Improved electrochemical properties of cathode material LiMn2O4 with conducting polymer binder

Novel LiMn2O4 based cathode material with eco-friendly water-based binder consisting of conducting polymer poly-3,4-ethylenedioxythiopene/polystyrene sulfonate (PEDOT:PSS) dispersion and carboxymethylcellulose (СМС) is proposed. The morphology and the structure of the composite materials were investigated by X-ray diffraction, scanning electron microscopy, EDX analysis and XPS. The electrochemical properties of modified cathode materials of different composition were investigated by cyclic voltammetry, galvanostatic charge-discharge and by electrochemical impedance spectroscopy. The results were compared with those obtained for conventional PVDF-bound LiMn2O4 material. It was shown that the material with optimal composition consisting of 86 wt.% of LiMn2O4, 10 wt.% of carbon black and 4 wt.% of conducting polymer binder exhibited good rate capability with discharge capacity 126 mAh g−1 (at 0.2 C, normalized by LiMn2O4 mass) and 75 mAh g−1 at 10 C as well as good cycling stability at 1 C (less than 5% decay after 200 cycles). These functional characteristics were markedly better than for PVDF-bound LiMn2O4 material. The electrochemical impedance spectra reveal the significant decrease of interfacial resistance and an increase of apparent diffusion coefficients for LiMn2O4 cathode material with conducting polymer binder, which favor improved functional characteristics.