Atomic-Level Shock-Absorbing Spring: Curvature-Driven Mechanical Homogenization of Hard Carbon for High-Stability Sodium-Ion Batteries

In sodium-ion batteries, the insufficient cycling stability of hard carbon anode stems from the physical essence of electrochemical-mechanical coupling failure. Herein, a highly heterogeneous state with extensive weak regions was transformed into a rigid skeleton by adapting a metal-catalyzed carbon structure reconfiguration strategy. Crucially, the introduction of long-range ordered curvature features establishes a pool of atomic-level shock-absorbing spring systems within the carbon network. It not only reversibly accommodates mechanical strain along the z-axis direction but also homogenizes the localized stress of the xy plane. As the balanced enhancement of mechanical properties was achieved across multiple dimensions, electrochemical tests confirmed that the architected rigid framework shows no capacity degradation after 1000 cycles at a current density of 2 A g-1. Thus, our study provides a new design paradigm for developing high-performance anodes via a mechanical homogenization design of hard carbon.