Controllable self-assembled mesoporous silicon nanocrystals framework as anode material for Li-ion battery

Abstract Constructing porous silicon is one of the effective ways to ease the volume change (~320%) of the silicon-based anode. Thus, the design and construction of the porous structure of silicon by the particle size of Mg, the reaction temperature, ramp rate, and time of magnesiothermic reduction (MR) have achieved increasing attention. Here, a controllable self-assembled mesoporous diatomite-derived silicon nanocrystals framework (MRHDE-Si) can be adjusted directly by employing sodium chloride (NaCl) as a “liquid” interface via a MR method. As the proportion of Mg powder and NaCl increases from 1:0 to 1:10, the pore morphology level of MRHDE-Si changes from open-pore morphology to closed pore and tends to be more regular and affects the electrochemical performance of the electrode. Among as-prepared electrodes, the MRHDE-Si-5 electrode exhibits the optimal cycle performance that shows the specific capacity remains as high as 1290.9 mAh g-1 after 50 cycles at a current density of 200 mA g–1. Due to its smallest particle size of 23 nm, a suitable pore structure, pore volume (0.69 cm−3 g−1), the most feasible pore size (12.64 nm), which can provide abundant ion channels and charge transfer channels, shorten the diffusion path of Li+, enhance charge transfer capability, and effectively adapt to the stress caused by the volume expansion of Si as a buffering region. This “liquid” interface self-assembled strategy provides a simple and easy-to-operate way to design and prepare controllable porous silicon composite materials for applications in the field of new energy.