Abstract: This work creates a droplet battery model based on the electrolyte performance in the porous electrode, studies the current density on the mesoscopic scale, and explains how the mesoscopic structure of the porous electrode influences the current density on the air-diffusion electrode. Near the three-phase line, there is a strong band containing nearly 80% current. For porous electrodes, the total current is proportional to
the length of the strong band. Thus, it can be inferred that on the macroscopic scale, the longer the total length of the strong band on unit area is, the larger the current density is.

Key words: damage identification, parameter identification, online identification technique, health monitoring technique, droplet battery, mesoscopic computation, metal/air battery, strong band, air-diffusion electrode, three-phase line