Usually the potentials of Li-ion battery electrodes (at constant temperature) are expressed against metallic lithium, assuming that it equals zero. In the case of potential temperature coefficients, and hence entropies, no similar assumption can be applied, as it is against the third principle of thermodynamics. Here, single electrode potential temperature coefficients were estimated using a ‘negligible thermal diffusion potential assumption’. The open circuit voltage (Δϕ_i) dependence on temperature T, for three Li-ion battery cathodes, was measured in non-isothermal symmetrical cells (both electrodes had the same composition but were kept in different temperatures). The measured values were interpreted as single cathode (LiMn₂O₄, LiFePO₄ and LiCoO₂) potential temperature coefficients dϕ_i/dT, assuming that Soret and Thomson effects are negligible. The single cathode potential temperature coefficients, estimated in such a way, were positive (dϕ(LiMn₂O₄)/dT = 0.86 mV K⁻¹, dϕ(LiFePO₄)/dT = 0.86 mV K⁻¹ and dϕ(LiCoO₂)/dT = 0.83 mV K⁻¹). In addition to the measurements in non-isothermal cells, the temperature coefficients of the open circuit voltage of isothermal cells consisting of these cathodes and a metallic lithium reference (dE/dT) were determined. In this case, all temperature coefficients of the cell voltage were negative (dE(Li|LiMn₂O₄)/dT = −0.20 mV K⁻¹, dE(Li|LiFePO₄)/dT = −0.08 mV K⁻¹ and dE(Li|LiCoO₂)/dT = −0.25 mV K⁻¹). The temperature coefficient of the single metallic-lithium electrode, dϕ_Li/dT, was calculated from the temperature coefficients dE/dT of isothermal cells consisting of the cathodes and a lithium counter-electrode and the dϕ_i/dT values measured in non-isothermal cells: dE/dT = dϕ_i/dT − dϕ_Li/dT. The dϕ_Li/dT value was 1.03 mV K⁻¹. The measured difference in the dϕ/dT values for metallic lithium and graphite (LiC₆) anodes was small (dE/dT = dϕ(C₆Li)/dT − dϕ_Li/dT = −0.08 mV K⁻¹). Literature data on the temperature coefficients of the isothermal cell open circuit voltage containing different electrodes at different states of charge (SOC) and metallic-lithium counter electrodes were used for the calculation of single electrode properties, taking into account that dϕ_Li/dT = 1.03 mV K⁻¹. The temperature coefficients of all single electrodes were positive for different SOC values and ranged between 1.69 mV K⁻¹ and 0.84 mV K⁻¹. The values of entropy change, ΔS_i, for reversible single electrode reactions were all positive (for different states of charge) and ranged between ca. 70 J mol⁻¹ K⁻¹ and 120 J mol⁻¹ K⁻¹.

A sustainable electrode architecture combining MoS ₂ , SnS, or Sb ₂ S ₃ with a polypyrrole–carbon black (PPyCB) network and locust bean gum (LBG) binder improves sodium-ion battery performance and structural stability.

Eight commercial 10F electrochemical double-layer capacitors (EDLCs) were connected together and placed in a container filled with mineral oil. The whole system was placed into a Dewar container. Temperature variation and heat exchanged between the test EDLC and the environment during its charging, discharging, and “self-discharge” were measured, together with voltage U changes. Charge separation during charging was equivalent to a transition into a more ordered system, which results in entropy decrease, while discharging caused entropy increase (the Peltier–Seebeck effect). Consequently, a number of charging/discharging cycles led to a corresponding series of entropy and temperature changes. The final shape of temperature versus time curve during charging/discharging cycles was due to overlapping of irreversible Joule–Lenz and reversible Peltier heats. When charged EDLC was kept under the open-circuit condition, measured heat flow was negligible in comparison to energy loss calculated from potential drop, assuming that energy E accumulated is proportional at any time to voltage to the second power (i.e., E ~ U ²). The result was interpreted assuming that the EDLC “self-discharge” phenomenon is not associated with energy loss by the device, but rather with charge redistribution between EDLC particles characterized by different time constants.

This work investigated the impact of temperature on the diffusion of lithium ions within cells. To achieve this, electrochemical impedance spectroscopy (EIS) analysis was conducted at various temperatures across three distinct cells. These cells utilized an electrode composed of corn starch meringue and were paired with three different electrolytes. Notably, one electrolyte included an additional 5% of starch. The objective of this study extends beyond merely determining resistance from graphical representations; it also entails performing a kinetic analysis of specific systems, with a particular emphasis on elucidating the significance of the lithium-ion diffusion coefficient as a critical parameter. The cell with 1 M LiPF₆ in the EC/DMC/DEC electrolyte and corn starch-based electrode exhibited the most horizontally oriented Warburg curve, representing the smallest angle.

This study presents a novel approach to the use of kraft lignin in electrochemical energy sources, with a focus on its use as anode material. The key novelty of this study is the use of natural casein as an innovative binder in electrode production, offering a sustainable and efficient alternative to conventional binders. The carbonaceous material was obtained from kraft lignin by two heat treatments at a relatively low temperature of 300 °C—one in a nitrogen atmosphere and the other in air. The results indicate that carbonization at this lower temperature provides promising electrochemical properties while improving cost-effectiveness and energy efficiency compared to higher temperature processes. Additionally, wettability analysis based on contact-angle measurements revealed substantially improved electrolyte affinity for casein-based electrodes, which correlates with their enhanced electrochemical performance. The study showed promising performance of the developed electrodes as follows: a capacity of 67 F g⁻¹ for supercapacitor applications, 250 mAh g⁻¹ for lithium-ion batteries, and 50 mAh g⁻¹ for sodium-ion batteries. These results confirm that kraft lignin, in combination with casein as a binder, is an environmentally friendly and economically viable alternative to traditional electrode materials.