Liu Bingqiu, Zhang Qi, Ali Usman, Li Yiqian, Hao Yuehan, Zhang Lingyu, Su Zhongmin, Li Lu, Wang Chungang
Faculty of Chemistry, Northeast Normal University Changchun 130024 P. R. China
Chem Sci. 2022 Aug 27;13(36):10846-10855. doi: 10.1039/d2sc03824b. eCollection 2022 Sep 21.
Potassium manganese hexacyanoferrate (KMnHCF) suffers from poor cycling stability in potassium-ion batteries due to the Jahn-Teller effect, and experiences destabilizing asymmetric expansions and contractions during cycling. Herein, hollow nanospheres consisting of ultrasmall KMnHCF nanocube subunits (KMnHCF-S) are developed by a facile strategy. XRD analysis demonstrates that the traditional phase transition for KMnHCF is replaced by a single-phase solid-solution reaction for KMnHCF-S, which effectively suppresses the Jahn-Teller effect. From DFT calculations, it was found that the calculated reaction energy for K extraction in the solid-solution reaction is much lower than that in the phase transition, indicating easier K extraction during the solid-solution reaction. KMnHCF-S delivers high capacity, outstanding rate capability, and superior cycling performance. Impressively, the K-ion full cell composed of the KMnHCF-S cathode and graphite anode also displays excellent cycling stability. The solid-solution reaction not only suppresses the Jahn-Teller effect of KMnHCF-S but also provides a strategy to enhance the electrochemical performance of other electrodes which undergo phase transitions.
由于 Jahn-Teller 效应，六氰合铁酸钾锰（KMnHCF）在钾离子电池中循环稳定性较差，并且在循环过程中会经历不稳定的不对称膨胀和收缩。在此，通过一种简便的策略制备了由超小 KMnHCF 纳米立方体亚基组成的中空纳米球（KMnHCF-S）。XRD 分析表明，KMnHCF 的传统相变被 KMnHCF-S 的单相固溶体反应所取代，这有效地抑制了 Jahn-Teller 效应。从 DFT 计算可知，固溶体反应中钾提取的计算反应能量远低于相变中的反应能量，表明在固溶体反应中钾提取更容易。KMnHCF-S 具有高容量、出色的倍率性能和优异的循环性能。令人印象深刻的是，由 KMnHCF-S 阴极和石墨阳极组成的钾离子全电池也表现出优异的循环稳定性。固溶体反应不仅抑制了 KMnHCF-S 的 Jahn-Teller 效应，还提供了一种提高其他经历相变的电极电化学性能的策略。
