Mass Transport In Solid Oxide Fuel Cell And Lithium Ion Battery

Solid oxide fuel cells?SOFCs?and lithium ion batteries?LIBs?are important energy conversion and energy storage devices,respectively.One of the most important aspects involved in the conversion and storage of energy is the transport of chemical mass.It is important to understand the issues related to the transport of mass in fuel cells and lithium-ion batteries.In solid oxide fuel cells,it mainly involves the conduction of oxygen anions in solid electrolytes and the diffusion of fuel gases in porous electrodes,while the transport in lithium-ion batteries mainly involves the insertion and deintercalation reaction kinetics of Li⁺in solid-state electrodes.By increasing the operating temperature of SOFCs?>800 ^oC?,it is ensured that the oxygen anion has a higher conductivity in the solid electrolyte.However,too high operating temperatures increase the cost of material equipment and reduce the working life,which greatly hinders the development of SOFCs.Recent studies have found that the introduction of interfacial strain is considered to be an effective method to improve the ionic conductivity of SOFC electrolytes and reduce their operating temperature.However,some scattered data can only be obtained through experimental measurements and computer simulations.The quantitative relationship between interface strain and ionic conductivity is still unclear.In this paper,the quantitative relationship between strain and ionic conductivity is established and applied to common ZrO₂ and CeO₂-based electrolytes.The results are basically consistent with the corresponding results.Furthermore,the transport properties of the fuel gas in the porous electrode are related to the microstructure of the porous electrode.Interfacial strain and thermal expansion can affect fuel gas diffusion by altering the microstructure of the nanoelectrodes.In this paper,the quantitative correlation between interface strain/thermal expansion and gas diffusion is proposed.The quantitative effects of strain and thermal expansion on limiting current density and concentration polarization are also analyzed.The influence of neglect strain and thermal expansion on battery performance evaluation is discussed.The chemical diffusion coefficient of Li⁺in the electrode is an important parameter for reacting lithium ion intercalation/deintercalation kinetics and cell rate performance of LIBs.Thus,the measurement of the diffusion coefficient of LIBs is extraordinarily essential.In this paper,a Li⁺diffusion coefficient test method based on dual-cell is proposed according to the Nernst-Eins equation,and the Li⁺diffusion coefficient in the graphite electrode is measured with this method.This method is more efficient and accurate than other methods,and it is capable of measuring the Li⁺diffusion coefficient for the entire charge and discharge process,including the two-phase region and the phase change region.In addition,the method based on the Arrhenius equation can accurately measure the activation energy of Li⁺diffusion in the electrode at different temperatures.