BiSb Alloy in Multichannel Carbon Fibers for High‐Rate and Long‐Cycling Sodium‐Ion Battery

Although sodium-ion batteries (SIBs) hold significant potential for large-scale energy storage applications, their commercialization is hindered by limited cycle life and insufficient energy density. Herein, we report a BiSb₃ alloy SIBs anode material, wherein BiSb₃ NPs are embedded within nitrogen-doped carbon multichannel nanofibers (BiSb₃ NMCCNFs), exhibiting ultra-long cycling stability. Specifically, the uniform dispersion of BiSb₃ nanoparticles within the carbon matrix effectively suppresses volume expansion and particle agglomeration during the desodiation/sodiation processes, thereby achieving high-capacity retention (313.3 mAh g^-1 after 800 cycles at 1 A g^-1). Moreover, the BiSb₃ NMCCNFs electrode exhibited pseudocapacitive-dominant behavior, enabling exceptional rate capability (274.4 mAh g^-1 at 10 A g^-1). Critically, the BiSb₃ NMCCNFs //NVP full cell maintains a reversible capacity of 172.9 mAh g^-1 after 1000 cycles at 1 A g^-1, alongside outstanding rate performance. The sodium storage mechanism was identified as a two-step reversible alloying reaction of "BiSb→ Na(BiSb)→Na₃(BiSb)" through in situ XRD and ex situ TEM characterization, further verifying the stability of the material structure. This work presents a facile structural design strategy for high-performance alloy anodes, addressing key challenges in the application pathway of SIBs.