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The performance of Zn-Air battery (ZAB) is often limited by sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reactions (OER). In this work, a flower-like porous carbon is designed for the synthesis of the Co/Zn/Mn@NC. Due to a highly porous structure and abundant active sites, the as-prepared Co/Zn/Mn@NC-800 shows a half-wave potential of 0.86 V for ORR, and an overpotential of 360 mV for OER at 10 mA/cm2, suggesting an excellent bifunctional catalytic activity. The ZAB with Co/Zn/Mn@NC-800 delivers a power density of 163 mW/cm2 and a specific capacity of 832 mA h/g Zn , higher than that with Pt/C + RuO 2 (147 mW/cm2 and 802 mA h/g Zn). Moreover, the Co/Zn/Mn@NC-800-based ZAB has a superior long-term stability with a negligible decline of efficiency (0.3%) after 534 cycles (>150 h). These results suggest that the synthesized Co/Zn/Mn@NC catalyst has a great potential for the practical application in ZABs. [Display omitted] • Flower-like porous carbon for the synthesis of trimetallic Co/Zn/Mn@NC. • The Co/Zn/Mn@NC-800 shows a half-wave potential of 0.86 V for ORR. • The Co/Zn/Mn@NC-800 has an overpotential of 360 mV for OER at 10 mA/cm2. • Zinc-air battery with Co/Zn/Mn@NC-800 has a power density of 163 mW/cm2. • The Co/Zn/Mn@NC-800-based zinc-air battery has a superior long-term stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • The TMSCH-derived CEI/SEI films effectively protect NCM811 cathode and Li anode. • The detrimental effects of HF are alleviated by Si-O functional group of TMSCH. • The cyclic performance of the Li/NCM811 cell with TMSCH is significantly enhanced. • The growth of Li dendrites is inhibited by the TMSCH-derived double-layer SEI film. Li metal batteries (LMBs) coupled with Ni-rich materials are promising candidates for next-generation high-energy-density lithium batteries. However, due to the inferior stability of cathode/solid-electrolyte interphases (CEI/SEI) and aggressive chemistry of Ni-rich cathode materials, Li metal anode (LMA) and LiPF 6 -based carbonate electrolytes pose a threat to the achievement of high-energy-density LMBs. Herein, 1-(trimethylsilyloxy)cyclohexene (TMSCH) with functional groups (C=C, Si-O) as a novel multi-functional electrolyte additive is employed to regular the CEI/SEI films on the both Ni-rich cathode materials (LiNi 0.8 Co 0.1 Mn 0.1 O 2 , NCM811) and LMA surface, and scavenge detrimental hydrogen fluoride (HF) to enhance electrochemical performances of the Li/NCM811 batteries. Furthermore, the theoretical calculation, electrochemical measurements and physical characterizations demonstrate the feasibility and effectiveness of the strategy. Specially, the TMSCH-derived SEI film exhibits a hierarchical structure consisting of an organic-rich outer layer and a LiF-rich inner layer. Accordingly, the microcracks generation of NCM811 secondary particles, transition metal ions dissolution, lithium dendrite growth, parasitic reactions and HF generation of electrolyte are effectively addressed. As a result, with existence of the TMSCH additive, the capacity retention of Li/NCM811 batteries at 1C are remarkably enhanced from 68.2% to 84.9% at 30 °C and 64.2% to 85.8% at 45 °C. Furthermore, the Li/Li symmetric cells with TMSCH can stably cycle over 1000 h at 0.2 mA cm−2 and exhibit super-low overpotential of 75 mV at 1 mA cm−2. [ABSTRACT FROM AUTHOR]