Improved stability of lithium-ion battery cathodes using conducting polymer binders

Lithium-nickel-manganese-cobalt oxide (LiNi_xCo_yMn_zO₂) (NCM) has a high specific capacity and is used as a cathode material for Li-ion batteries. However, the poor cycling stability associated with NCM-based cathode composites imposes a challenge for achieving stable cycling performance. Here, we report the use of a conducting polymer as a binder to yield a stable NCM-based cathode composite. Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) was successfully used with a NCM cathode material, resulting in many advantages, such as improved electrical conductivity within the electrode and strong adhesion of the electrode composite on the current collector. With PEDOT:PSS binder, the NCM-based cathodes showed stable cycling performance and an improved capacity retention of ~85% after 100 cycles at 45°C.