Improved Cycling Stability of Lithium Electrodes in Rechargeable Lithium Batteries

Poly(3,4-ethylenedioxythiophene)-co-poly(ethylene glycol) copolymer was coated onto lithium metal as a protective layer. The thin conductive polymer with strong adhesion to the lithium electrode suppressed the corrosion of the lithium metal and stabilized the interface of the lithium electrode in prolonged contact with the organic electrolyte. The conductive polymer coating on the lithium metal caused the capacity retention of the Li/LiCoO2 cell to increase from 9.3% to 87.3% after 200 cycles compared to the cell with the pristine lithium electrode. The improvement in cycling stability is attributed to the conductive polymer coating suppressing lithium dendrite growth and the deleterious reaction between the lithium electrode and the electrolyte solution during cycling.