Abstract—A computational fluid dynamics (CFD) model is developed for rechargeable non-aqueous electrolyte lithium-air batteries with a partial opening for oxygen supply to the cathode. Multi-phase transport phenomena occurred in the battery are considered, including dissolved lithium ions and oxygen gas in the liquid electrolyte, solid-phase electron transfer in the porous functional materials and liquid-phase charge transport in the electrolyte. These transport processes are coupled with the electrochemical reactions at the active surfaces, and effects of discharge reaction-generated solid Li 2 O 2 on the transport properties and the electrochemical reaction rate are evaluated and implemented in the model. The predicted results are discussed and analyzed in terms of the spatial and transient distribution of various parameters, such as local oxygen concentration, reaction rate, variable solid Li 2 O 2 volume fraction and porosity, as well as the effective diffusion coefficients. It is found that the effect of the solid Li 2 O 2 product deposited at the solid active surfaces is significant on the transport phenomena and the overall battery performance. Keywords—Computational Fluid Dynamics (CFD), Modeling, Multi-phase, Transport Phenomena, Lithium-air battery. I. INTRODUCTION ITHIUM (Li) battery has attracted much more attention worldwide during the last years as a possible solution for various applications, particularly for electric vehicle (EV) propulsion applications. The present Li-ion battery performance is too low [1]-[3], and increasing research activities have been focused on the ones beyond the Li-ion battery, such as Li-air battery. The Li-air battery comprises of lithium metal anode working as a lithium source supplier, carbon based cathode (with/without catalysts), as well as a separator between them. The fundamental discharge chemistry in Li-air batteries is electrochemical oxidation of lithium metal at the anode and reduction of oxygen from air at the cathode [2]. The generated lithium ions in the anode moves through electrolyte and meet with oxygen obtained from air at the cathode and forms lithium oxide which is accumulated on the porous particles (usually carbon). The Li-air battery cathode microstructure is basically the same as that in PEMFC cathodes, but it usually flooded with liquid electrolytes and Jinliang Yuan is with the Department of Energy Sciences, Faculty of Engineering, Lund University, Box 118, 22100 Lund, Sweden (phone: +46 46 222 8413, e-mail: Jinliang.yuan @energy.lth.se). Jong-Sung Yu works at the Department of Advanced Materials Chemistry, Korea University, 2511 Sejong-ro, Sejong, 339-700, Korea. Bengt Sundén is with the Department of Energy Sciences, Faculty of Engineering, Lund University, Box 118, 22100 Lund, Sweden. should be dehydrated because lithium metal is very sensitive to moisture and aggressively reacts with water [4]. So the Li-air battery is an emerging type of energy storage and conversion device which may be considered as half a battery and half a PEMFC [5]. In non-aqueous Li-air batteries, insoluble lithium peroxide Li 2 O 2 (1) and potentially lithium oxide Li 2 O (2) are formed in ORR (oxygen reduction reaction) during discharging. With catalysts present, Li 2 O 2 might undergo the OER (oxygen evolution reaction) when sufficient high recharge voltages are applied in recharging process. The reactions occur at three-phase boundaries (TPB) involving the solid electrode (for electrons), liquid electrolyte (for Li + ) and dissolved oxygen gas (O 2 ) in the electrolyte. 2Li + +2e - + O 2 ↔ (Li 2 O 2 ) s E rev = 2.96 V (1) 4Li + +4e - +O 2 ↔ 2(Li 2 O) s E rev = 2.91 V (2) where E rev is the reversible cell voltage, referenced vs Li/Li + in this study. The forward reaction in (1) refers to the discharging while the reverse direction stands for the charging process. It is found that Li2O2 is the dominant reaction product in the most recent Li-air battery tests. Along with experimental studies carried out for different physicochemical properties and the overall performance, theoretical analysis of the electrode structure/morphology and transport phenomena affected by the reaction products is becoming important for achieving high-capacity non-aqueous Li-air batteries. The modeling studies at continuum scale (such as CFD at the battery level) may account for the microscopic material, chemical and morphological properties, which can be a great help to understand the coupled transport phenomena and reactions within the battery for improving its design and optimizing the performance, as well as for identifying their effects on the “sudden death” (i.e., over-potential sharp increase or voltage sharp decrease), and the degradation/failure mechanisms, etc. The macroscopic or the continuum scale models consider the porous structure as a black box or as a macro-homogeneous porous region (uniformly distributed solid spheres or agglomerates). With suitable boundary conditions specified, a set of governing differential conservation equations for the transport processes can be discretized using conventional CFD techniques, such as finite volume method (FVM), as applied for proton exchange membrane fuel cells [6]. These methods CFD Analysis of Multi-Phase Reacting Transport Phenomena in Discharge Process of Non-Aqueous Lithium-Air Battery Jinliang Yuan, Jong-Sung Yu, Bengt Sundén L World Academy of Science, Engineering and Technology International Journal of Materials and Metallurgical Engineering Vol:9, No:3, 2015 283 International Scholarly and Scientific Research & Innovation 9(3) 2015 scholar.waset.org/1307-6892/10000680 International Science Index, Materials and Metallurgical Engineering Vol:9, No:3, 2015 waset.org/Publication/10000680