阳极
离子
电化学
石墨烯
材料科学
同步加速器
碳纤维
插层(化学)
化学物理
钠
纳米尺度
工作(物理)
化学工程
钠离子电池
电极
纳米技术
化学
无机化学
物理化学
热力学
法拉第效率
有机化学
复合数
复合材料
工程类
物理
核物理学
冶金
作者
Aurora Gómez-Martín,J. Martı́nez-Fernández,Mirco Ruttert,Martin Winter,Tobias Placke,J. Ramírez‐Rico
标识
DOI:10.1021/acs.chemmater.9b01768
摘要
Hard carbons are the material of choice as negative electrode in sodium ion batteries. Despite being extensively studied, there is still debate regarding the mechanisms responsible for storage in low- and high-potential regions. This work presents a comprehensive approach to elucidate the involved storage mechanisms when Na ions insert into such disordered structures. Synchrotron X-ray total scattering experiments were performed to access quantitative information on atomic ordering in these materials at the nanoscale. Results prove that hard carbons undergo an atomic rearrangement as the graphene layers cross-link at intermediate temperatures (1200–1600 °C), resulting in an increase of the average interplanar distance up to 1400 °C, followed by a progressive decrease. This increase correlates with the positive trend in the reversible capacity of biomass-derived carbons when processed up to 1200–1600 °C due to an increased capacity at low potential (≤0.1 V vs Na/Na+). A decrease in achievable sloping capacity with increasing heat-treatment temperature arises from larger crystalline domains and a lower concentration of defects. The observed correlation between structural parameters and electrochemical properties clearly supports that the main storage of Na ions into a hard-carbon structure is based on an adsorption–intercalation mechanism.
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