Toward real-time monitoring of lithium metal growth and dendrite formation surveillance for safe lithium metal batteries

Abstract

Li metal has been regarded as one of the promising anode materials of the future due to its high specific capacity and low redox potential. To guarantee its safety and take full advantage of the capacity of Li metal batteries, it is important to understand the growth location, deposition uniformity, and degree of compactness of lithium metal deposition in the anode area during the operation of Li metal batteries. However, no research has been reported on the monitoring of lithium plating within the anode structure at the micro-level. Herein, we propose a new concept for the real-time monitoring of Li metal growth and the early surveillance of Li dendrites, which was demonstrated by simply adopting an alternating dielectric/conductive lamella structure. Within our alternated carbon nanofiber (CNF) scaffold and polyimide (PI) film host (CNF–PI host), the dielectric PI layer can block the direct electron transportation pathway between adjacent conductive CNF frameworks, thus guiding the Li metal plating in a more desirable stepwise “bottom-up” manner. The Li growth position could be detected in real time by monitoring the voltage between each conductive CNF layer and the counter electrode. And the Li deposition capacity inside each layer of CNF was further obtained, which reflected the stability of the Li deposition process. Meanwhile, due to the optimized Li deposition manner, a composite Li anode with this functional host shows excellent electrochemical performance. The full cell based on this functional Li metal anode with a LiNi_0.8Co_0.1Mn_0.1O₂ cathode shows excellent cycling stability under both a high current density of 3.6 mA cm⁻² (1C rate) and areal capacity of 3.18 mA h cm⁻².