Mn-based layered/olivine composite-structure cathode for long-life lithium-ion batteries

Abstract

Mn-based Li-rich layered oxide (Mn-LLO) cathodes own promising potential for electrochemical energy-storage (EES) systems due to their cost-effectiveness, structural diversity, and high energy density. However, the longevity of these Mn-based materials remains a crucial challenge that hampers their adoption in grid-scale applications. To address this issue, the composite-structure outside of grain (CSOG) strategy integrated with layered/olivine structures is proposed for enhancing the stability of crystal structure, interfacial chemistry, and electrochemical cycling behaviors of Mn-LLOs. A series of cutting-edge microscopic and synchrotron techniques present the CSOG strategy that initiates the intensified particle surface, stable P−O bonding for layered structure, and robust electrode-electrolyte interphase. This multi-faceted reinforcement effectively bolsters interfacial stability for both pristine and electrochemical cycling. As a result, the Mn-based CSOG cathodes realize superior capacity retention over 1000 cycles with capacity decay of ∼0.009% per cycle in pouch cells. Crucially, enhanced interfacial behaviors in the CSOG cathodes inhibit elemental dissolution and deposition of Mn onto the anode and result in a ∼39% improvement in thermal stability compared to pristine Mn-LLOs. This innovative CSOG concept opens new avenues for designing highly stable Mn-based cathode materials, accentuating their potential for grid-scale EES applications.