Advantageous Multifunctional Surface Modification of Layered Nickel-Rich NCMA Cathodes Enables Superior Cyclability and Interfacial Properties in Lithium Metal Batteries

Transition metal oxides (TMOs) rich in nickel (Ni) are significantly advancing the field of energy storage, particularly when combined with lithium metal anodes (LMAs). While the instability of Ni-rich cathodes poses challenges for large-scale commercialization, we propose a compelling solution: modifying layered oxide materials with multifunctional coatings. In our research, we enhanced Ni-rich Li(Ni_0.9Co_0.04Mn_0.03Al_0.03)O₂ (LNCMA90) particles by applying a lithiated Nafion polymer (LNf). This innovative coating stabilizes the electrolyte/electrode interface and forms a hybrid cathode electrolyte interphase (CEI) layer, improving Li⁺ ion transport and mechanical stability of the LNCMA90 material. Advanced characterization techniques, such as transmission electron microscopy (TEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS), confirmed the establishment of the stable CEI layer on the LNf-LNCMA90 electrode. Notably, the LNf-LNCMA90//Li cell retained 78.42% of its initial discharge capacity after 500 cycles at 1C/1C cycling, a substantial improvement over the 64.48% retention observed in the uncoated LNCMA90 (pr-LNCMA90)//Li cell. Furthermore, it maintained 75.22% of its capacity after 300 cycles at 0.5C/5C. In situ calorimetric studies demonstrated that the LNf-LNCMA90 cathode generated considerably less total heat, at 38 and 41 J g^-1, during charging and discharging at 1C/1C and 30 °C compared to its uncoated counterpart, which produced nearly 1.5 times more heat. In summary, the exceptional performance of the LNf-LNCMA90//Li cell can be attributed to the robust hybrid CEI layer that stabilizes the Ni-rich oxide structure, especially for Ni contents exceeding 90%. This advancement holds great promise for the future of lithium metal batteries (LMBs) and meets the increasing demands of the energy storage industry.