| 초록 |
Conventional lithium ion batteries (LIBs) based on intercalation chemistry are dominating the current rechargeable battery applications in consumer electronics, electric vehicles and grids. However, the exponential growth of renewable energy sources and the faster-evolving technological advances in these fields necessitate a greater leap in rechargeable battery technology than the current step-wise improvements we encounter in LIBs. This demands a radical change in cell chemistry and/or cell design to achieve higher energy density. Lithium metal batteries (LMBs), where lithium metals are used as the anode instead of conventional intercalation-type carbon materials, are one of the viable and promising options due to their higher theoretical capacity of 3860 mAh g-1 (vs. 372 mAh g-1 for graphite), low density and low redox potential (-3.04 V vs. standard hydrogen electrode). However, lithium metals are highly reactive in presence of organic electrolytes and form passivation layer known as solid electrolyte interface (SEI), which irreversibly consumes active lithium ions and depletes electrolyte. Moreover, infinite volume change associated with lithium plating/stripping process induces repetitive breakage and re-formation of SEI layer resulting in continuous consumption and depletion of electrolyte and lead to cycle fading and poor Coulombic efficiency. Another critical factor is the formation of dendritic structures induced by inhomogeneous charge distribution on the electrode/electrolyte interface due to surface heterogeneities. Such dendritic structures can pierce through the separator membrane and cause short circuit, which can lead to thermal runaway and potential safety hazards. |
