Symmetric dual-ion batteries enabled by conjugated p-n fusion microporous polymers

Symmetric all-organic batteries (SAOBs) are promising prospects in realizing low cost, high convenience, and intrinsic safety for energy storage systems. However, the simultaneous pursuit of desired capacities and high voltages poses a significant and challenging hurdle. Herein, we designed and synthesized two conjugated microporous polymers (CMPs) with p (triphenylamine group) -n (thiazole/thiophene groups) fusion bipolar redox-active centers through rational molecular engineering as high-performance electrode materials for SAOBs. The well-designed CMPs are endowed with various merits, such as mainly consisting of high capacity, good cycling stability, and abundant channels for the fast transport of cation/anion. The TPSZ-CMP shows slope charge/discharge curves with an average operating voltage of 2.7 V (vs. Li/Li+) when applied as a cathode and the material contributes a potential of 0.6 V (vs. Li/Li+) in the low voltage range (as an anode), which results in a high cell voltage of up to 1.6 V in the assembled SAOBs. Moreover, owing to the optimized integration of active-unit triphenylamine and thiazole in a stable conjugated backbone, the SAOB exhibits a high discharge capacity of 120 mA h g−1 at 100 mA g−1 with a capacity retention of 85 % after 100 cycles. The introduction of this work may further promote the development of symmetric batteries.