Review—Reversible Heat Effects in Cells Relevant for Lithium-Ion Batteries

Abstract

We review measurements of reversible heat effects in lithium-ion batteries, i.e. entropy changes and Seebeck coefficients of cells with relevant electrodes. We show how to compute the Peltier heat of battery electrodes from Seebeck coefficients. The Seebeck coefficient depends on the heat of transfer (Soret effect), which is found from the difference of initial and stationary state values of the Seebeck coefficient. We apply non-equilibrium thermodynamics theory and obtain initial Peltier heats not reported before. For the oxidation of lithium metal we propose the value 34 ± 2 kJ mol −1 when the electrolyte contains 1 M LiPF 6 , while the value is 29 ± 1 kJ mol −1 when the electrolyte contains 1 M LiClO 4 . The positive values imply that the electrode cools when it serves as an anode. For oxidation of lithium under stationary state conditions, the stationary state Peltier heat is ≈120 kJ mol −1 . A large reversible heating effect can then be expected for the single electrode; much larger than expected from the full-cell entropy change. These values have a bearing on thermal modelling of batteries. Peltier heats for anodic reactions are presented in tables available for such modelling. We discuss the need for measurements and point at opportunities.

Thermodynamic and Kinetic Analyses of Ion Intercalation/Deintercalation Using Different Temperatures on NiHCF Electrodes for Battery Electrode Deionization

“…The reason for a larger shift of anodic than cathodic peaks in CVs as temperature increased (Figure ) is due to the reversible heat effects in intercalation battery electrodes which are related to the entropy changes . The temperature dependence of the OCP for each ion in the temperature range of 15 to 75 °C was used to calculate free energy components (entropy and enthalpy) (Figure a).…”

“…32 The reason for a larger shift of anodic than cathodic peaks in CVs as temperature increased (Figure 1) is due to the reversible heat effects in intercalation battery electrodes which are related to the entropy changes. 53 The temperature dependence of the OCP for each ion in the temperature range of 15 to 75 °C was used to calculate free energy components (entropy and enthalpy) (Figure 2a). The increase in temperature resulted in a shift of OCP of all of the four ions to a more negative position, which was consistent with a negative temperature coefficient (ΔE/ΔT) in the literature for a PBA-based electrode.…”

Thermoelectrochemical Seebeck coefficient and viscosity of Co-complex electrolytes rationalized by the Einstein relation, Jones–Dole B coefficient, and quantum-chemical calculations

“…Recently, such an entropy-Se relation was also found to play a crucial role in the thermal modelling of batteries. 45 In 1979, Weaver and co-workers showed that DS rc between the reduced and oxidized forms of transition-metal redox couples (M II/III ) could readily be obtained using non-isothermal electrochemical cells, 46 which formed the basis of TEC. Notably, a much larger DS rc was found for Co II/III compared with those for other transition metals; this observation was explained by the greater metal-ligand bond stretching induced by the (t 2g ) 6 -(t 2g ) 5 (e g ) 2 transition upon the reduction of the Co III species.…”

“…Recently, such an entropy-Se relation was also found to play a crucial role in the thermal modelling of batteries. 45…”

Calorimetry of Capacitive Porous Carbon Electrodes in Aqueous Media

“…Moreover, measurements of the reversible heat give specific information on electrode processes. In the case of batteries, the reversible heat corresponds to T ∆S, where T is the absolute temperature and ∆S is the entropy change, which can also be obtained from the temperature-dependence of the open circuit potential [51,50,102,103,104,105]. In the case of porous capacitive electrodes, the reversible heat of (dis)charging the capacitor informs on changes in the state of the electrical double layer inside the pores.…”