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Manipulating Adsorption–Insertion Mechanisms in Nanostructured Carbon Materials for High‐Efficiency Sodium Ion Storage
Author(s) -
Qiu Shen,
Xiao Lifen,
Sushko Maria L.,
Han Kee Sung,
Shao Yuyan,
Yan Mengyu,
Liang Xinmiao,
Mai Liqiang,
Feng Jiwen,
Cao Yuliang,
Ai Xinping,
Yang Hanxi,
Liu Jun
Publication year - 2017
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201700403
Subject(s) - faraday efficiency , intercalation (chemistry) , materials science , anode , carbon fibers , adsorption , ion , graphite , chemical engineering , nanotechnology , electrochemistry , inorganic chemistry , electrode , composite material , organic chemistry , chemistry , composite number , engineering
Hard carbon is one of the most promising anode materials for sodium‐ion batteries, but the low Coulombic efficiency is still a key barrier. In this paper, a series of nanostructured hard carbon materials with controlled architectures is synthesized. Using a combination of in situ X‐ray diffraction mapping, ex situ nuclear magnetic resonance (NMR), electron paramagnetic resonance, electrochemical techniques, and simulations, an “adsorption–intercalation” mechanism is established for Na ion storage. During the initial stages of Na insertion, Na ions adsorb on the defect sites of hard carbon with a wide adsorption energy distribution, producing a sloping voltage profile. In the second stage, Na ions intercalate into graphitic layers with suitable spacing to form NaC x compounds similar to the Li ion intercalation process in graphite, producing a flat low voltage plateau. The cation intercalation with a flat voltage plateau should be enhanced and the sloping region should be avoided. Guided by this knowledge, nonporous hard carbon material has been developed which has achieved high reversible capacity and Coulombic efficiency to fulfill practical application.