A Novel Hierarchical Structure of SnCu₂Se₄/d-Ti₃C₂T_x/NPC for a Lithium/Sodium Ion Battery and Hybrid Capacitor with Long-Term Cycling Stabilities

To alleviate kinetics imbalance and capacity insufficiency simultaneously, a novel hierarchical structure (SnCu2Se4/d-Ti3C2Tx/NPC) composed of delaminated Ti3C2Tx, SnCu2Se4 nanoparticles, and N-doped porous carbon layers is designed as a battery-type anode for lithium/sodium ion hybrid capacitor (LIC/SIC). The combination of SnCu2Se4 nanoparticles with high specific capacity, d-Ti3C2Tx with accelerated ion diffusion path, and NPC with enhanced electronic conductivity makes the SnCu2Se4/d-Ti3C2Tx/NPC composite possess excellent cycling stabilities in half-cell lithium-ion and sodium-ion batteries (LIB and SIB), with capacities of 114 mAh g–1 after 6000 cycles at 10 A g–1 for LIB and 296 mAh g–1 after 900 cycles at 1.0 A g–1 for SIB. The rate performance is also outstanding, with recovered capacity of 738 mAh g–1 at 0.1 A g–1 after cycles at current densities up to 50 A g–1 for LIB. Subsequently, LIC and SIC based on the SnCu2Se4/d-Ti3C2Tx/NPC anode and activated carbon cathode exhibit high energy densities of 147.9 and 158.6 Wh kg–1 at a power density of 100 W kg–1, respectively. They also possess distinctive long lifespans with capacity retentions of 78 and 81% after 10,000 cycles at 1.0 A g–1, respectively, demonstrating the feasibility of SnCu2Se4/d-Ti3C2Tx/NPC toward energy devices requiring high energy density, power density, and long-term stability.