Phase Boundary Derived Pseudocapacitance Enhanced Nickel‐Based Composites for Electrochemical Energy Storage Devices

Several strategies have been employed to improve the performance of energy storage devices through the development of new electrode materials. The construction of transition metal compound composite electrodes plays an important role in promoting the performance of energy storage devices. However, understandings of and insight into how to enhance the composites properties are rarely reported. Taking nickel‐based compounds as an example, Ni₃N@Ni₃S₂ hybrid nanosheets are reported as a high‐performance anode material for lithium‐ion batteries that delivers higher lithium storage properties than the pristine Ni₃N and Ni₃S₂ electrodes. This demonstrates that the phase boundaries between the Ni₃N and Ni₃S₂ may contribute additional lithium storage, which leads to a synergistic effect via the high pseudocapacitance contribution from the outstanding conductivity of Ni₃N and enhanced diffusion‐controlled capacity of Ni₃S₂. The use of composites prepared through sulfuration of hydrothermally annealed nickel hydroxide‐based precursor provides an enhancement of the energy storage properties. These results provide an important approach for increasing the electrochemical activity of composites by the combined effect of interfacial mismatch and pseudocapacitance, as well as understandings of the mechanism of the enhancement of the composite electrode properties.