LiF/Fe composite for Ni-rich cathode prelithiation: Synthesis, bilayer structured electrode and lithium loss compensation

Prelithiation is an effective method to mitigate the active lithium loss in lithium-ion batteries. Compared to anode prelithiation, cathode prelithiation is more compatible with conventional manufacturing process. However, the existing prelithiation additives are costly to prepare and have limited shelf-life. In this study, LiF/Fe composite, which can be stably stored in air with high electrochemical, chemical and thermal stability, was successfully synthesized via the low-cost and readily available ball milling technique. LiF/Fe with well controlled microstructure was successfully used as prelithiation agent in LiNi0.8Co0.1Mn0.1O2 cathodes through the bilayer-structure. The LiF/Fe composite exhibits one-time delithiation capacity up to 400 mAh g−1 through conversion reaction between LiF and Fe, which not only replenishes the active lithium loss but also leads to stable cathode electrolyte interphase and integrated cathode structure, thereby improving overall electrochemical performance. The incorporation of LiF/Fe in the cathode results in significant increase in the capacity of the full cell by >10 %. Furthermore, the cycle stability is also improved, which works not only in LiNi0.8Co0.1Mn0.1O2||Graphite cell but also in anode-free lithium metal battery. This work offers an economic, efficient and promising cathode prelithiation solution to compensating for the active lithium loss and elevating the energy–density of rechargeable Li-ion batteries.