Sheng Binbin, Wang Lifeng, Huang Huijuan, Yang Hai, Xu Rui, Wu Xiaojun, Yu Yan
Hefei National Laboratory for Physical Sciences at the Microscale, Department of Materials Science and Engineering, CAS Key Laboratory of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui, 230026, China.
Dalian National Laboratory for Clean Energy (DNL), Chinese Academy of Sciences (CAS), Dalian, Liaoning Province, 116023, China.
Small. 2020 Dec;16(49):e2005272. doi: 10.1002/smll.202005272. Epub 2020 Nov 17.
The potassium ion batteries (KIBs) based on conversion/alloying reaction mechanisms show high theoretical capacity. However, their applications are hampered by the poor cyclability resulting from the inherent large volume variations and the sluggish kinetics during K repeated insertion/extraction process. Herein, taken Sb Se as a model material, by rational design, nickel doped-carbon coated Sb Se nanorods (denoted as (Sb Ni ) Se @C) are prepared through combined strategies of the conductive encapsulation and crystal structure modification. The carbon coating acts as an efficient buffer layer that maintains superior structural stability upon cycling. The introduction of Ni atoms can enhance electrical conductivity, leading to outstanding rate performance, which are confirmed by density functional theory calculation. The (Sb Ni ) Se @C displays excellent reversible capacity (410 mAh g at 0.1 A g after 100 cycles) and unprecedented rate capability (140 mAh g at 10 A g ). Furthermore, KFeHCF//(Sb Ni ) Se @C full cell exhibits a high specific capacity (408 mAh g at 0.1 A g ), superior rate capability (260 mAh g at 2 A g ). This work can open up a new avenue for the design of stable conversion/alloying-based anodes for high energy density KIBs.
基于转化/合金化反应机制的钾离子电池（KIBs）具有较高的理论容量。然而，由于在钾反复嵌入/脱出过程中固有的大体积变化和缓慢的动力学，其循环性能较差，阻碍了它们的应用。在此，以Sb₂Se₃为模型材料，通过合理设计，采用导电包覆和晶体结构改性相结合的策略制备了镍掺杂碳包覆的Sb₂Se₃纳米棒（表示为（Sb₂Ni）Se₃@C）。碳包覆作为一种有效的缓冲层，在循环过程中保持了优异的结构稳定性。镍原子的引入可以提高电导率，从而带来出色的倍率性能，这通过密度泛函理论计算得到了证实。（Sb₂Ni）Se₃@C表现出优异的可逆容量（100次循环后在0.1 A g⁻¹下为410 mAh g⁻¹）和前所未有的倍率能力（在10 A g⁻¹下为140 mAh g⁻¹）。此外，KFeHCF//（Sb₂Ni）Se₃@C全电池表现出高比容量（在0.1 A g⁻¹下为408 mAh g⁻¹）、优异的倍率能力（在2 A g⁻¹下为260 mAh g⁻¹）。这项工作可为设计用于高能量密度钾离子电池的稳定的基于转化/合金化的负极开辟一条新途径。
