incorporation of conductive agents, [9][10][11] doping of metal ions, [12][13][14] and nanonization, that is, reduction in particle size. [15,16] Although all of these methods yielded notable results, our proposed alternative synthesis is greatly on-par, in addition to being a one-pot, facile, and inexpensive process which requires no additional precursors and processing-a very favorable route with manufacturing considerations.Chiang and co-workers summarized available electronic conductivity data for LTO, in which the defective-LTO (with oxygen vacancies) was of the highest reported electronic conductivity. [17] Therefore, it has gotten great interest and numerous researchers had engineered processes to generate oxygen vacancies in the LTO structure. [18][19][20] With amorphous carbon coating, Chen and co-workers demonstrated lower Li ion (Li + ) interfacial transfer resistance which dramatically enhanced the battery performance. [21] Altogether achieving a "double" effect, Wang et al. introduced nanosized LTO with surface modifications of Ti (III) and carbon with improved surface conductivity and restricted particle growth due to the carbonization of polyaniline (PANI); [22] however, they were not able to maximize the effects of oxygen vacancies by generating a low level; and their nonuniform carbon layers can possibly impede Li + transport, especially when graphitized. [23] Finally, the importance of these modifications in relation to the Li + interfacial charge-transfer resistance was not highlighted in the aforementioned studies.Herein, we propose a one-pot, facile, and extremely inexpensive strategy by using conventional solid-state precursors of lithium carbonate (Li 2 CO 3 ) and titanium oxide (TiO 2 ) in an ethanol solution, through which a high level of oxygen vacancies and conformal amorphous carbon coating were simultaneously achieved. The formation mechanism of the one-pot synthesized, highly oxygen-deficient, and amorphous-carbon-coated LTO, as well as the origin of its superior electrochemical properties, are elaborated with the aid of the ab initio calculation. The enhanced interfacial electrochemical properties as well as the stabilization of highly oxygen-deficient structure are attributed to the conformal amorphous carbon. The dramatic reduction of overall resistance was in the Li + interfacial charge transfer, which sheds light to an emerging importance of interfacial modification, is highlighted in this paper.The lithium titanate defect spinel, Li 4 Ti 5 O 12 (LTO), is a promising "zero-strain" anode material for lithium-ion batteries in cycling-demanding applications. However, the low-rate capability limits its range of applications. Surface modifications, for example, coating and defect engineering, play an intriguing role in interfacial electrochemical processes. Herein, a novel synthesis of highly oxygen-deficient "defective-LTO" anode material with highrate performance is reported. It is synthesized using conventional precursors via a one-pot thermal reduction process. A high level of ox...

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Raman spectroscopy was shown to be sensitive to the presence of diluted low-concentration defects in both pristine and carbon-coated lithium titanate.

Charge‐transfer kinetics between electrodes and electrolytes critically determines the performance of lithium‐ion batteries (LIBs). Lithium titanate defect spinel (Li4Ti5O12, LTO) is a safe and durable anode material, but its relatively low energy density limits the range of applications. Utilizing the low potential region of LTO is a straightforward strategy for increasing energy density. However, the electrochemical characteristics of LTO at low potentials and the properties of the solid‐electrolyte interphase (SEI) on LTO are not well understood. Here, we investigate the charge‐transfer kinetics of the SEI formed between model LTO thin‐film electrodes and organic electrolytes with distinct solvation ability using AC impedance spectroscopy whereas their stability was assessed by cyclic voltammetry of ferrocene. With the SEI film on LTO, the Li+ desolvation was rate‐determining step but with larger activation energies, which showed a strong dependence on the solvation ability of electrolyte. The activation energies of desolvation for the fluoroethylene carbonate+dimethyl carbonate‐ and ethylene carbonate+diethyl carbonate‐based systems increased from 35 and 55 to 44 and 67 kJ mol−1, respectively, and that for the propylene carbonate‐based system did not noticeably change at around 67 kJ mol−1. In addition, the SEI passivation of LTO was much slower than that of graphite, and the rate also strongly depended on the solvation ability of the electrolyte. Understanding the surface properties of LTO at low potentials opens the door for high‐energy‐density LTO‐based LIBs.