Polypyrrole as an ultrafast organic cathode for dual-ion batteries

Organic electrode materials based on the chemical bond cleavage/recombination working principle usually produce unimpressive reaction kinetics and stability. In this work, polypyrrole (PPy) is investigated as an ultrafast (87% retention at 20 ​A ​g−1) and stable (83% retention across 3000 cycles) cathode material in PPy|graphite dual-ion batteries. The fast intrinsic reaction kinetics, coupled with a capacitance-dominated mechanism, enable PPy to bypass the sluggish chemical bond rearrangement process. Electrochemically induced secondary doping improves the ordered aggregation of polymer chains and thus has a profound impact on anion diffusion and electrical conductivity. The excellent rate capability presented here changes our understanding of organic electrode materials and could prove useful for designing ultrafast rechargeable electrochemical devices.