Hu Junping, Ouyang Chuying, Yang Shengyuan A, Yang Hui Ying
Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore.
Nanoscale Horiz. 2019 Mar 1;4(2):457-463. doi: 10.1039/c8nh00333e. Epub 2018 Dec 10.
Finding electrode materials with high capacity is a key challenge for developing lithium-ion batteries (LIBs). Graphene was once expected to be a promising candidate, but it turns out to be too inert to interact with Li. Here, by using first-principles calculations, we predict that germanium doped graphene, termed as Germagraphene, which has been achieved in a recent experiment, is a promising LIB anode material. We find that at the optimal Ge concentration, which corresponds to the chemical formula CGe, the specific capacity for Germagraphene can be as high as 1734 mA h g, over four times larger than that of graphite. We show that the material has good electrical conduction before and after Li adsorption. We also investigate the diffusion process of Li on Germagraphene, and find that the diffusion barrier is low (∼0.151 eV), implying fast Li diffusion. The calculated average intercalation potential is very low (∼0.03 V), which is beneficial for increasing the working voltage for full-cells. In addition, during the process of Li intercalation, the lattice change for the material is quite small (∼0.48%), implying a good cycling performance. These results suggest that Germagraphene could be a promising high-capacity anode material for LIBs.
寻找具有高容量的电极材料是开发锂离子电池（LIBs）的关键挑战。石墨烯曾被认为是一种有潜力的候选材料，但事实证明它过于惰性，无法与锂发生相互作用。在此，通过第一性原理计算，我们预测在最近的实验中已制备出的锗掺杂石墨烯（称为Germagraphene）是一种有潜力的LIB阳极材料。我们发现，在对应化学式CGe的最佳锗浓度下，Germagraphene的比容量可高达1734 mA h g，比石墨的比容量大四倍多。我们表明，该材料在锂吸附前后具有良好的导电性。我们还研究了锂在Germagraphene上的扩散过程，发现扩散势垒较低（约0.151 eV），这意味着锂的扩散速度很快。计算得到的平均嵌入电位非常低（约0.03 V），这有利于提高全电池的工作电压。此外，在锂嵌入过程中，该材料的晶格变化非常小（约0.48%），这意味着其具有良好的循环性能。这些结果表明，Germagraphene可能是一种有潜力的LIB高容量阳极材料。
