Construction of hierarchical structured dual-shell hollow polyhedra NiCo₂O₄ based on Ti₃C₂T_x for advanced lithium-ion...

The development of lithium/sodium ion hybrid capacitors has been constrained by the dynamic disparity between the anode and cathode, in conjunction with the volume expansion of the anode material during the cycling phase. In this study, a dual-shell dodecahedral structure NiCo₂O₄ composite was fabricated by combining it with hydrofluoric acid-etched Ti₃C₂T_x lamellar material. The NiCo₂O₄ dual-shell dodecahedron structure manifests a substantial specific surface area and more active sites. Concurrently, by functioning as an ion buffer layer, the dual-shell structure mitigates volumetric variations during repeated ion insertion and extraction cycles while preserving exceptionally high-rate capabilities. Incorporating the layered structure of MXenes material is an effective method of mitigating the volume expansion of NiCo₂O₄, which in turn diminishes the generation of internal stress. Furthermore, the composite exhibits accelerated ion transport and enhanced conductivity, which ultimately enhances its cycling performance. In the Lithium Ion Battery (LIB) and Sodium Ion Battery (SIB) tests, the NiCo₂O₄-D1/Ti₃C₂T_x materials exhibited remarkable rate performance, with a capacity of 1570 mAh·g^-1 at 0.1 A·g^-1 in LIB and 705.6 mAh·g^-1 at 0.1 A·g^-1 in SIB. Subsequently, the composite material and AC were assembled into Lithium-Ion Hybrid Capacitor (LIHC) and Sodium-Ion Hybrid Capacitor (SIHC) for electrochemical testing. The NiCo₂O₄-D1/Ti₃C₂T_x//AC LIHC demonstrated a maximum energy density of 128.8 Wh·kg^-1 at a power density of 148.3 W·kg^-1, accompanied by an optimal capacity retention rate (92.1% after 5000 cycles at 2 A·g^-1). The SIHC achieves an energy density of 136.8 Wh·kg^-1 at a power density of 144.0 W·kg^-1 and exhibits a capacity retention rate of 83.6% following 5000 cycles at 2 A·g^-1. These findings proffer a novel alternative and furnish profound insights into the design and progression of electrode materials within high-performance electrochemical energy storage apparatuses.