Stable Poly(3,4‐Dioxythiophene) Radical With Superior Electron and Ion Conductivity as High‐Performance Anode for Lithium‐Ion Battery

Organic radical batteries (ORBs) with small molecule and polymer radicals as electrode materials for lithium‐ion batteries have attracted world‐wide research interest owing to the advantages of the high structural diversity, low cost, and superior sustainability. Herein, in contrast with the traditional doped 3,4‐ethylenedioxythiophene (PEDOT), a new stable non‐doped organic radical polymer poly(3,4‐ethylenedioxythiophene)−3,4‐dioxothiophene (PEDOT‐TO 2 ) with enhanced spin concentration was readily prepared for the first time via one‐step simple reaction. Attributed to the highly reversible interaction between PEDOT‐TO 2 radicals and lithium ion as well as impressive electronic/ionic conductivity, the PEDOT‐TO 2 can deliver outstanding initial specific capacity of 340 mAh g −1 under the current density of 0.1 A g −1 , high capacity retention rate (100% after 3500 cycles at 2.0 A g −1 ), and high rate capability (159.6 mAh g −1 at 10.0 A g −1 ) when evaluated as an anode for Li‐ion battery, which is superior to most previously reported organic radical anodes. Besides, the LiFePO 4 //PEDOT‐TO 2 full cell can show impressive rate performances and cycle stability. The extremely high air stability and superior electrochemical stability contribute to the great potential of PEDOT‐TO 2 as anode material in energy storage, which enriches the library of potential organic electrochemical active electrodes, including cathodes and solid‐state electrolytes.