Powering devices as small as smartphones to those as large as electric vehicles, the rechargeable battery is a familiar technology to consumers. Work in the field of battery research continues, however, as researchers struggle to improve the efficiency and longevity of rechargeable batteries. State-of-the art Li-ion batteries offer fast charging but suffer from low power density. Research has therefore focused on optimization of battery anodes, cathodes, electrolytes, and even on replacement of lithium itself with other metals like sodium.
Of these alternatives, lithium metal batteries, have been studied since the 1960s and 1970s. Lithium metal batteries intrinsically offer higher energy density than Li-ion batteries, but according to Shirley Meng, a professor at UC San Diego Jacobs School of Engineering, a lot of technical challenges have prevented its commercialization.
One challenge is the presence of inactive lithium at the solid electrolyte interface (SEI) that forms each time a lithium metal battery discharges. Over several cycles, the battery forms such a significant amount of inactive lithium that it loses the ability to recharge. For years, researchers have thought that both lithium metal blocked from the conductive pathways by the SEI and lithium ion compounds formed in the SEI contributed to inactive lithium.
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