Turning waste into treasure: a dual-modulation strategy for Ni-rich cathode towards moderate Li/Ni mixing and Li2CO3 encapsulation to enhance lithium storage

Abstract

Ni-rich cathodes (Ni ≥ 70%) with high specific capacities emerge as promising candidates for long-range lithium-ion batteries (LIBs). Nevertheless, their practical application is severely limited by two unresolved challenges: structural degradation from uncontrolled Li/Ni mixing and interfacial instability exacerbated by air/electrolyte corrosion. Herein, we propose a dual-modulation strategy to synthesize a stable Ni-rich cathode via carboxylate-based metal–organic frameworks (MOFs)-derived precursors, whereby oxygen vacancies in the precursors induce controlled moderate Li/Ni mixing, while their enhanced specific-surface-area property enables dense amorphous Li₂CO₃ encapsulation. The optimal Li/Ni mixing harnesses the Ni pillar effect to stabilize the structure of cathodes upon cycling. Additionally, amorphous Li₂CO₃ coating serves not only as a thermodynamically stable and air-impermeable protective layer for the cathodes, but as a transformative precursor for an F-rich cathode electrolyte interphase (CEI) which enhances interfacial stability and electrochemical properties. This dual-modulated cathode delivers a high discharge capacity of 215.1 mA h g⁻¹ at 0.1 C, retains 84.9% capacity after 200 cycles at 1 C in half cells, and achieves 96.0 mA h g⁻¹ at 8 C in full-cell tests. Furthermore, we unravel the potential mechanism of Ni pillar effect from optimal Li/Ni mixing and track the evolution mechanism of Li₂CO₃ coating into F-rich CEI. This work offers advanced perspectives for the controllable cation disordering engineering and rational design of surface residual lithium compounds in Ni-rich cathodes, thereby providing new guiding principles for protecting high-capacity cathodes in energy storage devices.