A good anode material for Li-ion batteries(LIBs) needs fast Li⁺ ion transfer rate and small volume expansion ratio(VER). The density functional calculations are carried to explore the performance of the two-dimensional bilayer β-bismuthene(β-Bi) as the LIB anode material. The phonon spectra without virtual frequency, intact structure at 300 K after dynamic operation can prove the thermodynamical stability of the bilayer β-Bi. The band gap of the bilayer β-Bi is only 0.06 eV, which indicates that the bilayer β-Bi changes from a semiconductor to a metal, thus, it should have good electrical conductivity. The diffusion energy barrier of 0.08 eV is rather small compared to most reported anode materials, and can enable the battery to achieve a very fast charge/discharge rate, which is critical to the cycle life of LIB. The average open circuit voltage (OCV) is only 0.28 V and can realize the higher cycle efficiency of bilayer β-Bi anode. Surprisingly, the maximum 7% VER is much smaller than that of other anodes and enables it to avoid the rapid capacity decline during the charge/discharge cycle. Our results will support conclusive evidence to prove that the bilayer β-Bi should be the promising LIB anode.

锂离子电池 (LIBs) 的良好负极材料需要快速的 Li ⁺离子转移率和小体积膨胀比（VER）。进行密度泛函计算以探索二维双层β-铋烯（β-Bi）作为LIB负极材料的性能。动态运行后300 K下无虚频、结构完整的声子光谱可以证明双层β-Bi的热力学稳定性。双层β-Bi的带隙仅为0.06eV，表明双层β-Bi由半导体转变为金属，因此应具有良好的导电性。与大多数报道的负极材料相比，0.08 eV 的扩散能垒相当小，并且可以使电池实现非常快的充电/放电速率，这对 LIB 的循环寿命至关重要。平均开路电压（OCV)仅为0.28 V，可实现双层β-Bi负极更高的循环效率。令人惊讶的是，最大 7% 的 VER 远小于其他阳极，使其能够避免充电/放电循环期间容量的快速下降。我们的结果将支持确凿的证据，证明双层 β-Bi 应该是有前途的 LIB 阳极。