Enhanced Capacity and Cyclability of Si@NiSi₂ Nanocomposite Anodes Fabricated by Facile Electroless Ni Plating

Abstract

Although silicon (Si) has been proposed as the most promising anode material in lithium-ion batteries due to their high capacity (∼4000 mA h g −1 ), the poor cyclability resulting from the strain-induced pulverization caused by the severe volume change during charge/discharge hinders the industrial applications. Here, Si nanoparticles were conformally coated with either Ni, NiO, or NiSi 2 to suppress the tremendous volume change of Si, hence leading to prolonging the cycle life of the Si anode to a different degree. Both Si@Ni and Si@NiO nanocomposites were synthesized by one-step self-reducing (SR) electroless nickel plating without/with heat treatment, respectively, whereas Si@NiSi 2 nanocomposites were obtained by a two-step (SR + electroless nickel deposition, EN) process, followed by heat treatment. Among all these three nanocomposite anodes, Si@NiSi 2 prepared by 5 min of SR, 30 min of EN, and 400 °C annealing in sequence achieved the highest capacity of ∼1390 mA h g −1 and the best capacity retention of ∼86.6% with a Coulombic efficiency of 99% over 70 cycles. For comparison, the capacity retention of the Si@Ni and Si@NiO electrode over 70 cycles is estimated to be ∼67 and 75%, respectively. These results suggest that NiSi 2 could be a promising protective coating layer to effectively buffer the volume change of Si and promote the battery life.