Department of Physics, University of Ulsan, Ulsan 44610, Republic of Korea.
Nanotechnology. 2017 Apr 28;28(17):175401. doi: 10.1088/1361-6528/aa6536. Epub 2017 Mar 30.
A comparative study of the monovalent (Li, Na, and K) and multivalent (Be, Mg, Ca, and Al) metal ion adsorption and diffusion on an electronically semi-metallic two-dimensional nanosheet of 1T structured TiS is presented here to contribute to the search for abundant, cheap, and nontoxic ingredients for efficient rechargeable metal ion batteries. The total formation energy of the metal ion adsorption and the Bader charge analysis show that the divalent Mg and Ca ions can have a charge storage density double that of the monovalent Li, Na, and K ions, while the Be and Al ions form metallic clusters even at a low adsorption density because of their high bulk energies. The adsorption of Mg ions shows the lowest averaged open circuit voltage (0.13 V). The activation energy barriers for the diffusion of metal ions on the surface of the monolayer successively decrease from Li to K and Be to Ca. Mg and Ca, being divalent, are capable of storing a higher power density than Li while K and Na have a higher rate capability than the Li ions. Therefore, rechargeable Li ion batteries can be totally or partially replaceable by Mg ion batteries, where high power density and high cell voltage are required, while the abundant, cheap, and fast Na ions can be used for green grid applications.
本文对单价（Li、Na 和 K）和多价（Be、Mg、Ca 和 Al）金属离子在具有 1T 结构的 TiS 二维纳米片上的吸附和扩散进行了比较研究，以期为寻找丰富、廉价和无毒的成分用于高效可充电金属离子电池做出贡献。金属离子吸附的总形成能和 Bader 电荷分析表明，二价 Mg 和 Ca 离子的电荷存储密度是单价 Li、Na 和 K 离子的两倍，而 Be 和 Al 离子由于其较高的体能，即使在低吸附密度下也会形成金属簇。Mg 离子的吸附表现出最低的平均开路电压（0.13V）。金属离子在单层表面扩散的活化能垒从 Li 到 K 和 Be 到 Ca 依次降低。Mg 和 Ca 作为二价离子，能够比 Li 存储更高的功率密度，而 K 和 Na 比 Li 离子具有更高的倍率性能。因此，在需要高功率密度和高电池电压的情况下，可充电锂离子电池可以完全或部分被镁离子电池取代，而丰富、廉价和快速的钠离子可用于绿色电网应用。
