Simulations are developed to explore the first discharge of a lithium-air battery. Constructed on the basis of porous-electrode theory [1].A main challenge confronted in lithium-air battery modeling is that insoluble discharge products deposit onto pore walls within the porous cathode, causing its microstructure to change during discharge [2]. Discharge-product growth shrinks (or even blocks) pores, decreases the surface area available for charge transfer, and leads to interfacial resistances to charge and material exchange. Our model takes into account these effects of discharge-product growth. The inclusion of pore-size and surface-to-volume variation with local charge state enables studies of morphology evolution within the porous cathode; treating the discharge-product phase explicitly within the model allows various transport mechanisms within the discharge product to be explored [3]. Figure 1. <img src='https://acs-archive-assets2.s3.amazonaws.com/239nm/uploads/14435_alkene_diboration.jpg' alt='' />Fig. 1 presents typical model output, showing the evolving reaction distribution in the porous cathode. As time passes, the reaction zone moves toward one edge of the cathode, rather than being evenly distributed throughout. This indicates that only part of the cathode is in use, limiting its capacity. Our talk will discuss a variety of factors that limit cell capacity, and provide design criteria that ensure complete cathode utilization.[1] J. Newman and K. Thomas-Alyea, Electrochemical Systems, 3rd Ed., 2004, Wiley.[2] G. Girishkumar, et al., J. Phys. Chem. Lett. 1 (2010) 2193-2203[3] P. Albertus et al., J. Electrochem. Soc. 158 (2011) A343-A351

Continuum-scale modeling of lithium-air batteries

246th National Meeting (2013)

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