High-Energy-Density and Long-Lifetime Lithium-Ion Battery Enabled by a Stabilized Li₂O₂ Cathode Prelithiation...

Lithium-ion batteries (LIBs) typically suffer from large irreversible capacities caused by active lithium loss during formation of a solid electrolyte interface (SEI) at the anode side. Cathode prelithiation with preloaded additives has emerged as an effective strategy to solve the above issue. With ultrahigh theoretical capacity, Li₂O₂ serves as an excellent cathode prelithiation additive, whereas poor ambient stability limits its further development. In this study, we report a surface protection strategy to enable ambient processing of the Li₂O₂ additive. Li₂O₂ is well confined in poly(methyl methacrylate) (PMMA) nanofibers (P-Li₂O₂) via electrospinning, which exhibits greatly enhanced ambient stability compared with the unprotected one. Notably, when P-Li₂O₂ is preloaded in LiNi_0.5Co_0.2Mn_0.3O₂ cathodes (NCM-P-Li₂O₂), PMMA nanofibers remain stable during cathode slurry processing but readily dissolve in electrolytes and expose Li₂O₂ for effective electrochemical oxidation. Fabrication of P-Li₂O₂ allows systematic investigation of prelithiation behavior in full cells (NCM-P-Li₂O₂ cathodes paired with Si/Graphite anodes) and its impact on the electrochemical performance. Rational tuning of the prelithiation degree provides guidance for optimizing the amount of the cathode additive, which brings appealing cell lifetime and energy density.