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 ) Ti 3 C 2 T x MXene and graphene dual-encapsulated nano-Sb monolith architectures (HD-Sb@Ti 3 C 2 T 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 Ti 3 C 2 T x and graphene; these effectively mitigate against volume expansion and the pulverization of Sb, offering good electrolyte penetration and rapid ionic/electronic transmission. Ti 3 C 2 T 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.
Xu Yang,Rongyu Zhang,Shifeng Xu,Dan Xu,Jia Ma,Zhongyu Zhang,Shu Yang
Graphical Under cover : A graphene/amorphous carbon restriction structure is designed for an Sb anode, in which the anode is protected from pulverization and aggregation, thus leading to the excellent stability and long lifespan of Sb in K-ion batteries. Sb-based materials have attracted much attention owing to their ability to undergo a multi-electron alloy reaction with K + . However, there are still the serious problems of volume change and aggregation of particles, which lead to rapid capacity fading and a limited lifespan. In this work, a graphene/amorphous carbon restriction structure is proposed, in which the amorphous carbon layer on the surface of Sb nanoparticles can protect the particles from pulverization, and the graphene can buffer the volume change of the material. In addition, the conductive network formed by the dual carbon structure effectively improves the rate performance of the material. Thus, the material delivers a high capacity of 550 mA h g −1 at 100 mA g −1 , a rate capability of 370 mA h g −1 at 2000 mA g −1 , and a long lifespan of 350 cycles without significant capacity fading. The dual carbon strategy proposed offers a reference for the design of high-performance anode materials.
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