Ultra-thick, dense dual-encapsulated Sb anode architecture with conductively elastic networks promises potassium-ion batteries with high areal and volumetric capacities

Ultra-thick, dense alloy-type anodes are promising for achieving large areal and volumetric performance in potassium-ion batteries (PIBs), but severe volume expansion as well as sluggish ion and electron diffusion kinetics heavily impede their widespread application. Herein, we design highly dense (3.1 ​g ​cm⁻³) Ti₃C₂T_x MXene and graphene dual-encapsulated nano-Sb monolith architectures (HD-Sb@Ti₃C₂T_x-G) with high-conductivity elastic networks (1560 ​S ​m⁻¹) and compact dually encapsulated structures, which exhibit a large volumetric capacity of 1780.2 ​mAh cm⁻³ (gravimetric capacity: 565.0 ​mAh g⁻¹), a long-term stable lifespan of 500 cycles with 82% retention, and a large areal capacity of 8.6 ​mAh cm⁻² (loading: 31 ​mg ​cm⁻²) in PIBs. Using ex-situ SEM, in-situ TEM, kinetic investigations, and theoretical calculations, we reveal that the excellent areal and volumetric performance mechanism stems from the three dimensional (3D) high-conductivity elastic networks and the dual-encapsulated Sb architecture of Ti₃C₂T_x and graphene; these effectively mitigate against volume expansion and the pulverization of Sb, offering good electrolyte penetration and rapid ionic/electronic transmission. Ti₃C₂T_x also decreases the K⁺ diffusion energy barrier, and the ultra-thick compact electrode ensures volumetric and areal performance. These findings provide a feasible strategy for fabricating ultra-thick, dense alloy-type electrodes to achieve high areal and volumetric capacity energy storage via highly-dense, dual-encapsulated architectures with conductive elastic networks.