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Highly Crystalline Lithium Titanium Oxide Sheets Coated with Nitrogen‐Doped Carbon enable High‐Rate Lithium‐Ion Batteries
Author(s) -
Han Cuiping,
He YanBing,
Li Baohua,
Li Hongfei,
Ma Jun,
Du Hongda,
Qin Xianying,
Yang QuanHong,
Kang Feiyu
Publication year - 2014
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201402305
Subject(s) - materials science , crystallinity , lithium (medication) , chemical vapor deposition , carbon fibers , chemical engineering , nitrogen , inorganic chemistry , nanotechnology , chemistry , composite material , organic chemistry , medicine , endocrinology , composite number , engineering
Sheets of Li 4 Ti 5 O 12 with high crystallinity are coated with nitrogen‐doped carbon (NC‐LTO) using a controlled process, comprising hydrothermal reaction followed by chemical vapor deposition (CVD). Acetonitrile (CH 3 CN) vapor is used as carbon and nitrogen source to obtain a thin coating layer of nitrogen‐doped carbon. The layer enables the NC‐LTO material to maintain its sheet structure during the high‐temperature CVD process and to achieve high crystallinity. Doping with nitrogen introduces defects into the carbon coating layer, and this increased degree of disorder allows fast transportation of lithium ions in the layer. An electrode of NC‐LTO synthesized at 700 °C exhibits greatly improved rate and cycling performance due to a markedly decreased total cell resistance and enhanced Li‐ion diffusion coefficient ( D Li ). Specific capacities of 159.2 and 145.8 mA h g −1 are obtained using the NC‐LTO sheets, at charge/discharge rates of 1 and 10 C, respectively. These values are much higher than values for LTO particles did not undergo the acetonitrile CVD treatment. A capacity retention value as high as 94.7 % is achieved for the NC‐LTO sheets after 400 cycles in a half‐cell at 5 C discharge rate.