Borophene as an extremely high capacity electrode material for Li-ion   and Na-ion batteries
  Two-dimensional (2D) materials as electrodes is believed to be the trend for future Li-ion and Na-ion batteries technologies. Here, by using first-principles methods, we predict that the recently reported borophene (2D born sheet) can serve as an ideal electrode material with high electrochemical performance for both Li-ion and Na-ion batteries. The calculations are performed on the two experimentally stable borophene structures, namely \b{eta}12 and \c{hi}3 structures. The optimized Li and Na adsorption sites are identified, and the host materials are found to maintain good electric conductivity before and after adsorption. Besides advantages including small diffusion barriers and low average open-circuit voltages, most remarkably, the storage capacity can be as high as 1984 mA h g-1 in \b{eta}12 borophene and 1240 mA h g-1 in \c{hi}3 borophene for both Li and Na, which is several times higher than the commercial graphite electrode and is the highest among all the 2D materials discovered to date. Our results highly support that borophenes can be appealing anode materials for both Li-ion and Na-ion batteries with extremely high power density. 
Xiaoming Zhang, Junping Hu, Yingchun Cheng, Hui Ying Yang, Yugui Yao,   Shengyuan A. Yang
cond-mat.mes-hall