Vanadium disulfide flakes with nanolayered titanium disulfide coating as cathode materials in lithium-ion batteries
Vanadium disulfide flakes with nanolayered titanium disulfide coating as cathode materials in lithium-ion batteries
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DOI：
10.1038/s41467-019-09400-w
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发表时间：
2019-04-16
影响因子：
16.6
通讯作者：
Koratkar, Nikhil
中科院分区：
文献类型：
--
作者：
Li, Lu;Li, Zhaodong;Koratkar, Nikhil
与绝大多数半导体过渡金属二硫属化物不同，二硫化钒是金属性且导电的。这使得它作为锂离子电池的电极材料特别有前途。然而，由于循环过程中较大的 Peierls 畸变，二硫化钒表现出较差的稳定性。在这里，我们报告说，通过在二硫化钒薄片上保形涂覆类似于 2.5 nm 厚的二硫化钛层，可以使二硫化钒薄片在锂离子电池的电化学环境中保持稳定。密度泛函理论计算表明，二硫化钛涂层在锂化-脱锂过程中不易受到 Peierls 变形的影响，使其能够稳定下面的二硫化钒材料。二硫化钛涂覆的二硫化钒正极具有接近2 V的工作电压、高比容量（在200 mA g(-1)电流密度下接近180 mAh g(-1)）和倍率性能（在1000 mA g(-1)电流密度下接近70 mAh g(-1)），同时在400次充放电后容量保持率接近100%。
Unlike the vast majority of transition metal dichalcogenides which are semiconductors, vanadium disulfide is metallic and conductive. This makes it particularly promising as an electrode material in lithium-ion batteries. However, vanadium disulfide exhibits poor stability due to large Peierls distortion during cycling. Here we report that vanadium disulfide flakes can be rendered stable in the electrochemical environment of a lithium-ion battery by conformally coating them with a similar to 2.5 nm thick titanium disulfide layer. Density functional theory calculations indicate that the titanium disulfide coating is far less susceptible to Peierls distortion during the lithiation-delithiation process, enabling it to stabilize the underlying vanadium disulfide material. The titanium disulfide coated vanadium disulfide cathode exhibits an operating voltage of similar to 2 V, high specific capacity (similar to 180 mAh g(-1) @ 200 mA g(-1) current density) and rate capability (similar to 70 mAh g(-1) @ 1000 mA g(-1)), while achieving capacity retention close to 100% after 400 charge-discharge steps.