Solid-state nanocomposite ionogel electrolyte with in-situ formed ionic channels for uniform ion-flux and suppressing dendrite formation in lithium metal batteries

To keep with the trend of developing safe and high-energy-density lithium (Li) batteries, solid-state electrolytes (SSEs) are sought after to revive Li anodes by enhancing their operation stability. However, SSEs suffer from energy-intensive fabrication processes, complex electrochemical degradations, and interfacial challenges. Herein, a solid-state nanocomposite ionogel electrolyte (n-CIE) composed of in situ generated interface-active silica scaffold and encaged ionic liquid electrolyte (ILE) is proposed to promote the cycling stability of Li metal batteries. The amorphous silica scaffold has extensive mesoporous channels with highly active interfaces, in which disassociated ionic environments could gradually evolve into ionic-type channels. These evolved channels can constrain the movement of large ions via hydrogen bonding and steric charge interaction but allow for fast and homogeneous transport of Li ions (Li+). As a result, the n-CIE has an ionic conductivity of 7.58 x 10-4 S cm -1, and significantly enhanced Li+ transference number of 0.48. In the symmetrical cells using n-CIE, steady plating/stripping without dendrites was observed by tuning ionic fluxes and interfacial engineering, and in full cells with LiCoO2 and LiNi0.8Mn0.1Co0.1O2 cathodes, fairly stable capacity retention of 86.2 and 99.3% for 350 and 75 cycles was achieved respectively. This design of solid electrolytes with unique reticular physi-ochemistry presents an approach to high-performance Li batteries with safe Li metal anodes.

Automated summary

In this study, a solid-state nanocomposite ionogel electrolyte (n-CIE) is proposed to improve the cycling stability of Li metal batteries by utilizing an interface-active silica scaffold and an encaged ionic liquid electrolyte (ILE). The n-CIE exhibits high ionic conductivity and significantly enhanced Li+ transference number, leading to steady plating/stripping without dendrites and stable capacity retention in symmetrical cells and full cells.