Polyanthraquinone as a Reliable Organic Electrode for Stable and Fast Lithium Storage

In spite of recent progress, there is still a lack of reliable organic electrodes for Li storage with high comprehensive performance, especially in terms of long-term cycling stability. Herein, we report an ideal polymer electrode based on anthraquinone, namely, polyanthraquinone (PAQ), or specifically, poly(1,4-anthraquinone) (P14AQ) and poly(1,5-anthraquinone) (P15AQ). As a lithium-storage cathode, P14AQ showed exceptional performance, including reversible capacity almost equal to the theoretical value (260 mA h g^-1; >257 mA h g^-1 for AQ), a very small voltage gap between the charge and discharge curves (2.18-2.14=0.04 V), stable cycling performance (99.4 % capacity retention after 1000 cycles), and fast-discharge/charge ability (release of 69 % of the low-rate capacity or 64 % of the energy in just 2 min). Exploration of the structure-performance relationship between P14AQ and related materials also provided us with deeper understanding for the design of organic electrodes. No compromises! An ideal polymer electrode based on anthraquinone, poly(1,4-anthraquinone) (P14AQ), was applied as a cathode for rechargeable lithium batteries (see picture). Unrivaled by other organic electrodes, it showed exceptional performance, including stable cycling (99.4 % capacity retention after 1000 cycles) and fast discharge/charge ability (releasing 69 % of the low-rate capacity or 64 % of the energy in just 2 min).