change during the lithiation/delithiation process and to limit particle coalescence and 2) the confi nement of Sn (or SnO 2 ) particles in porous matrix in order to stabilize the particles, to limit particle coalescence and to improve the electronic conductivity. Positive effects of nanoconfi nement of metals in porous carbons have been already demonstrated for several applications such as hydrogen storage [ 10,11 ] and catalysis applications. [ 12,13 ] Very recently, this concept is being also extended to Li-alloying materials such Fe 2 O 3 , [ 14 ] sulfur [ 15 ] and phosphorous. [ 16 ] In the same manner, mesoporous carbons with high surface area, tunable pore size and porous volume were proven very promising in enhancing the behaviour of Sn anodes. [17][18][19][20] In this regard, Hassan et al. [ 17 ] reported the synthesis of Sn/SnO 2 embedded in mesoporous carbon for application as negative electrode in Li-ion batteries. The mesoporous carbon was obtained by hard-template procedure involving repetitive impregnation of ordered silica template (SBA-15) with sucrose and sulfuric acid, followed by carbonization in inert gas at high temperatures and selective elimination of silica template by strong acid treatement (HF). Sn was then introduced via liquid impregnation with SnCl 2 .2H 2 O aqueous solution and subsequently thermally treated in Ar/H 2 at different temperatures. The composite was reported to possess a reversible initial capacity of 799 mAh g −1 and a retained capacity after 50 cycles of 670 mAh g −1 at current density of 100 mA g −1 and in the potential window (0.01-3 V). However, despite the perfect hexagonal confi guration of the issued carbon, its preparation method presents major drawbacks particularly related to the long preparation procedure, the use of dangerous reagents, and its high cost which makes the upscaling of this material's production diffi cult. Wang et al. [ 18 ] also reported a similar procedure with the difference that the Sn precursor was introduced into the template at the same time as the carbon precursors. After carbonization and template removal, the resulting composite material contained Sn particles rather embedded in the walls of the carbon nanochannels, and not in the carbon pores. The cycling performances of the composite were reported up to 100 th cycle, showing a capacity close to 560 mAh g −1 at a 0.1C rate and close to 360 mAh g −1 at C rate. The effect of the mesoporosity on the cycling performances of the composite could not be clearly elucidated and the composite was not well adapted to higher current rates.Contrarily to the previous examples, Xu et al. prepared a Sn/C mesoporous composite anode material using the softtemplate method. [ 20 ] In this approach, a structure directing agent, such as a triblock compolymer (Pluronic F127) allows the self-assembly of carbon precursors (resolcinol-formaldehye) into micelles and an ordered carbon (7-8 nm pore diameter) can be obtained after a carbonization step. This method avoids Major research and development efforts are...
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