All-solid-state three-layer electrolyte and preparation method of all-solid-state battery

Abstract

The invention discloses an all-solid-state three-layer electrolyte and a preparation method of an all-solid-state battery. The composite electrolyte has a three-layer structure, and comprises a compact layer in the middle and porous layers located at two sides of the compact layer, the whole preparation process is simple, the preparation cost is low, and no pollution is caused to the environment.The solid electrolyte with the composite structure can effectively improve the interface compatibility of the electrolyte/electrode and reduce the interface impedance, and is beneficial to rapid transmission of metal ions (lithium, sodium, potassium ions and the like) on an interface; the electrolyte comprises the porous layer which is crosslinked with the anode and the cathode, so that the electrolyte has an ion conduction phase and an electron conduction phase at the same time, and the electrode activity and the structural stability can be improved; the effective contact area between the cathode and anode active materials and the electrolyte is increased, so that reaction activation sites are increased, the capacity and rate capability of the solid-state battery are improved, and the electrolyte can be used in all-solid-state lithium, sodium, potassium, Al and Zn plasma solid-state batteries.

Description

technical field [0001] The invention relates to the technical field of solid-state batteries, in particular to a preparation method of an all-solid three-layer electrolyte and an all-solid battery. Background technique [0002] Since most traditional lithium batteries use liquid organic electrolytes, it is impossible to use lithium metal with a higher capacity (3680 mAh / g) as an anode material, nor can a high-voltage material be used as a cathode, so the energy density of the final battery is low and insufficient. To meet the energy demand of current electric vehicles, and there are major safety hazards, there is an urgent need to develop next-generation lithium batteries. [0003] All-solid-state lithium metal batteries are the most promising candidates for next-generation lithium batteries, which not only have higher energy density, but also have higher safety performance. Solid electrolytes have excellent thermal and electrochemical stability, excellent mechanical proper...

AI Technical Summary

Problems solved by technology

However, when the battery undergoes repeated charge-discharge processes, the volume of the electrode material changes, and the volume expansion of the electrode material will cause strain on the interface and then create gaps. The effective contact surface between the solid electrolyte and the electrode material is reduced, which affects the transmission of lithium ions on the interface. Furthermore, the interfacial compatibility between the solid electrolyte and the electrode material itself is poor, resulting in difficulties in the transmission of lithium ions on the interface, and the interfacial impedance between the electrode and the solid electrolyte is greatly increased, thereby affecting the capacity, cycle life, and rate performance of the battery. The above two drawbacks have seriously hindered the further development of all-solid-state lithium batteries.

[0004] Researchers in related technical fields try to improve the interface problems of all-solid-state lithium batteries through various methods. The common treatment methods include interface modification, preparation of interface deposition layer, preparation of polymer interface layer and preparation of ceramic-polymer composite electrolyte. ; The interface modification method mainly uses mechanical grinding and polishing, but it is still difficult to achieve effective point-to-point contact, and the interface compatibility is poor; the method of preparing the interface deposition layer is by means of advanced thin film deposition methods (magnetron sputtering, chemical Vapor phase deposition method), depositing nano-ion conductive films on the interface, such as Au, Al 2 o 3 layer, etc. Although this method can improve the lithium ion transmission rate, it is expensive and not suitable for large-scale production; the method of preparing a polymer interface layer is mainly to prepare a polymer / ceramic / polymer sandwich electrolyte (for example: PEO / Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 / PEO), the main defect of this method is the high cost and the low ionic conductivity of the polymer electrolyte membrane, which affects the rapid transmission of lithium ions on the interface, thereby affecting the overall performance of the battery; the ceramic-polymer composite electrolyte is a combination of ceramics The powder is added to the polymer matrix, and the prepared electrolyte is flexible and can enhance interfacial compatibility, but the mechanical properties of this type of electrolyte are reduced, and there is a danger of lithium dendrite puncture. In addition, due to the polymer electrolyte The ionic conductivity is low, resulting in low ionic conductivity of the resulting solid composite electrolyte (-3 S cm -1 , 25°C)

Therefore, the existing methods have not effectively solved the interface problem in essence, and poor interface compatibility is still a key factor affecting the performance of all-solid-state lithium batteries.

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