Nano-encapsulation of graphite-based anodes by a novel polymer electrolyte and its influence on C-rate performances of Li-ion batteries

Abstract

A unique approach for improving the C-rate (charge/discharge) performances of lithium-ion batteries has been presented, which is based on the nano-encapsulation of graphite (MCMB, mesophase microbead) anodes by the cPVA (cyanoethyl polyvinylalcohol)-gel polymer electrolyte. Through this new process, the gel polymer electrolyte can effectively cover the MCMB surface at nanometer-scaled thickness. The novel morphology of the cPVA coating layer and its high polar -CN groups are considered as key factors to modify the MCMB surface to be electrolyte-philic. This increased polarity of MCMB is expected to allow the favorable impregnation of liquid electrolytes into the pores of the anode and finally contribute to the superior ionic conduction at the faster charge/discharge rates. In addition, it has been demonstrated that the nano-encapsulation of MCMB effectively suppressed the lithium-metal dendrite growth on the charged anode.