Cellulose-derived tin-oxide-nanoparticle-embedded carbon fibers as binder-free flexible Li-ion battery anodes

Cellulose has attracted attention as a biomass carbon precursor owing to its abundant reserves and unique properties such as a hierarchical fibrous structure and good mechanical properties. Here, we fabricate cellulose-derived carbon fibers via a facile electrospinning and carbonization process by using cellulose acetate precursor. The prepared carbon fibers are directly used as binder-free flexible anodes for Li ion batteries. They exhibit a high initial reversible specific capacity of 555 mA h g⁻¹ with better cycling stability than carbonized commercial cellulose electrodes. To design extensive lithium storage electrodes, cellulose-derived carbon fiber/SnO₂ composites are fabricated through electrospinning. In order to prevent the degradation of the active material, we encapsulate SnO₂ nanoparticles in cellulose-derived carbon fibers with a large amount of SnO₂ (46.4 wt%), which is evenly dispersed in the fibrous carbon matrix. Cellulose-derived carbon fiber/SnO₂ electrodes reveal a high reversible capacity of 667 mA h g⁻¹ and stable cycling retention of 76% over 100 cycles at 200 mA g⁻¹, which signify much better cycling performance than commercial SnO₂ nanoparticles. These properties are reflected in the advantages of cellulose-derived carbon fiber/SnO₂ composite electrodes such as high reactivity, good mechanical properties, and high electrical conductivity that originate from the cellulose-based fibril nanostructure.