AGM --- high surface-area

As a result of such considerations, the surface area, particularly fine-fibre content of AGM separators has been the subject of two ALABC projects on EV batteries. In the first project [16], acid stratification was found to decrease as the surface area of the separator was increased, see Table 7.5. Nevertheless, any advantage in terms of battery cycle-life was less clear-cut, see Table 7.6. 

Post-service examination revealed that all positive plates had undergone softening and considerable expansion. In addition, lead dioxide particles had penetrated the separator. The general condition of the positive plates was better with separators of higher fine-fibre content, which was related to the lower degree of acid stratification. 

figures in brackets represent percentage of initial thickness at 10 kPa. 

Cycles at end-of-service Specific surface-area (m g- ) Fine-fibre content (%) Acid densities regions (gcm in different separator  

Specific surface-area Fine-fibre content (%) Cell pressure (kPa) Cycles when capacity loss first reaches 20% Cell pressure at initial cycles (kPa) 

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