Multiscale Micro-Nano Hierarchical Porous Germanium with Self-Adaptive Stress Dispersion for Highly Robust Lithium-Ion Batteries Anode

The manipulation of stress in high-capacity microscale alloying anode materials, which undergo significant volumetric variation during cycling, is crucial prerequisite for improved their cycling capability. In this work, an innovative structural design strategy is proposed for scalable fabrication of a unique 3D highly porous micro structured germanium (Ge) featuring micro-nano hierarchical architecture as viable anode for high-performance lithium-ion batteries (LIBs). The resultant micro-sized Ge, consisting of interconnected nanoligaments and bicontinuous nanopores, is endowed with high activity, decreased Li⁺ diffusion distance and alleviated volume variation, appealing as an ideal platform for in-depth understanding the relationship between structural design and stress evolution. Such a micro-sized Ge being highly porous delivers a record high initial Coulombic efficiency of 92.5%, large volumetric capacity of 2,421 mAh cm⁻³ at 1.2 mA cm⁻², exceptional rate capability (805.6 mAh g⁻¹ at 10 Ag⁻¹) and cycling stability (over 90% capacity retention after 1000 cycles even at 5 A g⁻¹), largely outperforming the reported Ge-based anodes for LIBs. Furthermore, its underlying Li storage mechanism and stress dispersion behavior are explicitly revealed by combined substantial in situ/ex situ experimental characterizations and theoretical computation. This work provides novel insights into the rational design of high-performance and durable alloying anodes toward high-energy LIBs. © 2024 Wiley-VCH GmbH.