NASICON-type Electrolytes For Interface Optimization And Application In Solid-state Sodium Batteries

Sodium metal anodes with a high theoretical energy density(1165 m Ah·g^–1)and low potential（-2.71 V）are attracting a lot of attention.However,in the conventional liquid electrolyte system,its development is often affected by problems such as interfacial side reactions and dendrite growth.All-solid-state sodium ion batteries have attracted extensive attention in recent years due to its high energy density and high safety,which can effectively avoid the above problems.However,there still exists some problems such as the high interfacial resistance and sodium dendrite growth.Therefore,how to effectively reduce the interfacial resistance between sodium metal and NASICON electrolyte is the primary problem that needs to be solved for the development of NASICON-based solid-state sodium ion batteries.To address the above issues,the following work has been done.1)To investigate the effect of different metal element modifications on the wettability and activity of the sodium/NASICON interface,a combination of thermodynamic calculations and experiments was performed.It was the alloy reaction between lead and tin and sodium to form solid solution that improved the wettability and activity of the sodium/NASICON interface after calculations and experiments.2)To address the problems of poor wettability,uneven and slow charge transfer at the sodium/NASICON interface,lead layer was introduced on the surface of the NASICON electrolyte to regulate it.It’s the formation of sodium-lead solid solution that improved the interfacial wettability and promoted the uniform and rapid charge transfer.The symmetric cell assembled with this electrolyte was able to cycle stably at a current density of 0.1m A·cm^-2for over 1400 h at 60℃.3)To address the problems of dendrite formation and volume fluctuation of negative sodium during the cell cycle,a three-dimensional ion/electron hybrid layer is artificially designed on the surface of NASICON electrolyte to regulate it,which can prevent the direct contact between the sodium and the electrolyte to avoid dendrite generation and provide space for the volume variation of the negative sodium.The symmetric cell assembled with this electrolyte can stable cycle over 2000 h at a current density of 0.2 m A·cm^-2at room temperature.Figure 47;Table 2;Reference 79...