Bottlebrush polymer additive for lithium metal batteries

Abstract

Recent increases in demand for electric vehicles and advancements in various portable electronic devices have brought attention to lithium metal batteries, which have high energy density and the highest theoretical capacity. However, lithium metal batteries have a problem in that lithium ions are unevenly electrodeposited during the charging and discharging processes of the battery, resulting in the growth of lithium dendrites on the surface of lithium metal. The formation of dendrites on the electrode surface can result in issues such as thermal runaway and explosion due to short, as well as a decrease in battery efficiency and a reduction in lifespan due to various side reactions. Consequently, research efforts actively address these problems in lithium metal batteries through solid electrolytes, lithium anode protective layers, and electrolyte additives. Among these, electrolyte additive research offers the advantage of achieving significant improvements in electrochemical properties with infinitesimal amounts of additives. In this study, bottlebrush polymers (BBP) with polyethylene glycol (PEG) as side chains were synthesized and utilized as an electrolyte additive for lithium metal batteries. These bottlebrush polymer additives make homogeneous lithium ion nucleation sites on the lithium metal surface and play a crucial role in ensuring uniform lithium-ion flux control. Consequently, it facilitates the uniform deposition of lithium ions and realizes long-term stable cycling characteristics for lithium metal batteries.