摘要
Sodium-ion batteries(SIBs)are considered the most up-and-coming complements for large-scale energy storage devices due to the abundance and cheap sodium.However,due to the bigger radius,it is still a great challenge to develop anode materials with suitable space for the intercalation of sodium ions.Herein,we present hard carbon microtubes(HCTs)with tunable apertures derived from low-cost natural kapok fibers via a carbonization process for SIBs.The resulted HCTs feature with smaller surface area and shorter Na+diffusion path benefitting from their unique micro-nano structure.Most importantly,the wall thickness of HCTs could be regulated and controlled by the carbonization temperature.At a high temperature of 1,600℃,the carbonized HCTs possess the smallest wall thickness,which reduces the diffusion barrier of Na+and enhances the reversibility Na+storage.As a result,the 1600HCTs deliver a high initial Coulombic efficiency of 90%,good cycling stability(89.4%of capacity retention over 100 cycles at 100 mA·g^(−1)),and excellent rate capacity.This work not only charts a new path for preparing hard carbon materials with adequate ion channels and novel tubular micro-nano structures but also unravels the mechanism of hard carbon materials for sodium storage.
基金
supported by the Natural Science Research Project for Universities in Anhui Province(No.KJ2021ZD0006)
the Natural Science Foundation of Anhui Province(No.2208085MB21)
the Fundamental Research Funds for the Central Universities of China(No.PA2022GDSK0056)
the University Synergy Innovation Program of Anhui Province(Nos.GXXT-2020-073 and GXXT-2020-074),the National Key R&D Program of China(No.2020YFA0406103)
the National Natural Science Foundation of China(Nos.21725102,91961106,91963108,and 22175165)
Singapore National Research Foundation under NRF RF Award No.Tier 12017-T1-001-075.
