Abstract
The positive effects of incorporating electrically conductive poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT-PSS) into the negative electrode (NE) of a lithium ion capacitor (LIC) is investigated. The binding material of the NE, styrene-butadiene rubber (SBR), is partially substituted by conductive PEDOT-PSS. The soft carbon NE with 1.0 wt% PEDOT-PSS exhibits enhanced capacity retention of 64% at a current density of 5 C by lowering its electrical and electrochemical charge transfer resistance. The rate capability increased with increasing amounts of PEDOT-PSS, with no variation in the Li+ diffusivity. This improved electrochemical performance of the NE is also reflected in the LIC full-cell configuration. An LIC employing a 1.0 wt% PEDOT-PSS NE delivers 6.6 F at a high current density of 100 C, which is higher than the 6.0 F measured for the LIC with a bare NE. Moreover, the LIC with the 1.0 wt% PEDOT-PSS NE retains 85% of its initial capacitance even after 5000 cycles. These results are mainly attributed to the favourable electrical network formed by the incorporation of PEDOT-PSS into the NE. Thus, we believe that the incorporation of conductive PEDOT-PSS is a viable approach for obtaining high-power LICs.
The partial substitution of a styrene-butadiene rubber (SBR) binder with a small amount of conductive poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT-PSS) is effective for improving the kinetics for Li+ insertion into the soft carbon electrodes for lithium ion capacitors by securing additional electric conduction pathways and reducing the charge transfer resistance at high current densities without significant loss in the binding strength of the electrodes. [Display omitted]
•Incorporation of conductive PEDOT-PSS allows a faster Li+ insertion into soft carbon.•The soft carbon with 1.0 wt% PEDOT-PSS exhibits a capacity retention of 64% at 5 C.•The LIC with 1.0 wt% PEDOT-PSS retains 85% of initial capacitance after 5000 cycles.