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

ABSTRACT 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 BiSb ₃ alloy SIBs anode material, wherein BiSb ₃ NPs are embedded within nitrogen‐doped carbon multichannel nanofibers (BiSb ₃ NMCCNFs), exhibiting ultra‐long cycling stability. Specifically, the uniform dispersion of BiSb ₃ 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 BiSb ₃ NMCCNFs electrode exhibited pseudocapacitive‐dominant behavior, enabling exceptional rate capability (274.4 mAh g ⁻¹ at 10 A g ⁻¹ ). Critically, the BiSb ₃ 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)→Na ₃ (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.