Nanocomposite of Conducting Polymer and Li Metal for Rechargeable High Energy Density Batteries.

Abstract

The structure and electrochemical performance of lithium (Li) metal degrade quickly owing to its hostless nature and high reactivity, hindering its practical application in rechargeable high energy density batteries. In order to enhance the electrochemical reversibility of metallic Li, we designed a Li/Li2S-poly(acrylonitrile) (LSPAN) composite foil via a facile mechanical kneading approach using metallic Li and sulfurized poly(acrylonitrile) as the raw materials. The uniformly dispersed Li2S-poly(acrylonitrile) (Li2S-PAN) in a metallic Li matrix buffered the volume change on cycling, and its high Li ion conductivity enabled fast Li ion diffusion behavior of the composite electrode. As expected, the LSPAN electrode showed reduced voltage polarization, enhanced rate capability, and prolonged cycle life compared with the pure Li electrode. It exhibited stable cycling for 600 h with a symmetric cell configuration at 1 mA cm-2 and 1 mA h cm-2, far outperforming the pure metallic Li counterpart (400 h). Also, the LiCoO2||LSPAN full cells with a cathode mass loading of ∼16 mg cm-2 worked stably for 100 cycles at 0.5 C with a high capacity retention of 96.5%, while the LiCoO2||Li full cells quickly failed within only 50 cycles.