Studies of lithium dendrite control and electrode design for lithium metal battery

Abstract

Recently, electric vehicles have been attracting attention due to climate change, and demand for increasing mileage and driving time is increasing. For this purpose, it is necessary to develop materials having a high energy density, and there is an attempt to replace the commercial graphite anode with the lithium metal anode. Lithium metal has lowest redox potential and has a high theoretical capacity of 3860 mAh $g^{-1}$ which can improve energy density of secondary batteries. However, there are problems with the lower reversibility due to electrolyte consumption caused by high reactivity of lithium metal and the growth of dendrite during cell driving, which causes stability problems. Thus, to overcome low reversibility and stability, the design of electrodes that can control the growth of lithium dendrites is essential. In this thesis, two methods were used to improve the performance of lithium metal batteries. First, using an alloy with a small amount of magnesium in lithium metal, a mechanism for suppressing lithium dendrite growth through control of surface energy while maintaining physical/chemical properties of lithium was identified. Secondly, the lithium metal anode surface was protected by using a MXene-graphene oxide-polymer composite film, and the performance was improved by utilizing the strengths of A and B respectively. These studies suggest that various and integrated approaches are needed to solve the problems of battery components.