Synergistic dual-additive regulated carbonate electrolyte stabilizes bidirectional interface for aggressive Ni-rich Li-metal full batteries

The escalating energy demands underscore the importance of Ni-rich Li-metal batteries (LMBs); however, their aggressive bidirectional electrode-electrolyte interfacial issues hinder the practical implementation. Overcoming the limited solubility (∼800 ppm) of lithium nitrate (LiNO₃) in commercially available carbonate electrolytes holds promise. Nevertheless, unintended effects caused by solubilizers raise emerging concerns. Herein, an additive solubilized additive strategy is introduced to synergistically stabilize the Ni-rich cathode and Li-metal anode (LMA) in carbonate electrolytes, where tris (2, 2, 2-trifluoroethyl) borate (TTFEB) as a solubilizer utilizes its electron-deficient B atom to snatch electron-rich NO₃^- anion of insoluble LiNO₃ and thus forms a unique TTFEB-LiNO₃ solvation structure in carbonate electrolytes. Valuably, the dual-additive electrolyte facilitates the formation of a robust LiF/Li₃N-rich solid electrolyte interphase on LMA and a thin, uniform F, B, N-rich cathode electrolyte interphase on Ni-rich cathode, effectively suppressing the breeding of Li dendrites and mitigating the structure degradation of Ni-rich cathode. Consequently, the full cell, featuring a thin Li anode (50 µm) and a high-loading NCM811 cathode (4.04 mAh cm⁻²) in the dual-additive electrolyte, demonstrates a notable capacity retention of 81.5 % after 140 cycles. This work reveals the intricated LiNO₃-carbonate solvation chemistry, inspiring further advancements in electrolyte engineering for practical LMBs.