The development of low-cost electrode with high capacity and long cycle-life is an essential issue for energy storage devices. Herein a unique nanostructured tetragonal LiMn₂O₄ (TLMO) electrode exhibiting mixed pseudocapacitor and battery behaviors in Li ion-containing aqueous electrolytes is derived via a novel in-situ low-temperature ion-exchange method from nanocrystalline ZnMn₂O₄. The complementary actions between the pseudocapacitance and battery properties enable TLMO to substantially outperform, in terms of the combination of high capacity, long cycle stability and suppressed self-discharge, its counterparts having only either one of the electrochemical behaviors, along with many other notable pseudocapacitive materials. The phase transformation mechanism during the ion-exchange process and charge-storage mechanisms are revealed using operando/in situ synchrotron X-ray analyses. This study may open up a new design concept in charge-storage electrode materials.

具有高容量和长循环寿命的低成本电极的开发是储能设备的重要问题。本文通过新颖的原位低温离子交换方法，从纳米晶ZnMn ₂ O ₄衍生出了独特的纳米结构四方LiMn ₂ O ₄（TLMO）电极，该电极在含Li离子的水性电解质中表现出混合的伪电容器和电池行为。。假电容和电池性能之间的互补作用使TLMO在高容量，长周期稳定性和可抑制的自放电方面综合表现出色，其对应物仅具有一种电化学行为，还有许多其他显着的假电容材料。使用操作/原位同步加速器X射线分析揭示了离子交换过程中的相变机理和电荷存储机理。这项研究可能会为电荷存储电极材料开辟一个新的设计概念。