Biomass‐Derived Stress‐Regulating Additives for Microsilicon Anodes in Lithium‐Ion Batteries

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Microsilicon (μSi) anode, with an ultrahigh capacity of 3579 mAh g−1, presents less interfacial side reactions and lower production costs compared to nanosilicon, making it a promising candidate for lithium‐ion batteries. However, the severe local stress produced upon repeated lithium insertion and extraction causes structural deterioration, significantly reducing the cycling stability of μSi anodes. Here, biomass‐derived carbon microtubes are introduced into μSi electrodes as elasticity mediators to alleviate the stress generated during electrode cycling. After carbonization at a moderate temperature of 370 °C, the carbon tube walls retain some organic ingredients and exhibit impressive elasticity and resilience, which can effectively alleviate the volume expansion of μSi particles and prevent pulverization of the electrode. In addition, the large inner diameter of the carbon tube provides additional space to compensate for the volume expansion of microsized silicon. The μSi anode with carbon microtubes additives delivers an enhanced capacity of 1047 mAh g−1 after 200 cycles at a high current density of 2 A g−1. These results indicate that carbon microtubes are efficient stress‐regulating additives for μSi anodes, and further research may extend their application to other high‐capacity alloy anodes, such as SiOx, phosphorus‐based, and tin‐based anodes.