Microstructure modulation improving the stability performance of a Bi anode for lithium-ion batteries

Metallic Bi is a classic metal-type anode material characterized by its high volume-specific capacity (3785 mA h cm^-3) and theoretical specific capacity (386 mA h g^-1). However, during the charge and discharge processes of the battery, Bi undergoes significant volume expansion and contraction, which leads to a notable decline in battery performance. In this work, to suppress the volume expansion of bismuth and enhance battery performance and stability, a Bi-metal-organic-framework (Bi-MOF) is utilized as a precursor and combined with an organic polymerization coating process, followed by calcination, to obtain a double-carbon-coated lamellar structure (Bi/C@C_Ppy). The coated carbon layers inhibit the agglomeration of Bi particles and mitigate volume changes during charge-discharge cycles. After 100 cycles at 0.1 A g^-1, Bi/C@C_Ppy maintains a specific capacity of 526.4 mA h g^-1. Even after 900 extended cycles, it retains a specific capacity of 255.6 mA h g^-1 at 0.5 A g^-1. In situ XRD is employed to analyze the Li⁺ storage mechanism. Furthermore, a full cell with Li_1.2Ni_0.13Co_0.13Mn_0.64O₂ as the cathode and a Bi/C@C_Ppy-based anode achieves a capacity of 104.3 mA h g^-1 after 100 cycles at a current density of 0.05 A g^-1. This approach provides valuable insights into the precise structural design and preparation of high-performance rechargeable battery alloy negative electrode materials.