Out‐of‐Cell Oxygen Diffusivity Evaluation in Lithium–Air Batteries

Abstract

AbstractThe diffusion rate of oxygen has a significant impact on the power density, rate capacity, discharge capacity, and electrolyte stability of lithium–air batteries (H.‐G. Jung, J. Hassoun, J.‐B. Park, Y.‐K. Sun, B. Scrosati, Nat. Chem. 2012, 4, 579–585; J. Read, K. Mutolo, M. Ervin, W. Behl, J. Wolfenstine, A. Driedger, D. Foster, J. Electrochem. Soc.­ 2003, 150, A1351–A1356; Y. Cui, Z. Wen, X. Liang, Y. Lu, J. Jin, M. Wu, X. Wu, Energy Environ. Sci.­ 2012, 5, 7893–7897). Oxygen diffusivity in the solid porous cathodes of gas‐based batteries is typically obtained by employing a few electrochemical models. In addition to the indirect computing characteristic, previous methods of evaluating oxygen diffusivity require multiple voltage–current experiments over intact lithium–air batteries, and can cause unnecessary costs resulting from the waste of materials from other battery components (J. Read, J. Electrochem. Soc. 2006, 153, A96–A100). In this report, through derivation and analytical design, a methodology is proposed for the direct out‐of‐cell oxygen diffusivity measurement in lithium–air batteries. The proposed electrochemical devices allow for efficient diffusivity measurements in porous solid cathodes, as well as subsequent quantitative pre‐evaluation of important battery parameters including electrode porosity, thickness, and tortuosity. The proposed methodology is expected to facilitate the development of low‐cost battery systems for a variety of applications, such as large‐capacity automobile batteries and electronics.