The formation of yolk–shell structured NiO nanospheres with enhanced lithium storage capacity

Abstract

NiO has been widely applied as an anode material for lithium-ion batteries (LIBs), but the weak conductivity of NiO and serious volume expansion usually lead to poor cycling performance. Herein, we report the synthesis of well-crystallized yolk–shell structured NiO nanospheres (NiO-30) through the direct pyrolysis of Ni coordination polymers (Ni-CPs). Compared to commercial NiO used for LIB anode materials with a capacity of 369 mA h g⁻¹, the resultant yolk–shell structured NiO nanospheres (NiO-30) demonstrate twice the capacity of 733 mA h g⁻¹ at the current density of 100 mA g⁻¹. Furthermore, the cycling stability and rate capability of the NiO-30 samples are much better than those of the commercial NiO. The yolk–shell structures can improve the electronic conductivity, benefit the Li⁺ ion transport path and buffer the volume changes during the lithium-insertion–extraction processes, which results in high discharge capacity, and good cycling performance and rate capability.