Air‐Stable Lithium Spheres Produced by Electrochemical Plating

Lithium metal is an ideal anode for next‐generation lithium batteries owing to its very high theoretical specific capacity of 3860 mAh g−1 but very reactive upon exposure to ambient air, rendering it difficult to handle and transport. Air‐stable lithium spheres (ASLSs) were produced by electrochemical plating under CO2 atmosphere inside an advanced aberration‐corrected environmental transmission electron microscope. The ASLSs exhibit a core–shell structure with a Li core and a Li2CO3 shell. In ambient air, the ASLSs do not react with moisture and maintain their core–shell structures. Furthermore, the ASLSs can be used as anodes in lithium‐ion batteries, and they exhibit similar electrochemical behavior to metallic Li, indicating that the surface Li2CO3 layer is a good Li+ ion conductor. The air stability of the ASLSs is attributed to the surface Li2CO3 layer, which is barely soluble in water and does not react with oxygen and nitrogen in air at room temperature, thus passivating the Li core. Protective coat: Air‐stable lithium spheres formed in a CO2 environment at the carbon nanotube (CNT), Li2O, and CO2 triple point upon applying a negative potential. The high air stability is due to the formation of a Li2CO3 surface passivation layer.