Promises and Challenges Facing Lithium Metal Batteries

Abstract

Nowadays, due to rapid development in technology, regardless of automobile industry, portable devices and energy storage system, the requirement of energy density, capacity and operating voltage becomes higher and higher. Traditionally, graphite anode with low capacity is limited to develop advanced lithium ion battery(LIB) and is hard to achieve the high-tech product specification; therefore, battery industries have started to focus on silicon-carbon composite materials in substitution. However, it also faces its limitation to achieve energy density of 700 Wh L-1. Using lithium metal as the anode material seems to be the only route to achieve 1000 Wh L-1 due to its extremely high capacity (3860 mAh g-1), lightness (0.59 g cm-3), and low reduction potential (-3.04 V). Consequently, more and more battery experts and researchers have devoted themselves to lithium metal battery (LMB) research. Nevertheless, lithium as active metal easily reacts with electrolyte producing poor solid electrolyte interphase (SEI) with high internal resistance leading to low coulombic efficiency and short cycle life. During charge and discharge process, lithium plating and stripping leads to non-even deposition. As a further matter, under extreme environment, such as high current density and charge density, dendritic dendrite easily forms resulting in safety issue including failure of separator and short circuit. Based on the above issues, lithium metal battery could be hardly commercialized. Therefore, battery design should be aimed at lithium metal anode instead of traditional LIB anode. First of all, innovative electrolyte system which benefits the formation of highly-stable SEI should be established. Secondly, the artificial SEI on lithium anode is served as the first line of defense against dendrite due to excellent mechanical strength and elasticity. Finally, it is important to develop a structured anode for improving lithiophilic property, uniform electric field and solving volume expansion issue.