Ion-electron hybrid conductive metal sodium negative electrode and preparation method thereof

Abstract

The invention discloses an ion-electron hybrid conductive metal sodium negative electrode. The metal sodium negative electrode consists of a solid electrolyte and metal sodium, and is formed by melting and mixing the solid electrolyte powder and the metal sodium, wherein the metal sodium forms a matrix of the metal sodium negative electrode, the solid electrolyte constructs a Na <+> conduction network in the metal sodium matrix, and the solid electrolyte is NZSP particles of which the surfaces are coated with SnO2, and the NZSP refers to Na <3 + x> Zr2Si <2 + x> P<1-x>O12. The invention also discloses a preparation method of the sodium negative electrode. The preparation method mainly comprises three processes of synthesizing the solid electrolyte, modifying the surface of the solid electrolyte and melting and mixing the solid electrolyte and metal sodium to prepare the electrode. The metal sodium negative electrode prepared by the method has excellent cycling stability and relativelylower electrochemical impedance, and shows high cycling stability and relatively lower capacity attenuation in a total battery test.

Description

technical field [0001] The invention relates to a sodium ion battery electrode material and a preparation method thereof, belonging to the field of energy materials. Background technique [0002] With the rapid development of the electric energy storage market, the research and development of energy storage systems and the search for advanced methods to increase energy density and reduce manufacturing costs have become important issues of global concern. Among many new battery systems, sodium metal batteries have attracted extensive attention due to their similar working principles to lithium-ion batteries, high energy density, and abundant sodium reserves in the earth's crust, and have become an important development direction in the field of electrochemical energy storage technology. . The electrode material is the carrier of the charge storage of the secondary battery and determines the overall performance of the battery. Metallic sodium has a high theoretical capacity ...

AI Technical Summary

Problems solved by technology

[0005] However, in these existing technologies, there are still some shortcomings, mainly: 1. The strategy of constructing artificial SEI can improve the cycle stability of metallic sodium to a certain extent under the condition of low current and low capacity charge and discharge

However, since the deposition and dissolution reactions of Na only occur on the surface of the electrode, the lower layer of the artificial SEI undergoes a huge volume change during cycling, and the practical discharge capacity (>3 mAh cm -2 ) interface of the lower electrode cannot remain stable

2. Although the higher specific surface area of ​​the three-dimensional current collector is beneficial to reduce the local current density, the open pore structure inside will also lead to more electrolyte exposure, which will intensify the consumption of active sodium and electrolyte

In addition, since the reaction still occurs on the surface of metallic Na, the dendrite growth phenomenon caused by the non-uniform SEI cannot be avoided after increasing the current density.

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