Zhang Jingke, Ren Haitao, Wang Baoxu, Cao Zhiwei, Xiang Hengxue, Wang Shichao, Zhu Meifang
College of Materials Science and Engineering, Qingdao University, Qingdao 266071, China.
State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, China.
Int J Biol Macromol. 2025 Aug;319(Pt 3):145541. doi: 10.1016/j.ijbiomac.2025.145541. Epub 2025 Jun 25.
Hard carbon-based sodium-ion batteries (SIBs) anodes still face a significant challenge that the oxygen-containing functional groups and inherent defects result in an irreversible natrization during the initial charging process. The pre-sodiation strategy is designed to compensate for the consumption of sodium ions, typically achieved by adding sodium ion supplements. In this study, we propose an intrinsic pre-sodiation strategy based on hardwood kraft lignin (HKL), which is extracted using sodium hydroxide (NaOH) and sodium sulfide. Self-supported HKL ultrafine carbon fiber anodes with varying sodium contents (HKL-NaX-CFs) were prepared successfully through electrospinning, stabilization, and carbonization. The effects of NaOH on HKL under the dual influences of pre-sodiation and activation was investigated systematically, including the interaction between NaOH and HKL, the thermal properties of HKL, the morphology, microcrystalline structure and electrochemical properties of HKL-based ultrafine carbon fibers (HKL-CFs). Results indicate that pre-sodiation strategy increased the layer spacing of graphite lamella, pore volume, and diffusion-controlled capacity of HKL-CFs, leading to better capacity and rate performance. Notably, the HKL-Na2-CF anode exhibited a capacity of 231.7 mAh g at 30 mA g and 68.3 mAh g at 2000 mA g. The intrinsic pre-sodiation strategy offers an inspiration for the supplement of sodium ions.
