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A bilayer host electrode strategy for lithium metal anode to enable superior cycling performance and capacity utilization

Meng Yu,Xiaohui Ning

Li metal with ultra-high theoretical capacity is a promising anode for next-generation high-energy–density battery technologies. Nevertheless, the uncontrolled Li dendrite growth, continuous interfacial side reactions and irregular volume expansion bring about rapid capacity decay of Li metal anodes (LMAs). Herein, we design a bilayer host structure with an electronic conductivity gradient through a facile blade coating strategy to regulate Li deposition behavior. The electronic-insulative Si 3 N 4 top layer prevents the apical growth of Li dendrites and promotes the penetration of electrolytes into the host so as to lower electrode polarization. The carbon black/LiNO 3 mixed bottom layer creates mixed electronic-ionic conductive network to enhance the charge transfer kinetics of Li ions and lower Li nucleation barrier. Moreover, we first discover that the Si 3 N 4 protective layer avoids the cell failure resulting from the dissolution of LiNO 3 in ether electrolytes, enabling the Si 3 N 4 -C/LiNO 3 electrode to operate smoothly for over 600 cycles, delivering an average Coulombic efficiency of up to 98.65 %. Furthermore, the Si 3 N 4 -C/LiNO 3 -composited LMAs paired with 10.5 mg cm −2 LiFePO 4 cathodes achieve 200 stable cycles at a low N/P ratio of 1 under corrosive carbonate ester electrolytes, with an anode capacity utilization ratio as high as 50 %. This is the first report on the LiNO 3 -modified host materials that exhibit superior electrochemical properties in ether electrolytes, shedding a new light on the structural design of LMAs to enable high-energy–density Li metal batteries.