A Thermodynamic Reassessment of Lithium-Ion Battery Cathode Calorimetry

Abstract

This work demonstrates how staged heat release from layered metal oxide cathodes in the presence of organic electrolytes can be predicted from basic thermodynamic properties. These prediction methods for heat release are an advancement compared to typical modeling approaches for thermal runaway in lithium-ion batteries, which tend to rely exclusively on calorimetry measurements of battery components. These calculations generate useful new insights when compared to calorimetry measurements for lithium cobalt oxide (LCO) as well as the most common varieties of nickel manganese cobalt oxide (NMC) and nickel cobalt aluminum oxide (NCA). Accurate trends in heat release with varying state of charge are predicted for all of these cathode materials. These results suggest that thermodynamic calculations utilizing a recently published database of properties are broadly applicable for predicting decomposition behavior of layered metal oxide cathodes. Aspects of literature calorimetry measurements relevant to thermal runaway modeling are identified and classified as thermodynamic or kinetic effects. The calorimetry measurements reviewed in this work will be useful for development of a new generation of thermal runaway models targeting applications where accurate maximum cell temperatures are required to predict cascading cell-to-cell propagation rates.

Are solid-state batteries safer than lithium-ion batteries?

“…Schematics of the configurations explored for safety are shown in Figure 1. The layers are to scale using a representative thickness for each material, based on the advanced format in 20,21 It is expected that moving to a higher Ni content cathode will result in greater heat release in some scenarios due to increased capacity and reactivity. The LE solvent used throughout this work is ethyl methyl carbonate (EMC) as it represents a good middle ground between heat release and molar mass compared with other popular solvents.…”

From material properties to multiscale modeling to improve lithium-ion energy storage safety

“…35 It is likely that the first exothermic cathode transformation observed is related to this formation of a lithium-containing spinel. 21,36,37 Subsequent heat release can occur with reactions between the electrolyte and oxygen atoms released from the cathode. This involves the conversion from MO 2 or LiM 2 O 4 to a spinel M 3 O 4 and/or a rock salt MO.…”

“…This involves the conversion from MO 2 or LiM 2 O 4 to a spinel M 3 O 4 and/or a rock salt MO. 21,[36][37][38][39] The oxygen release must occur at the surface and excess metal cations will need to move further into the bulk. 30 The exact limiting physics associated with this oxygen atom loss to react with the electrolyte is not well described at this point.…”

“…This accounts for the observation of multiple exotherms in calorimetry of highly charged cathodes shown in Figure 1c. 21,37 Early commercialized cathodes were largely based on cobalt, LiCoO 2 , and have been reasonably well characterized. 35,38,39,41 Using nickel as the transition metal gives a higher energy density, but yields a less thermally stable cathode material than needed (with similarly reduced cycle life).…”

Combined Thermal Runaway Investigation of Coin Cells with an Accelerating Rate Calorimeter and a Tian-Calvet Calorimeter

“…In a recent work, Shurtz [21] demonstrated that results from calorimetry measurements and thermodynamic calculations can constitute the basis for advanced thermal runaway models which are able to predict the heat release from layered metal oxide cathodes in contact with organic electrolytes.…”