A new type of core–shell nanocapsules with Ni nanoparticles as cores and amorphous CuO as shells have been synthesized through the arc-discharge method and subsequently annealing process. Amorphous CuO nanoshells lead to the improved stability and electrochemical performances. When evaluated as anode materials for lithium-ion batteries, the Ni/amorphous CuO nanocapsules deliver an initial discharge capacity of 1238.4 mAh g−1 at 100 mA g−1 and maintain a higher reversible capacity of 673.4 mAh g−1 over 100 cycles, compared to the Ni/crystalline CuO nanocapsules (392 mAh g−1). The feasibility of this material in lithium-ion batteries will offer guidelines for the future design of new materials with optimum properties and beneficial structural elements to realize improvements in electrochemical performances.