Carbon Dots Evoked Li Ion Dynamics for Solid State Battery.

Solid composite electrolyte-based Li battery is viewed as one of the most competitive system for the next generation batteries; however, it is still restricted by sluggish ion diffusion. Fast ion transport is a characteristic of the polyethylene oxide (PEO) amorphous phase, and the mobility of Li+ is restrained by the coordination interaction within PEO and Li+ . Herein, the design of applying functionalized carbon dots (CDs) with abundant surface features as fillers is proposed. High ionic conductivity is achieved in the CD-based composite electrolytes resulting from enhanced ion migration ability of polymer segments and mobility of Li+ . Specially, the optimum effect with nitrogen and sulfur co-doped carbon dots (NS-CD) is a consequence of strong interaction between edge-nitrogen/sulfur in NS-CD and Li+ . Solid-state nuclear magnetic resonance results confirm that more mobile Li+ is generated. Moreover, it is observed that lithium dendrite is suppressed compared to PEO electrolyte associated with reinforced mechanical properties and high transference number. The corresponding all-solid-state batteries, with the cathode of LiFePO4 or high voltage NCM523, exhibit long cycling life and excellent rate performances. It is a novel strategy to achieve high ionic conductivity composite electrolyte with uniform lithium deposition and provides a new direction to the mechanism of fast Li+ movement.