Hyperaccumulation Route to Ca-Rich Hard Carbon Materials with Cation Self-Incorporation and Interlayer Spacing Optimization for High-Performance Sodium-Ion Batteries
Kaihua Yu, Huichun Zhao, Xinran Wang, Minghao Zhang, Ruiqi Dong, Ying Li, Ying Bai, Huajie Xu, Chuan Wu
Abstract
The hard carbon (HC) has been emerging as one of the most promising anode materials for sodium-ion batteries (SIBs). Incorporation of cations into the HC lattice proved to be effective to regulate their d-interlayer spacing with a modified SIB performance. However, the complexity and high cost of current synthetic processes limited its large-scale application in SIBs. Through the natural hyperaccumulation process, a cost-effective and scale-up-driven procedure to produce Ca-ion self-incorporated HC materials was proposed by applying tamarind fruits as the precursor with the enrichment of Ca ions. In virtue of one-step pyrolysis, the self-incorporated and well-distributed Ca ions in tamarind fruits had successfully served as the buffer layer to expand the d-interlayer spacing of HC materials. Furthermore, the natural porosity hierarchy could be largely preserved by the optimization of calcination temperature. As a result, the Ca-rich HC material had exhibited the optimized cycling performance (326.7 mA h g–1 at 50 mA g–1 and capacity retention rate of 89.40% after 250 cycles) with a high initial Coulombic efficiency of 70.39%. This work provided insight into applying the hyperaccumulation effect of biomass precursors to produce doped HC materials with ion self-incorporation and the optimized d-interlayer spacing, navigating its large-scale application for high-performance SIBs.