Battery management is not a new concept—monitoring and control concepts were proposed as
early as the 1960s to improve battery safety. After years of intensive study, it remains a field
needing more research. This is not because we did not learn much during the past 50 years, we
did. But the subject of study is rapidly changing. The materials and structure of the battery
anode, cathode and electrolytes continue to evolve and improve, and the electrochemistry
and aging mechanisms also continue to change. The performance and capacity of batteries
degrade due to the disordering and deforming of electrode structure, decomposition of the
electrolyte, dissolution of metal, dendrite formation, and so on. The relative importance of these
mechanisms is battery-chemistry dependent, and the rate of degradation changes significantly
with many factors, including operating temperature, charge and discharge rate, and depth of
discharge. Finally, these aging mechanisms happen at different timescales, posing challenges
to data collection and analysis. The safety incidents of the Boeing Dreamliner battery systems
in 2012 remind us that much remains to be done before advanced high energy density battery
systems can be used safely and reliably in challenging applications such as aircraft and electric
vehicles