High-rate performance boron-doped silicon flakes anode using a molten salts method for lithium-ion batteries

Abstract

Rate performance is also a key parameter for silicon to replace graphite serving as anode materials for lithium-ion batteries (LIBs), except for its high theoretical specific capacity. Herein, we fabricated the B-doped Si flakes with high-rate performance from low-cost industrial Si-Ca alloy and B2O3 via a facile molten-salt chemical exfoliation. The layered structure shortens diffusion ways of lithium ions . Moreover, B atoms in Si contribute to the increasement of the conductivity and the expansion of lattices. Benefiting from the doped and layered structure, the B-doped Si flakes electrode exhibits a specific capacity of ~800 mAh g−1 at 2 A g−1 with an initial coulombic efficiency of 81.5% and maintains 85% after 200 cycles. The reversible capacities of ~1250, ~1000 and ~842 mAh g−1 can be delivered at 0.4, 1, and 2 A g−1, respectively. The rational design of a special doped layered structure may propose a strategy for other materials.