Carbon‐encapsulated anionic‐defective MnO/Ni open microcages: A hierarchical stress‐release engineering for superior lithium storage

Abstract

Abstract Rational manipulation of multicomponent materials into a sophisticated architecture is a prerequisite for developing lithium‐ion batteries. However, mechanical diffusion‐induced strain accumulation leads to sluggish diffusion kinetics and anomalous structure instability, further resulting in inferior long‐term cyclability and rate performance. Herein, the von Mises stress distribution on open microcages composed of secondary nanoparticles (OCNs) is mechanically investigated by finite element simulation, which elucidates the pronounced stress‐release effect on OCNs architecture. Afterward, a facile metal–organic framework‐derived methodology is proposed for constructing multihierarchical carbon‐encapsulated oxygen vacancy‐enriched MnO/Ni OCNs (OV‐MnO/Ni OCNs). Due to structural and compositional integration, the OV‐MnO/Ni OCNs achieve extraordinary lithium storage performance with excellent reversible capacity (1905.1 mAh g−1 at 0.2 A g−1), ultrahigh cycling stability (1653.5 mAh g−1 at 2 A g−1 up to 600 cycles), and considerable rate capability (463.3 mAh g−1 even at 10 A g−1). The primary lithium storage mechanisms are further systematically determined by experimental and theoretical investigations. The enriched oxygen vacancies, metallic Ni configuration, and N‐doped carbonaceous matrix provide more active sites, construct omnidirectional diffusion pathways, suppress volume expansion, and boost electronic conductivity, thus yielding an exceptional diffusivity coefficient and expedited electrochemical kinetics. This study offers profound insights for the elaborate design of multicompositional electrodes into a mechanical stress‐release structure toward advanced energy storage application and development.

Keywords

• DFT calculations
• finite element simulation
• lithium‐ion batteries
• metal–organic frameworks
• oxygen vacancies