As a new type of capacitor–battery hybrid energy storage device, metal‐ion capacitors have attracted widespread attention because of their high‐power density while ensuring energy density and long lifespan. Potassium‐ion capacitors (KICs) featuring the merits of abundant potassium resources, lower standard electrode potential, and low cost have been considered as potential alternatives to lithium‐/sodium‐ion capacitors. However, KICs still face issues including unsatisfactory reaction kinetics, low energy density, and poor lifetime owing to the large radius of the potassium ion. In this Review, the importance of emerging potassium‐ion capacitor is addressed. The Review offers a brief discussion of the fundamental working principle of KICs, along with an overview of recent advances and achievements of a variety of electrode materials for dual carbon and non‐dual carbon KICs. Furthermore, electrolyte chemistry, binders as well as electrode/electrolyte interface, are summarized. Finally, existing challenges and perspectives on further development of KICs are also presented.

中文翻译：

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新兴的钾离子混合电容器。

金属离子电容器作为一种新型的电容器-电池混合储能装置，由于其高功率密度同时又确保了能量密度和长寿命，因此受到了广泛的关注。钾离子电容器（KIC）具有丰富的钾资源，较低的标准电极电势和低成本的优点，已被认为是锂/钠离子电容器的潜在替代品。然而，由于钾离子的半径大，KIC仍然面临着包括动力学动力学欠佳，能量密度低和寿命差等问题。在这篇评论中，新兴的钾离子电容器的重要性得到了解决。该评论简要介绍了各主要投资机构的基本工作原理，概述了用于双碳和非双碳KIC的各种电极材料的最新进展和成就。此外，总结了电解质化学，粘合剂以及电极/电解质界面。最后，还介绍了进一步发展KIC的现有挑战和前景。