Rational design of NiO/NiSe₂@C heterostructure as high-performance anode for Li-ion battery

Biphasic or multiphase heterostructures have promising futures in advanced electrode materials for energy-related applications because of their desirable synergistic effects. Here we prepared a rational NiO/NiSe₂@C heterostructure microsphere through carbonization, selenization, and oxidation using Ni-MOF as a precursor. Electrochemical studies were conducted to examine the Li⁺ storage characteristics, and density functional theory (DFT) was utilized to comprehend the underlying mechanism. When employed as the anode for LIBs, the NiO/NiSe₂@C showed a high specific capacity and long-term cyclic stability, with a specific capacity of 992 mAh g⁻¹ for 600 cycles at a current density of 0.2 A g⁻¹. The NiO/NiSe₂@C exhibits a significantly enhanced lithium-ion diffusion coefficient (D_Li⁺) value. The DFT results show that an electron-rich area forms at the NiO/NiSe₂ heterointerface, where the metalloid selenium transfers electrons to the oxygen atoms. The lithiation reactions were improved dramatically by redistributing interfacial charges, which can trigger a built-in electric field that dramatically promotes the capacitance contribution of electrode materials, enhances the lithium storage capacity, and accelerates the ion/electron transmission. The rational synthesis of NiO/NiSe₂@C heterostructure can provide an idea for designing novel heterostructure anode materials.