为了满足储能市场对高功率电池的需求,开发具有高功率性能的锂离子电池负极材料成为必然发展趋势。本文通过湿式合成法将软碳和硬碳的前驱体进行复合,开发了一种新型的复合碳锂离子电池负极材料。考察了其克比容量、库仑效率、倍率性能...为了满足储能市场对高功率电池的需求,开发具有高功率性能的锂离子电池负极材料成为必然发展趋势。本文通过湿式合成法将软碳和硬碳的前驱体进行复合,开发了一种新型的复合碳锂离子电池负极材料。考察了其克比容量、库仑效率、倍率性能以及循环稳定性。用X射线粉末衍射(XRD)、拉曼、扫描电镜(SEM)以及透射电子显微镜(TEM)对所制备的复合碳材料的结构和表面形貌进行表征。结果表明,该复合碳材料同时具有软碳和硬碳的优点,且性能优于机械混合碳,在保持高比容量和高效率的前提下,倍率性能尤为突出,其2C容量可达154 m A·h/g,且2C/0.2C的容量保持率为64.2%;同时0.2C克比容量为240 m A·h/g,库仑效率为82%。经过5C充放电后,恢复0.2C小电流充放电后,容量保持率达99.8%,循环稳定性很好。XRD、拉曼以及透射电子显微镜的表征结果均表明软、硬碳在复合过程中不只是简单机械共混而是具有协同效应。展开更多
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 t...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.展开更多
文摘为了满足储能市场对高功率电池的需求,开发具有高功率性能的锂离子电池负极材料成为必然发展趋势。本文通过湿式合成法将软碳和硬碳的前驱体进行复合,开发了一种新型的复合碳锂离子电池负极材料。考察了其克比容量、库仑效率、倍率性能以及循环稳定性。用X射线粉末衍射(XRD)、拉曼、扫描电镜(SEM)以及透射电子显微镜(TEM)对所制备的复合碳材料的结构和表面形貌进行表征。结果表明,该复合碳材料同时具有软碳和硬碳的优点,且性能优于机械混合碳,在保持高比容量和高效率的前提下,倍率性能尤为突出,其2C容量可达154 m A·h/g,且2C/0.2C的容量保持率为64.2%;同时0.2C克比容量为240 m A·h/g,库仑效率为82%。经过5C充放电后,恢复0.2C小电流充放电后,容量保持率达99.8%,循环稳定性很好。XRD、拉曼以及透射电子显微镜的表征结果均表明软、硬碳在复合过程中不只是简单机械共混而是具有协同效应。
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)+3 种基金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.
文摘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.
