Polyaniline (PANI) is a promising cathode material for aqueous zinc batteries. However, only half available capacity based on the leucoemeraldine-emeraldine redox reaction can be used. Further oxidation to pernigraniline requires potential exceeding the top voltage limit of aqueous solutions, and the hydrolysis of pernigraniline leads to PANI degradation. Herein, we show that the redox potential of emeraldine-pernigraniline reaction is effectively shifted within electrolyte voltage window by tuning ion activities in electrolyte based on Nernst shift, so that both redox processes of PANI are realized for energy storage in aqueous zinc cells. Meanwhile, the pernigraniline hydrolysis is inhibited with limited water activity in the concentrated electrolyte, and the long-term stability in ensured. The PANI electrode delivers a high capacity of 221 mAh g^-1 at 0.2 A g^-1 and maintains 118 mAh g^-1 at 5 A g^-1 in aqueous zinc batteries. An excellent capacity retention of 96.6% is achieved after 1000 cycles with 99.7% coulombic efficiency. The energy storage processes as well as the active dopants on PANI are identified by a series of characterizations. The work demonstrates an effective strategy to realize energy storage with redox couples outside the voltage window of conventional electrolytes.

聚苯胺（PANI）是一种很有前途的水性锌电池正极材料。然而，只能使用基于无色祖母绿-祖母绿氧化还原反应的一半可用容量。进一步氧化成 pernigraniline 需要电位超过水溶液的最高电压极限，pernigraniline 的水解导致 PANI 降解。在此，我们展示了通过基于能斯特位移调节电解质中的离子活性，在电解质电压窗口内有效地改变了祖母绿-长春花胺反应的氧化还原电位，从而实现了 PANI 的两种氧化还原过程，用于水性锌电池中的能量存储。同时，通过限制浓缩电解质中的水活度，抑制了pernigraniline的水解，确保了长期稳定性。PANI 电极提供 221 mAh g 的高容量^-1在 0.2 A g ^-1和在 5 A g ^-1的水性锌电池中保持 118 mAh g ^-1。1000 次循环后容量保持率高达 96.6%，库仑效率为 99.7%。能量存储过程以及 PANI 上的活性掺杂剂通过一系列表征来确定。这项工作展示了一种有效的策略，可以在常规电解质的电压窗口之外通过氧化还原对实现能量存储。