A multi-layered microcapsule prepared through a microfluidic co-flow focusing approach as high-performance Li-ion battery anode

Engineering highly-stable and high-capacity energy-storage materials are significant for secondary batteries. Here, a multi-layered yolk-shell in yolk-shell microcapsule composing of yolk-shell Si@void@SnO2 nanospheres packaged inside a microcapsule is developed through a microfluidic co-flow focusing approach. The multi-layered microcapsules-based Li-ion battery anode displays 1005 mAh g-1 after 200 cycles and a 99.9% Coulombic efficiency; and the capacity remains 752 mAh g-1 after charging-discharging 900 times at-10 degrees C. In addition, a stable rate-performance is achieved, and the cycling performance keeps well at different charging/ discharging speeds. It is considered that the voids inside the microcapsules could accommodate the volumetric change of Si nanoparticles during cycling; and the porous morphology improves the transport of ions, which has been verified by a series of galvanostatic intermittent titration technique investigations. The high electro-chemical performance indicates a good potential for practical applications at real environments, and the engi-neering of microcapsule would be applicable for developing other energy-storage composites.