Bond Softening and Elastic Confinement of Monolithic Dense Binary Alloys for High Volumetric Capacity of K‐Ion Battery Anodes

Abstract

ABSTRACT Two‐dimensional (2D) Sb─Bi alloys are considered as the promising high‐capacity and high‐rate anodes of potassium‐ion batteries, yet their practical application is limited by low density and structural degradation. Herein, we propose an intrinsic‐extrinsic dual‐stabilization strategy that integrates 2D binary Sb 0.6 Bi 0.4 nanosheets into 3D elastic graphene networks, constructing a highly dense monolithic architecture (HD‐Sb 0.6 Bi 0.4 @G). This design features with high density (2.6 g cm −3 ) and electrical conductivity (555.6 S m −1 ), delivering large volumetric capacity (1355.1 mAh cm −3 ) and high areal capacity (11.4 mAh cm −2 ) at an ultra‐high loading of 27.6 mg cm −2 , along with long‐term cyclability (65.4% capacity retention after 1500 cycles) and stable full‐cell performance. Experimental and theoretical analyses reveal that the Sb─Bi alloy exhibited “bond softening” with the optimized interlayer spacing and moderate bond energy, facilitating rapid K + diffusion and buffering strain. Furthermore, the elastic graphene network provides nanoscale confinement, accommodating volume expansion and preserving structural and electrical integrity. Strong electronic coupling at the alloy‐graphene interface further reduces K + adsorption and diffusion energy barriers, enabling fast ion transport under the high‐loading anodes. This intrinsic‐extrinsic synergy between binary‐alloy bond softening and nanoscale elastic confinement provides a universal strategy for compact, high‐loading electrodes with high volumetric and areal energy storage.