Tape Casting Preparation And Interface Optimization Of Na₃Zr₂Si₂PO₁₂ Electrolyte Films

Solid-state sodium metal batteries have the advantages of high energy density,high safety and wide working window,and are one of the promising fixed energy storage devices.In solid-state sodium-metal battery systems,the conductivity of the solid electrolyte and the interface between the electrode and the solid electrolyte are critical to the electrochemical performance of the battery.Among many inorganic solid electrolytes,NASICON type Na₃Zr₂Si₂PO₁₂solid electrolyte has high room temperature conductivity,good（electro）chemical stability and mechanical properties.However,Na₃Zr₂Si₂PO₁₂solid electrolyte is difficult to obtain micron-level thickness during the preparation process,resulting in low ionic conductivity,which is difficult to meet the needs of high-performance lightweight energy storage equipment.In addition,due to the poor chemical compatibility between the metal Na anode and the Na₃Zr₂Si₂PO₁₂solid electrolyte,there are problems such as hindered ion/electron transport and interfacial dendrite growth between the two interfaces.Based on this,this paper takes Na₃Zr₂Si₂PO₁₂solid electrolyte as the research object,and uses thin film preparation process optimization and ion doping to obtain high-performance NASICON-type solid electrolyte.The research achievments made in this work are as follows:（1）In view of the problems of low filmization degree and difficulty in large-scale preparation of Na₃Zr₂Si₂PO₁₂solid electrolyte,we used the tape casting process method to regulate the thickness of the prepared film by exploring the process parameters（such as dispersant content,binder content and plasticizer content）.Through Pr³⁺ion doping and thickness control,a solid electrolyte film with a thickness of less than 500μm was prepared with an impedance value lower than 34Ωand an ionic conductivity higher than 5.20×10^-4S cm^-1,and applied to solid-state sodium metal whole battery,showing stable cyclic charge and discharge performance at 0.1 C rate.（2）In view of the poor contact between the interface between the positive electrode and the solid electrolyte of NZSP-Pr,we adopted the solid-liquid synergy strategy to increase the contact area of the electrode/electrolyte,and introduced a gel transition layer between the positive electrode and the electrolyte layer,so that the capacity retention rate of the assembled battery after 70 cycles was 79.2%;By using the method of interface sputtering Au layer and heating static pressure treatment,the problem of negative electrode interface is improved,and the symmetrical battery can be stably cycled for 200 hours at a current density of 0.05 m A cm^-2at room temperature.We scaled up the device and assembled a pouch battery that can light up a small bulb with 3 V LED.（3）In view of the problems of large interface impedance and poor cycle performance caused by the unstable interface contact between Na and Na₃Zr₂Si₂PO₁₂solid electrolyte and Na metal anode,we construct a stable anode/electrolyte interface by room temperature ultrasonic welding technology.By assembling a symmetrical battery,the negative electrode/electrolyte interface impedance is only 28Ω,and the room temperature can be stable for more than 300 hours at a current density of 0.05m A cm^-2.Based on this,the NVP/NZSP-PR/Na-UW full battery assembled by us,after 270 cycles of charge-discharge cycles at room temperature of 0.1 C,has a discharge specific capacity of 103.1 m Ah g^-1and a capacity retention rate of 95.9%...