High-Performance Cathode of Sodium-Ion Batteries Enabled by a Potassium-Containing Framework of K0.5Mn0.7Fe0.2Ti0.1O2
High-Performance Cathode of Sodium-Ion Batteries Enabled by a Potassium-Containing Framework of K0.5Mn0.7Fe0.2Ti0.1O2
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K0.5Mn0.7Fe0.2Ti0.1O2 含钾骨架实现的高性能钠离子电池正极
DOI：
10.1021/acsami.0c02157
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发表时间：
2020
影响因子：
9.5
通讯作者：
Wan Li-Jun
中科院分区：
文献类型：
--
作者：
Xu Yan-Song;Gao Jing-Chi;Tao Xian-Sen;Sun Yong-Gang;Liu Yuan;Cao An-Min;Wan Li-Jun
钠离子电池（SIB）具有丰富的钠资源，是大规模电能存储的有希望的候选者。然而，它们的发展面临着具有稳定框架的令人满意的阴极材料的可用性的挑战，以适应大尺寸Na+（1.02 Å）的运输，其连续插入/脱出很容易引起晶体材料不可逆的体积变形，导致不可避免的结构失效和容量衰减。在这里，与之前针对含Na+化合物的合成工作不同，我们揭示了通过采用K+基层状金属氧化物实现高度可逆的钠化/脱钠过程的可能性，其配方为K0.5Mn0.7Fe0.2Ti0.1O2(KMFT)，它是一种P2型结构，具有宽的层间距以容纳K+(1.38 Å)。我们证明，初始 K+/Na+ 交换可以将 Na+ 引入晶格，同时少量 K+ 保留在内部，这对于确保扩大通道以实现快速稳定的 Na+ 扩散发挥着重要作用。 KMFT 电极在 10 mA g-1 下具有 147.1 mA h g-1 的高初始放电容量，并具有出色的长循环稳定性，在 500 mA g-1 下循环 1000 次后容量保持率为 71.5%。这些结果为开发稳定的SIB阴极提供了新的设计策略，以促进其未来的应用。
Sodium-ion batteries (SIBs) are promising candidates for large-scale electric energy storage with abundant sodium resources. However, their development is challenged by the availability of satisfactory cathode materials with stable framework to accommodate the transportation of large-sized Na+(1.02 Å), whose continuous insertion/extraction can easily cause irreversible volumetric deformation in the crystalline material, leading to inevitable structural failure and capacity fading. Here, different from the previous synthesis efforts targeting at Na+containing compounds, we unveil the possibility of achieving a highly reversible sodiation/desodiation process by resorting to a K+-based layered metal oxide formulated as K0.5Mn0.7Fe0.2Ti0.1O2(KMFT), which is a P2 type in structure with a wide interlayer spacing to sit K+(1.38 Å). We demonstrate that an initial K+/Na+exchange can introduce Na+into the lattice while a small amount of K+remains inside, which plays a significant role in ensuring enlarged channels for a fast and stable Na+diffusion. The KMFT electrode delivers a high initial discharge capacity of 147.1 mA h g–1at 10 mA g–1and outstanding long cycling stability with capacity retention of 71.5% after 1000 cycles at 500 mA g–1. These results provide a new design strategy for the development of stable SIBs cathodes to facilitate their future applications.