Hard carbon anodes derived from phenolic resin/sucrose cross-linking network for high-performance sodium-ion batteries

Hard carbons are widely studied as anode materials for sodium-ion batteries (SIBs) due to their high Na-storage capacity, long cycle life, and low cost. However, the low initial coulombic efficiency (ICE) and poor cycle performance remain bottleneck concerns that necessitate a comprehensive material engineering solution. Herein, we propose a facile strategy to synthesize amorphous carbons with pseudo-graphitic dominated crystalline, expanded interlayer spacing, and reduced surface defects via carbonization of the cross-linking network of phenolic resin and sucrose. An elaborate structural and electrochemical characteristics analysis has been investigated against different sucrose contents and carbonization temperatures. The representative PF-S-55-1200 with the optimum cross-linking degree as well as carbonization temperature realizes a high reversible Na-storage capacity of 323.0mAhg(-1) with an ICE as high as 86.4%, much superior to the pristine phenolic resin pyrolytic carbon with a capacity of 267.1mAhg(-1) and an ICE of 46.3%. The hybrid hard carbons also exhibit robust structural stability with a prolonged cycle lifespan evidenced by a retained capacity of 238.3mAhg(-1) at a current density of 200mAg(-1) over 1500 cycles. The proposed route promises low-cost and high-performance hybrid hard carbons with optimized structural configuration for advanced SIBs.