Hollow biochar fiber enhanced conductive network with self-adaptive stress dispersion for highly robust silicon-based anodes

The high localized stress generated during (de)lithiation in silicon (Si)-based anodes causes electrode fracture and capacity degradation. Drawing inspiration from the theory of fiber-reinforced materials, we introduce carbonized kapok fiber (CKF) as a conductive additive for Si-based anodes, which effectively dissipates the internal stress induced by volumetric expansion within the electrode. Furthermore, the CKF additive offers long-range conductive pathways, enhancing the contact area compared to the point-to-point connections of the commercial conductive additive Super P, thereby facilitating the formation of efficient conductive networks within the electrode. Additionally, the unique hollow structure of CKF enhanced Li + transport within the electrode. The incorporation of 3 wt% CKF significantly improves the cycling stability of Si-based anodes, with SiOx anodes exhibiting an impressive capacity retention of 95.9 % after 300 cycles and SiC anodes retaining 90.0 % after 150 cycles at 0.5C. CKF is an excellent conductive additive for Si-based anodes in lithium-ion batteries with a very high potential for application.