by weight) is required in the electrodes to ensure continuous ion transport in order to guarantee stable battery operation.

[0004] Currently, inorganic solid-state electrolytes can be classified into lithium superionic conductors (LISICON), sodium superionic conductors (NASICON), argyrodite, perovskite, antiperovskite, and garnet types. Sulfide solid-state electrolytes have attracted significant attention due to their high ionic conductivity; for example, Li... + Ionic conductors: LiPS5Cl, Li3PS4, LiSnS4, Li3BO3, Li4SiO4, Li7P3S 11 And sodium ion conductor Na3PS 4、 Na3SbS4, Na 11 Sn2SbS 12 .

[0005] Cu + and Ag + Early ionic conductor materials were primarily solid electrolytes that were extensively studied. Commonly used materials included Cu6PS5X and Ag6PS5X (X = Cl, Br, I), which were constructed through homogeneous ion transport. + and Ag +Secondary batteries. Relevant research can be found in JP49007169-A, CN104851473-A, and Journal of Non-Crystalline Solids, 2019, 521, 119476; Journal of Physics and Chemistry of Solids, 2003, 64, 1261; or Research Progress on Sodium Ion Sulfide Solid Electrolytes, Energy Storage Science and Technology, 2020, 9, 1266.

[0006] Therefore, there is an urgent need for a solid electrolyte that can be used in alkali metal secondary batteries, which is more stable under environmental conditions, easier to prepare, requires only a small amount to adapt to the volume effect of the negative electrode material, and can significantly improve the cycle life of alkali metal secondary batteries.

[0007] Invention Overview

[0008] The purpose of this invention is to provide a secondary battery, especially an alkali metal secondary battery, which is more stable under environmental conditions, easier to prepare, cheaper, has improved rate performance, and significantly improved cycle life.

[0009] The above-mentioned objective of the present invention is achieved through the following technical solution.

[0010] This invention provides a secondary battery, which is a sodium secondary battery or a lithium secondary battery, comprising a positive electrode, a negative electrode, and an electrolyte layer, wherein:

[0011] The negative electrode includes a conductive current collector, a negative electrode active material, and a non-alkali metal monovalent ion conductor, wherein the non-alkali metal ions in the non-alkali metal monovalent ion conductor are replaced by sodium ions or lithium ions during the battery formation process, thereby forming a metal layer at the interface between the negative electrode and the electrolyte layer.

[0012] The inventors of this application unexpectedly discovered that when a battery is prepared using non-alkali metal copper and / or silver ion conductors as the initial electrolyte in the negative electrode, copper and / or silver ions can be replaced by alkali metal ions during the battery formation process, thereby forming a solid electrolyte that conducts lithium or sodium ions in situ. The copper and / or silver layer formed at the interface between the electrolyte and the negative electrode during the formation process can homogenize the electron or ion transport in the negative electrode, inhibit the growth of lithium or sodium dendrites, and increase the critical current density for the operation of the alkali metal secondary battery.

[0013] Preferably, in the secondary battery of the present invention, the non-alkali metal monovalent ion conductor is capable of ionizing Cu. + Compounds of ions and / or capable of ionizing Ag + Compounds containing ions.

[0014] Preferably, in the secondary battery of the present invention, the non-alkali metal monovalent ion conductor is selected from Cu6PS5Cl, Cu6PS5Br, Cu6PS5I, Cu3PS4, and Cu7P3S. 11 , CuCl, Cu2SO4, Ag6PS5Cl, Ag6PS5Br, Ag6PS5I, Ag3PS4, Ag7P3S 11 One or more of AgCl and AgI.

[0015] Preferably, in the secondary battery of the present invention, the weight ratio of the non-alkali metal monovalent ion conductor to the negative electrode active material is 1:(9-99).

[0016] Preferably, in the secondary battery of the present invention, the surface of the conductive current collector is provided with an inactive conductive coating.

[0017] Preferably, in the secondary battery of the present invention, the inactive conductive coating is composed of one or more materials selected from carbon-based materials, alloy materials and metallic materials.

[0018] Preferably, in the secondary battery of the present invention, when the secondary battery is a sodium secondary battery, the negative electrode active material includes one or more materials selected from hard carbon, soft carbon and antimony oxide; and the conductive current collector includes aluminum foil or carbon-coated aluminum foil.

[0019] Preferably, in the secondary battery of the present invention, when the secondary battery is a lithium secondary battery, the negative electrode active material includes one or more materials selected from graphite, hard carbon, soft carbon, silicon-carbon, silicon and silicon-tin based materials; and the conductive current collector includes copper foil or carbon-coated copper foil.

[0020] Preferably, in the secondary battery of the present invention, when the secondary battery is a sodium secondary battery, the positive electrode comprises one or more positive electrode active materials selected from sodium cobaltate, sodium manganate, sodium ferrite, sodium vanadium phosphate, and Prussian white.

[0021] Preferably, in the secondary battery of the present invention, when the secondary battery is a lithium secondary battery, the positive electrode comprises one or more positive electrode active materials selected from NCM ternary positive electrode materials, NCA ternary positive electrode materials, LFP lithium iron phosphate, LMO lithium manganese oxide, LNMO lithium nickel manganese oxide, lithium-rich manganese-based positive electrode materials, and lithium sulfide.

[0022] Preferably, in the secondary battery of the present invention, when the secondary battery is a sodium secondary battery, the electrolyte layer comprises a mixture selected from Na6PS5Cl, Na6PS5Br, Na6PS5I, Na3PS4, and Na7P3S. 11 One or more electrolyte materials.

[0023] Preferably, in the secondary battery of the present invention, when the secondary battery is a lithium secondary battery, the electrolyte layer comprises a mixture selected from Li6PS5Cl, Li6PS5Br, Li6PS5I, Li3PS4, and Li7P3S. 11 One or more electrolyte materials.

[0024] Preferably, in the secondary battery of the present invention, the electrolyte layer comprises a non-alkali metal monovalent ion conductor. More preferably, the non-alkali metal monovalent ion conductor is selected from Cu6PS5Cl, Cu6PS5Br, Cu6PS5I, Cu3PS4, and Cu7P3S. 11 , CuCl, Cu2SO4, Ag6PS5Cl, Ag6PS5Br, Ag6PS5I, Ag3PS4, Ag7P3S 11 One or more of AgCl and AgI.

[0025] In some specific embodiments of the present invention, the non-alkali metal monovalent ion conductor of the present invention is prepared and composited in the negative electrode by methods such as grinding, liquid phase mixing, chemical and physical deposition, and there are no particular limitations.

[0026] The working principle of the secondary battery of the present invention is as follows:

[0027] After the positive electrode, electrolyte layer, and negative electrode are stacked and pressed together, they are charged. In the negative electrode, non-alkali metal ions such as copper and / or silver ions in the non-alkali metal ion conductor are replaced by alkali metal lithium and / or sodium ions. Copper and / or silver ions are deposited at the interface between the electrolyte and the negative electrode material, and lithium and / or sodium ions continue to react with the negative electrode active material.

[0028] The present invention has the following beneficial effects:

[0029] The secondary battery of this invention exhibits higher stability under atmospheric conditions and can increase the capacity utilization of the negative electrode active material even with extremely low electrolyte content (i.e., very low content of non-alkali metal monovalent ion conductor). This is mainly because, through an electrochemical process, Li₂ is released from the lithium- or sodium-containing positive electrode. + Or Na + Replaces Cu in copper and / or silver ion conductors + and / or Ag + This forms an alternative electrolyte layer, which in turn induces Cu and / or Ag to deposit at the interface between the electrolyte and the negative electrode, forming an interface layer that improves electronic conductivity and inhibits the formation of lithium or sodium dendrites.

[0030] Brief description of the attached figures

[0031] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings, wherein:

[0032] Figure 1 shows a scanning electron microscope image of the negative electrode cross-section of the interface layer constructed by the electrochemical method in Example 3 of the present invention.

[0033] Figure 2 shows a scanning electron microscope image of the negative electrode cross section in Comparative Example 2;

[0034] Figure 3 shows the charging curve of the secondary battery prepared in Example 3 of the present invention at a current density of 0.1C rate;

[0035] Figure 4 shows the charging curve of the secondary battery prepared in Comparative Example 2 at a current density of 0.1C rate.

[0036] The best way to implement an invention

[0037] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0038] Example 1

[0039] In a dry environment with an ambient dew point of -40℃, 10 mg of Na6PS5Cl was weighed and placed in a 10 mm diameter PTFE sleeve, and kept under a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. NaCoO2 and Na6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 30 mg of this mixture was weighed and placed on one side of the electrolyte sheet, and kept under a pressure of 360 MPa for 10 min. Hard carbon and AgI were mixed evenly in a mortar at a mass ratio of 98:2 to form a composite negative electrode. 30 mg of this mixture was weighed and placed on the other side of the electrolyte sheet. An Al current collector was then attached to the surface, and the mixture was kept under a pressure of 100 MPa for 5 min. The resulting secondary battery is denoted as a1.

[0040] Example 2

[0041] In a dry environment with an ambient dew point of -40℃, 10 mg of Li6PS5Cl was weighed and placed in a 10 mm diameter PTFE sleeve, and kept under a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. LiNi 0.8 Co 0.1 Mn 0.1 O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 30 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. Graphite and AgI were mixed evenly in a mortar at a mass ratio of 98:2 to form a composite negative electrode. 30 mg of this mixture was placed on the other side of the electrolyte sheet, and a Cu current collector was then attached to the surface. The mixture was kept under a pressure of 100 MPa for 5 min. The resulting secondary battery is denoted as a2.

[0042] Example 3

[0043] In a dry environment with an ambient dew point of -40℃, 10 mg of Li6PS5Cl was weighed and placed in a 10 mm diameter PTFE sleeve, and kept under a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. LiNi 0.8 Co 0.1 Mn 0.1 O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 30 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. Silicon and Cu6PS5Cl were mixed evenly in a mortar at a mass ratio of 98:2 to form a composite negative electrode. 30 mg of this mixture was placed on the other side of the electrolyte sheet, and a Cu current collector was then attached to the surface. The mixture was kept under a pressure of 100 MPa for 5 min. The resulting secondary battery is denoted as a3.

[0044] Figure 1 shows a scanning electron microscope (SEM) image of the negative electrode interface constructed by the electrochemical method in Example 3 of the present invention. The SEM image in Figure 1a shows an intermediate layer at the interface between the electrolyte and Si. The elemental EDS spectra of Si, S, and Cu in Figures 1b)-1d) further show that, due to the presence of Li on the positive electrode side… + The Cu in Cu6PS5Cl at the negative electrode migrates towards the negative electrode side, causing Cu to migrate towards the negative electrode side. + Upon leaving the S-containing electrolyte portion, a Cu-enriched layer forms at the interface through reduction. The original Cu6PS5Cl transforms into Li6PS5Cl, resulting in the disappearance of the Cu signal in EDS. The Cu at the interface significantly improves interfacial contact and electron transport.

[0045] Figure 3 shows the charging curve of the secondary battery prepared in Example 3 of the present invention at a rate of 0.1C. The battery charging and discharging curves are smooth and normal, the coulombic efficiency is normal, and the reversible specific capacity of the battery is 195mAh / g.

[0046] Example 4

[0047] In a dry environment with an ambient dew point of -40℃, 10 mg of Li6PS5Cl was weighed and placed in a 10 mm diameter PTFE sleeve, and kept under a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. LiNi 0.8 Co 0.1 Mn 0.1 O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 30 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. Silicon and Ag7P3S11 were mixed evenly in a mortar at a mass ratio of 97:3 to form a composite negative electrode. 30 mg of this mixture was placed on the other side of the electrolyte sheet, and a Cu current collector was then attached to the surface. The mixture was kept under a pressure of 100 MPa for 5 min. The resulting secondary battery is denoted as a4.

[0048] Example 5

[0049] In a dry environment with an ambient dew point of -40℃, 10 mg of Na6PS5Cl was weighed and placed in a 10 mm diameter PTFE sleeve, and kept under a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. NaCoO2 and Na6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 30 mg of this mixture was weighed and placed on one side of the electrolyte sheet, and kept under a pressure of 360 MPa for 10 min. Hard carbon and Ag6PS5Br were mixed evenly in a mortar at a mass ratio of 95:5 to form a composite negative electrode. 30 mg of this mixture was weighed and placed on the other side of the electrolyte sheet. An Al current collector was then attached to the surface, and the mixture was kept under a pressure of 100 MPa for 5 min. The resulting secondary battery is denoted as a5.

[0050] Example 6

[0051] In a dry environment with an ambient dew point of -40℃, 10 mg of Li6PS5Cl was weighed and placed in a 10 mm diameter PTFE sleeve, and kept under a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. LiNi 0.8 Co 0.1 Mn 0.1 O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 30 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 minutes. Graphite and Cu7P3S... 11 Mix the electrolytes in a mortar at a mass ratio of 95:5 to form a composite negative electrode. Weigh 30 mg of the electrolyte and place it on the other side of the electrolyte sheet. Maintain the pressure at 360 MPa for 100 min. Then attach a Cu current collector to the surface and maintain the pressure at 10 MPa for 5 min. The resulting secondary battery is denoted as a6.

[0052] Example 7

[0053] In a dry environment with an ambient dew point of -40℃, 10 mg of Cu6PS5Cl was weighed and placed in a 10 mm diameter PTFE sleeve, and kept under a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. LiNi 0.8 Co 0.1 Mn 0.1O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 30 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. Graphite and Cu6PS5I were mixed evenly in a mortar at a mass ratio of 95:5 to form a composite negative electrode. 30 mg of this mixture was placed on the other side of the electrolyte sheet, and a Cu current collector was then attached to the surface. The mixture was kept under a pressure of 100 MPa for 5 min. The resulting secondary battery is denoted as a7.

[0054] Example 8

[0055] In a dry environment with an ambient dew point of -40℃, 10 mg of Na6PS5Cl was weighed and placed in a 10 mm diameter PTFE sleeve, and kept under a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. NaCoO2 and Na6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 30 mg of this mixture was weighed and placed on one side of the electrolyte sheet, and kept under a pressure of 360 MPa for 10 min. Hard carbon and Ag3PS4 were mixed evenly in a mortar at a mass ratio of 98:2 to form a composite negative electrode. 30 mg of this mixture was weighed and placed on the other side of the electrolyte sheet. An Al current collector was then attached to the surface, and the mixture was kept under a pressure of 100 MPa for 5 min. The resulting secondary battery is denoted as a8.

[0056] Example 9

[0057] In a dry environment with an ambient dew point of -40℃, 10 mg of Na6PS5Cl was weighed and placed in a 10 mm diameter PTFE sleeve, and kept under a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. NaCoO2 and Na6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 30 mg of this mixture was weighed and placed on one side of the electrolyte sheet, and kept under a pressure of 360 MPa for 10 min. Hard carbon and Ag6PS5Cl were mixed evenly in a mortar at a mass ratio of 95:5 to form a composite negative electrode. 30 mg of this mixture was weighed and placed on the other side of the electrolyte sheet. An Al current collector was then attached to the surface, and the mixture was kept under a pressure of 100 MPa for 5 min. The resulting secondary battery is denoted as a9.

[0058] Example 10

[0059] In a dry environment with an ambient dew point of -40℃, 10 mg of Li6PS5Cl was weighed and placed in a 10 mm diameter PTFE sleeve, and kept under a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. LiNi 0.8 Co 0.1 Mn 0.1O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 30 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. Silicon and Cu6PS5Br were mixed evenly in a mortar at a mass ratio of 9:1 to form a composite negative electrode. 30 mg of this mixture was placed on the other side of the electrolyte sheet, and a Cu current collector was then attached to the surface. The mixture was kept under a pressure of 100 MPa for 5 min. The resulting secondary battery is denoted as a10.

[0060] Example 11

[0061] In a dry environment with an ambient dew point of -40℃, 10 mg of Li6PS5Cl was weighed and placed in a 10 mm diameter PTFE sleeve, and kept under a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. LiNi 0.8 Co 0.1 Mn 0.1 O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 30 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. Silicon and Cu2SO4 were mixed evenly in a mortar at a mass ratio of 97:3 to form a composite negative electrode. 30 mg of this mixture was placed on the other side of the electrolyte sheet, and a Cu current collector was then attached to the surface. The mixture was kept under a pressure of 100 MPa for 5 min. The resulting secondary battery is denoted as a11.

[0062] Comparative Example 1

[0063] In a dry environment with an ambient dew point of -40℃, 10 mg of Li6PS5Cl was weighed and placed in a 10 mm diameter PTFE sleeve, and kept under a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. LiNi 0.8 Co 0.1 Mn 0.1 O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 30 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. Graphite and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 95:5 to form a composite negative electrode. 30 mg of this mixture was placed on the other side of the electrolyte sheet, and a Cu current collector was then attached to the surface. The mixture was kept under a pressure of 100 MPa for 5 min. The resulting secondary battery is denoted as b1.

[0064] Comparative Example 2

[0065] In a dry environment with an ambient dew point of -40℃, 10 mg of Li6PS5Cl was weighed and placed in a 10 mm diameter PTFE sleeve, and kept under a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. LiNi 0.8 Co0.1 Mn 0.1 O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 30 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. Silicon and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 98:2 to form a composite negative electrode. 30 mg of this mixture was placed on the other side of the electrolyte sheet, and a Cu current collector was then attached to the surface. The mixture was kept under a pressure of 100 MPa for 5 min. The resulting secondary battery is denoted as b2.

[0066] Figure 2 shows a scanning electron microscope (SEM) image of the negative electrode interface in Comparative Example 2 of the present invention. The SEM image in Figure 2a) shows good contact between the electrolyte and the interface. The EDS spectra of Si and S elements in Figures 2b) and 2c) further indicate that there is no intermediate interface layer, and the interfaces between the Si and S regions are clearly distinguishable.

[0067] Figure 4 shows the charging curve of the secondary battery prepared in Comparative Example 2 of the present invention at a 0.1C rate. The battery charge-discharge curve is normal, but due to the low electrolyte content, the reversible specific capacity of the battery is only 67 mAh / g.

[0068] Comparative Example 3

[0069] In a dry environment with an ambient dew point of -40℃, 10 mg of Li6PS5Cl was weighed and placed in a 10 mm diameter PTFE sleeve, and kept under a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. LiNi 0.8 Co 0.1 Mn 0.1 O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 30 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. Silicon and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite negative electrode. 30 mg of this mixture was placed on the other side of the electrolyte sheet, and a Cu current collector was then attached to the surface. The mixture was kept under a pressure of 100 MPa for 5 min. The resulting secondary battery is denoted as b3.

[0070] Secondary battery short circuit test

[0071] The secondary batteries of Examples 1-11 and Comparative Examples 1-3 were subjected to constant current charging at 2 mA / cm² in a dry environment with an ambient dew point of -40°C and an ambient temperature of 25°C. 2 Charge the battery at a current density for 1 hour, and observe the voltage of the secondary battery. If the voltage is 0V, it is determined to be in a short-circuit state.

[0072] First reversible specific capacity and 100-cycle capacity retention test

[0073] In a dry environment with an ambient dew point of -40°C, the secondary battery of the example was first subjected to 0.1C pre-charge-discharge formation at a test pressure of 100MPa and an environment of 60°C, and the initial reversible specific capacity was recorded. Subsequently, a 0.2C low-rate charge-discharge cycle was performed, and the capacity retention rate at the 100th cycle was calculated based on the ratio of the discharge capacity at the first 0.2C cycle to that at the 100th cycle.

[0074] Table 1. First reversible capacity and capacity retention after 100 cycles for the examples and comparative cases.

[0075] Note: The term "electrolyte content in the negative electrode (wt%)" in Table 1 refers to the weight percentage of the non-alkali metal monovalent ion conductor based on the total weight of the electrolyte (i.e., non-alkali metal monovalent ion conductor) and the negative electrode active material.

[0076] Table 1 shows that the alkali metal secondary battery of the present invention can effectively exert the reversible capacity of the battery with a very low content (5%). A comparison of a3, b2, and b3 shows that if a conventional electrolyte such as Li6PS5Cl is added to the negative electrode, its content needs to be increased to a very high percentage (e.g., to 30%) to achieve a high initial capacity and subsequent cycle stability.

[0077] Table 2 High Current Short Circuit Conditions in Examples and Comparative Cases

[0078] Table 2 shows that the alkali metal secondary battery of the present invention can improve the negative electrode rate and exhibits advantages in short-circuit resistance during charging.

Claims

1. A secondary battery, said secondary battery being a sodium secondary battery or a lithium secondary battery, comprising a positive electrode, a negative electrode, and an electrolyte layer, wherein: The negative electrode includes a conductive current collector, a negative electrode active material, and a non-alkali metal monovalent ion conductor, wherein the non-alkali metal ions in the non-alkali metal monovalent ion conductor are replaced by sodium ions or lithium ions during the battery formation process, thereby forming a metal layer at the interface between the negative electrode and the electrolyte layer.

2. The secondary battery according to claim 1, wherein, The non-alkali metal monovalent ion conductor is capable of ionizing Cu. + Compounds of ions and / or capable of ionizing Ag + Compounds containing ions.

3. The secondary battery according to claim 1, wherein, The non-alkali metal monovalent ionic conductor is selected from Cu6PS5Cl, Cu6PS5Br, Cu6PS5I, Cu3PS4, and Cu7P3S. 11 , CuCl, Cu2SO4, Ag6PS5Cl, Ag6PS5Br, Ag6PS5I, Ag3PS4, Ag7P3S 11 One or more of AgCl and AgI.

4. The secondary battery according to claim 1, wherein, The weight ratio of the non-alkali metal monovalent ion conductor to the negative electrode active material is 1:(9-99).

5. The secondary battery according to claim 1, wherein, The surface of the conductive current collector is provided with an inactive conductive coating.

6. The secondary battery according to claim 5, wherein, The inactive conductive coating is composed of one or more materials selected from carbon-based materials, alloy materials, and metallic materials.

7. The secondary battery according to claim 1, wherein, The secondary battery is a sodium secondary battery, and the negative electrode active material includes one or more materials selected from hard carbon, soft carbon, and antimony oxide; or The secondary battery is a lithium secondary battery, and the negative electrode active material includes one or more materials selected from graphite, hard carbon, soft carbon, silicon-carbon, silicon, and silicon-tin based materials.

8. The secondary battery according to claim 1, wherein, The secondary battery is a sodium secondary battery, and the positive electrode comprises one or more positive electrode active materials selected from sodium cobaltate, sodium manganate, sodium ferrite, sodium vanadium phosphate, and Prussian white; or The secondary battery is a lithium secondary battery, and the positive electrode comprises one or more positive electrode active materials selected from NCM ternary positive electrode materials, NCA ternary positive electrode materials, LFP lithium iron phosphate, LMO lithium manganese oxide, LNMO lithium nickel manganese oxide, lithium-rich manganese-based positive electrode materials, and lithium sulfide.

9. The secondary battery according to claim 1, wherein, The secondary battery is a sodium secondary battery, and the electrolyte layer comprises a mixture selected from Na6PS5Cl, Na6PS5Br, Na6PS5I, Na3PS4, and Na7P3S. 11 One or more electrolyte materials; or The secondary battery is a lithium secondary battery, and the electrolyte layer comprises substances selected from Li6PS5Cl, Li6PS5Br, Li6PS5I, Li3PS4, and Li7P3S. 11 One or more electrolyte materials.

10. The secondary battery according to any one of claims 1 to 9, wherein, The electrolyte layer comprises the non-alkali metal monovalent ion conductor, preferably selected from Cu6PS5Cl, Cu6PS5Br, Cu6PS5I, Cu3PS4, and Cu7P3S. 11 , CuCl, Cu2SO4, Ag6PS5Cl, Ag6PS5Br, Ag6PS5I, Ag3PS4, Ag7P3S 11 One or more of AgCl and AgI.

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