Lithium-based batteries are an important source of energy for autonomous systems and sensors. The objective of this research is to perform experiments necessary to understand the mechanisms responsible for lithium-ion battery safety. Recent research results show temperature dependent morphologies of metallic lithium with implications for improving lithium-ion battery safety.
The root cause of lithium ion battery (LIB) failures lack fundamental understanding, as highlighted by the unanticipated in-flight fires of lithium-ion batteries on the Boeing 787 Dreamliner. One suspect is the formation of metallic Lithium dendrites, which can puncture the separator and form a short circuit between the cathode and anode.
Using NRL’s new environmental laboratory in the Laboratory for Autonomous Systems Research, in-situ optical microscopy is employed for imaging Li dendrites. Two dendrite morphologies have been observed during plating of metallic lithium anodes in a typical commercial electrolyte. At ambient temperature (23°C) solid Li electrodeposits agglomerate to form a loosely-packed structure. At sub-ambient (-5°C) temperature, similar to what was experienced by the Dreamliner batteries, the electro-deposited Li extrudes into a continuous wire ball structure.
Further studies are ongoing to better understand the temperature-dependent stability of dendrites formed over a range of temperatures, and determine the link between instability at the electrode/electrolyte interfaces leading to nucleation and growth of lithium dendrites and the susceptibility to battery failure.
Dr. Corey Love
Alternative Energy Section
Naval Research Laboratory
Washington DC 20375