Abstract
The severe lithium (Li) dendrite growth leads to poor cycling stability and serious safety hazards of Li metal batteries, which completely impedes their practical applications. Herein, a novel Li nucleation-diffusion-growth mechanism based on Li-Sn alloy/Li3N electrolyte (LS/LN) composite interface layer is proposed, which synergistically guides the horizontal deposition of Li to suppress the vertical growth of Li dendrite and side reactions with the electrolyte. The lithiophilic Li-Sn alloy captures Li ions to nucleate preferentially on the alloy sites, and simultaneously the Li3N with low diffusion energy barrier and high Li-ion conductivity efficiently transports Li ions to nucleation sites during Li plating, consequently promoting the Li horizontal deposition. As a result, the LS/LN-Li symmetric cells can stably cycle 1600 h even at a high current density of 5 mA cm−2 and deposition capacity of 5 mA h cm−2. The LiFePO4∣LS/LN-Li cells with a high loading of 8.2 mg cm−2 present a high capacity retention of 93.4% after 1000 cycles, much higher than that using bare Li (64.8%). Furthermore, the LiNi0.8Co0.1Mn0.1O2∣LS/LN-Li cells present more excellent cycling stability than the cells using bare Li. The Li nucleation-diffusion-growth mechanism opens a promising route to solve the challenge of the vertical growth of Li dendrite and achieve highly stable Li metal batteries.
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