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Reversible heat generation rates of blended insertion electrodes

: Heubner, Christian; Schneider, Michael; Michaelis, Alexander


Journal of solid state electrochemistry 21 (2017), Nr.7, S.2109-2115
ISSN: 1432-8488
ISSN: 1433-0768
Fraunhofer IKTS ()
reversible heat; blended electrodes; insertion; battery

The blending of lithium ion insertion compounds is a novel and promising approach to design advanced electrodes for future secondary batteries. Recently, considerable improvements regarding power density and safety issues have been achieved by combining several insertion compounds. However, the understanding of basic interactions between the constituents of the blend is still ongoing. In the present theoretical study, we derive a mathematical model of the reversible heat generation rate of a blended insertion electrode based on the thermodynamic properties of its constituents. The reversible heat is found to be a function of the entropy of the lithium insertion reaction, the mass fraction, and the differential capacity of each constituent in the blend. The impact and the significance of these parameters on the reversible heat generation rate and its state of charge dependence are analyzed. The derived relations can be used to determine the reversible heat profile of a blended insertion electrode for all possible compositions if the properties of the pure constituents are known. The results suggest the opportunity of designing specific reversible heat profiles by a targeted compilation of the blend.