Hou Zishan, Liu Yuanming, Yao Shuyun, Wang Shiyu, Ji Yingjie, Fu Weijie, Xie Jiangzhou, Yan Yi-Ming, Yang Zhiyu
State Key Laboratory of Organic-Inorganic Composites, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, People's Republic of China.
School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
Mater Horiz. 2024 Nov 11;11(22):5674-5683. doi: 10.1039/d4mh01006j.
In the quest for efficient supercapacitor materials, manganese-based layered oxide cathodes stand out for their cost-effectiveness and high theoretical capacity. However, their progress is hindered by the Jahn-Teller (J-T) distortion due to the unavoidable Mn to Mn reduction during ion storage processes. Our study addresses this challenge by stabilizing the KMnO cathode through strategic Mg substitution. This substitution leads to an altered Mn electronic configuration, effectively mitigating the strong J-T distortion during ion storage processes. We provide a comprehensive analysis combining experimental evidence and theoretical insights, highlighting the emergence of the weak and negative J-T effects with reduced structural deformation during electrochemical cycling. Our findings reveal that the KMnMgO cathode exhibits remarkable durability, retaining 96.0% of initial capacitance after 8000 cycles. This improvement is attributed to the specific electronic configurations of Mn ions, which play a crucial role in minimizing volumetric changes and counteracting structural deformation typically induced by the strong J-T distortion. Our study not only advances the understanding of managing J-T distortion in manganese-based cathodes but also opens new avenues for designing high-stability supercapacitors and other energy storage devices by tailoring electrode materials based on their electronic configurations.
在寻找高效超级电容器材料的过程中，锰基层状氧化物阴极因其成本效益高和理论容量大而脱颖而出。然而，由于在离子存储过程中不可避免地会发生锰到锰的还原，其发展受到 Jahn-Teller（J-T）畸变的阻碍。我们的研究通过用镁进行策略性替代来稳定 KMnO 阴极，从而应对这一挑战。这种替代导致锰的电子构型发生改变，有效地减轻了离子存储过程中的强烈 J-T 畸变。我们结合实验证据和理论见解进行了全面分析，突出了在电化学循环过程中随着结构变形减少，弱的和负的 J-T 效应的出现。我们的研究结果表明，KMnMgO 阴极表现出显著的耐久性，在 8000 次循环后仍保留初始电容的 96.0%。这种改善归因于锰离子的特定电子构型，它在最小化体积变化和抵消通常由强烈 J-T 畸变引起的结构变形方面起着关键作用。我们的研究不仅推进了对锰基阴极中 J-T 畸变管理的理解，还通过根据电极材料的电子构型定制电极材料，为设计高稳定性超级电容器和其他储能装置开辟了新途径。
