Graphite, a predominantly chosen anode material for commercial lithium ion batteries (LIBs), has been reported to have negligible intercalation capacity as an anode for sodium ion batteries (NIBs). Disordered carbon exhibits high Na intercalation capacity and emerges as a leading candidate for NIB applications.However, the mechanism of Na + ion insertion into disordered carbon is still controversial. Here, wepropose an ab initio model for disordered carbon and investigate the intercalation mechanism of Na into the layered domains. Our ab initio calculations reveal that a larger interlayer distance and the presence of defects can effectively overcome the van der Waals interaction between graphene sheets and help Na intercalation to form NaC 8 . The calculation results clarify the mechanism of the Na intercalation and account for the presence of sloping and flat regions of charge-discharge curves in disordered carbon reported in numerous experiments. This reveals new prospects for helping Na intercalation into graphite.

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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