The Effect of the Structure of a Positive Electrode on the Process of Discharge of a Lithium–Oxygen Power Source. The Monoporous Cathode Theory

Abstract

The results of computerized simulation of the process of formation of lithium peroxide attending the discharge of lithium–oxygen power source, in individual pore of constant radius are presented. It is found that, in the model of porous cathode (pores are tortuous, noncrossing, and of the same radius), variation of specific surface of the pores (decrease of pore radius) does not enable a possibility to increase notably the value of specific capacity of the cathode. A necessity of presence of both macropores, and micro- and mesopores in the structure of the active material was discussed. The effect of porous structure of the cathode on the discharge characteristics of LOPS was experimentally demonstrated by the example of some cathode materials (carbon blacks and carbon nanotubes). The highest discharge capacity was achieved with use of the sample of CNT-TNaOH combining pores of various sizes, which corresponds to the formulated hypotheses about an optimal structure of the active cathode material.