Ultra‐high‐rate Bi anode encapsulated in 3D lignin‐derived carbon framework for sodium‐ion hybrid capacitors
Zehua Lin, Xueqing Qiu, Xihong Zu, Xiaoshan Zhang, Lei Zhong, Shirong Sun, Shuhua Hao, Yingjuan Sun, Wenli Zhang
Abstract
Abstract Bismuth (Bi), as an alloy‐based anode material, has attracted much attention in the development of sodium‐ion hybrid capacitors (SIHCs) due to its high theoretical capacity. However, the volume expansion of the Bi‐based anode during the sodiation/desodiation process results in limited rate capability. In the present work, a porous Bi‐based composite was constructed by a one‐step hydrothermal method, and Bi was encapsulated in lignin‐derived nitrogen‐doped porous carbon (Bi@LNPC) after carbonization. The obtained Bi nanoparticles could effectively adapt to the strain and shorten the diffusion distance of Na + . In addition, porous carbon skeleton provides a rigid conductive network for electronic transportation. Therefore, the assembled sodium‐ion half‐cell with Bi@LNPC anode shows ultra‐high‐rate capability. When the current density was enhanced from 0.1 to 50 A·g −1 , the specific capacity decreased slightly from 351.5 to 342.8 mAh·g −1 . Even at an extremely high current density of 200 A·g −1 , it retains 81.3% capacity retention when compared to a current density of 1 A·g −1 . The SIHCs assembled by Bi@LNPC show a high energy density of 63 Wh·kg −1 . This work provides an effective method for developing high‐rate Bi anode materials for sodium‐ion hybrid capacitors (SIHCs) and sodium‐ion batteries (SIBs).