Ultra-thick, dense dual-encapsulated Sb anode architecture with conductively elastic networks promises potassium-ion batteries with high areal and volumetric capacities
Zhonggang Liu, Xi Liu, Bingchun Wang, Xinying Wang, Dongzhen Lu, Dijun Shen, Zhefei Sun, Yongchang Liu, Wenli Zhang, Qiaobao Zhang, Yunyong Li
Abstract
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) Ti3C2Tx MXene and graphene dual-encapsulated nano-Sb monolith architectures (HD-Sb@Ti3C2Tx-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 Ti3C2Tx and graphene; these effectively mitigate against volume expansion and the pulverization of Sb, offering good electrolyte penetration and rapid ionic/electronic transmission. Ti3C2Tx 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.