A predictive theory on thermal runaway of ultrahigh capacity lithium-ion batteries

Ultrahigh capacity lithium-ion batteries (LIBs) with prudent safety measures are key to future transportation. The undesirable thermal events such as thermal runaway (TR) in LIBs can pose a direct risk to battery life and the consumers. In the present study, a set of new TR criteria are established by closely inspecting the relation between the rate of heat generation and dissipation to anticipate the TR at an early stage. From the proposed criteria, three alarming temperatures prior to TR are identified, such as the safe temperature limit T E (an intersection between heat generation curve and heat removal line), the maximum temperature limit T M (where second derivative of heat generation is zero), and the low temperature T C from the Semenov theory. For a safer battery operation, both the low and upper limit temperatures have to remain below the safety zone, i.e. T-M < T-E with T-C < T-E . The criteria are validated by implementing them on the ultrahigh capacity LIBs, which are subjected to the thermal abuse, wherein the rate of heat generation was determined from calorimetry. The state T-M < T-E indicates the first precursor to TR where a controlled measure can be taken to prevent the runaway. However, T-E <= T-M regarded as the critical state during which a self-sustaining reaction involving delithiated nickel-rich cathode, intercalated anode, and dissociated electrolyte progresses, resulting in an irreversible TR in the system. The validity of the proposed criteria is demonstrated, while additional work is considered in a broad class of batteries subjected to thermal abuse conditions for establishing a safety margin of operation.(c) 2023 The Author(s). Published by Elsevier Inc. on behalf of The Combustion Institute. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )

Automated summary

This study establishes a new set of criteria for predicting thermal runaway in lithium-ion batteries, which is crucial for ensuring the safety and performance of such batteries. The criteria identify key temperatures that need to be monitored to prevent unwanted thermal events. The validity of the criteria is demonstrated through testing on high-capacity batteries, and further work is suggested for establishing safety measures in different battery systems.