Zhou Limin, Jiao Peixin, Fang Liang, Liu Luojia, Hao Zhimeng, Wang Haihua, Kang Yong-Mook, Zhang Kai, Chen Jun
Department Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Engineering Research Center of High-efficiency Energy Storage (Ministry of Education), Renewable Energy Conversion and Storage Center (RECAST), College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China.
Department of Energy and Materials Engineering, Dongguk University-Seoul, Seoul 04620, Republic of Korea.
ACS Nano. 2021 Aug 24;15(8):13486-13494. doi: 10.1021/acsnano.1c04041. Epub 2021 Aug 2.
Metal phosphides as anode materials for alkali-metal ion batteries have captured considerable interest due to their high theoretical capacities and electronic conductivity. However, they suffer from huge volume expansion and element segregation during repetitive insertion/extraction of guest ions, leading to structure deterioration and rapid capacity decay. Herein, an amorphous SnGeP was constructed through a two-phase intermediate strategy based on the elemental composition modulation from two crystalline counterparts and applied in alkali-metal ion batteries. Differing from crystalline P-based compounds, the amorphous structure of SnGeP effectively reduces the volume variation from above 300% to 225% during cycling. The ordered distribution of cations and anions in the short-range ensures the uniform distribution of each element during cycles and thus contributes to durable cycling stability. Moreover, the long-range disordered structure of amorphous material shortens the ion transport distance, which facilitates diffusion kinetics. Benefiting from the aforementioned effects, the amorphous SnGeP delivers a high Na storage capacity of 1132 mAh g at 0.1 A g over 100 cycles. Even at high current densities of 2 and 10 A g, its capacities still reach 666 and 321 mAh g, respectively. As an anode for Li storage, the SnGeP similarly also exhibits better cycling stability and rate performance compared to its crystalline counterparts. Significantly, the two-phase transition strategy is generally applicable to achieving other amorphous metal phosphides such as GeP. This work would be helpful for constructing high-performance amorphous anode materials for alkali-metal ion batteries.
金属磷化物作为碱金属离子电池的负极材料，因其高理论容量和电子导电性而备受关注。然而，在客体离子的反复嵌入/脱出过程中，它们会经历巨大的体积膨胀和元素偏析，导致结构恶化和容量快速衰减。在此，通过基于两种晶体对应物的元素组成调制的两相中间策略构建了非晶态的SnGeP，并将其应用于碱金属离子电池。与结晶态的磷基化合物不同，SnGeP的非晶态结构有效地将循环过程中的体积变化从300%以上降低到225%。阳离子和阴离子在短程内的有序分布确保了各元素在循环过程中的均匀分布，从而有助于实现持久的循环稳定性。此外，非晶态材料的长程无序结构缩短了离子传输距离，有利于扩散动力学。受益于上述效应，非晶态SnGeP在0.1 A g下100次循环中提供了1132 mAh g的高钠存储容量。即使在2和10 A g的高电流密度下，其容量仍分别达到666和321 mAh g。作为锂存储的负极，SnGeP与其结晶对应物相比同样也表现出更好的循环稳定性和倍率性能。值得注意的是，两相转变策略通常适用于制备其他非晶态金属磷化物，如GeP。这项工作将有助于构建用于碱金属离子电池的高性能非晶态负极材料。
