Precise Construction of Sn/C Composite Membrane with Graphene-Like Sn-in-Carbon Structural Units toward Hyperstable Anode for Lithium Storage.

A new-type binder-free Sn/C composite membrane with densely stacked Sn-in-carbon nanosheets was prepared by vacuum-induced self-assembly of graphene-like Sn alkoxide and following in situ thermal conversion. The successful implementation of this rational strategy is based on the controllable synthesis of graphene-like Sn alkoxide by using Na-citrate with the critical inhibitory effect on polycondensation of Sn alkoxide along the and directions. Density functional theory calculations reveal that graphene-like Sn alkoxide can be formed under the joint action of oriented densification along the axis and continuous growth along the and directions. The Sn/C composite membrane constructed by graphene-like Sn-in-carbon nanosheets can effectively buffer volume fluctuation of inlaid Sn during cycling and much enhance the kinetics of Li diffusion and charge transfer with the developed ion/electron transmission paths. After temperature-controlled structure optimization, Sn/C composite membrane displays extraordinary Li storage behaviors, including reversible half-cell capacities up to 972.5 mAh g at a density of 1 A g for 200 cycles, 885.5/729.3 mAh g over 1000 cycles at large current densities of 2/4 A g, and terrific practicability with reliable full-cell capacities of 789.9/582.9 mAh g up to 200 cycles under 1/4 A g. It is worthy of noting that this strategy may open up new opportunities to fabricate advanced membrane materials and construct hyperstable self-supporting anodes in lithium ion batteries.