In-Operando Isothermal Microcalorimetry to Accelerate Screening of New Battery Chemistries

Abstract

Screening new cell chemistries using traditional electrochemical methods is a time prohibitive process that significantly slows the pace of research. These methods involve cycling the cell until signs of degradation or sufficient capacity fade are evident, and typically take months to complete. In-operando isothermal microcalorimetry is an established but underutilized technique for measuring the activity of parasitic, or non-reversible reactions during charge cycling [1,2,3,4]. A parasitic reaction is a blanket term for any side reactions that occur within a battery, including solvent breakdown, lithium plating, self-discharge reactions, and growth or decomposition of the solid electrolyte interphase. Battery formulations with high parasitic heat are strongly correlated with early cell failure. Compared to electrochemical cycling, the average parasitic heat over the full voltage range can be determined in a time frame as low as 2 weeks, allowing researchers to realize a time savings up to 75%. Additional time savings are also possible if only a narrow voltage range is of interest.In this study, we present results that demonstrate the measurement of the parasitic heat of a commercial 18650 lithium-ion battery using the TA Instruments Battery Cycler Microcalorimeter Solution. This method involves slow galvanostatic cycling at isothermal conditions with a simultaneous measurement of heat flow, voltage, and applied current. The parasitic heat is isolated from the total heat flow using the Integration-Subtraction method, with calculations performed automatically by the software [1]. The coulombic efficiency is also measured per cycle, showing an inverse relationship to the parasitic power. As a screening tool, this data could be used to select battery formulations most likely to meet performance goals in long-term cycling experiments, rather than wasting valuable time and lab space on a trial-and-error approach. The results highlight how in-operando isothermal microcalorimetry is a powerful screening tool for investigating the efficiency of new cell chemistries and electrolyte formulations in a fraction of the time compared to traditional methods.[1] L.J. Krause, L.D. Jensen, V.L. Chevrier. Measurement of Li-Ion Battery Electrolyte Stability by Electrochemical Calorimetry. J. Electrochem. Soc. 2017, 164 (4), A889-A896.[2] L.J. Krause, L.D. Jensen, J.R. Dahn. Measurement of Parasitic Reactions in Li Ion Cells by Electrochemical Calorimetry. J. Electrochem. Soc. 2012, 159 (7), A937-A943.[3] J.C. Burns, Adil Kassam, N.N. Sinha, L.E. Downie, Lucie Solnickova, B.M. Way, J.R. Dahn. Predicting and Extending the Lifetime of Li-Ion Batteries. J. Electrochem. Soc. 2013, 160, A1451.[4] E. R. Logan, A. J. Louli, Matthew Genovese, Simon Trussler,and J. R. Dahn. Investigating Parasitic Reactions in Anode-Free Li Metal Cells with Isothermal Microcalorimetry. J. Electrochem. Soc. 2021, 168, 060527.