The article presents the recent progress in the carbon honeycomb grid technology for valve-regulated
lead-acid batteries with absorptive glass-mat separators (AGM-VRLAB). The work is focused on the
development of negative current collectors using industrial grade composite honeycomb precursors. The
developed model AGM-VRLA cells comprised of one prototype honeycomb negative electrode and two
conventional traction positive counter-electrodes show high utilisation of the negative active material
and long cycle life both in high-rate partial state of charge (HRPSoC) cycling mode and in deep cycling
mode. The analysis of the results from the cycle-life tests and the tear-down analysis indicate that the
benefits delivered by the novel grids can be related to the low mesh size of the grid, lowg-coefficient, as
well as the use of milled carbonfibre additive. The combination of the three, results in the reversibility of
the negative active material sulfation process when the electrolyte concentration in the cells is lower
than the one traditionally used in the AGM-VRLAB technology. The negative plates show no signs of
irreversible degradation after more than 900 cycles in deep cycling mode and more than 2000 capacity
turnovers (equivalent cycles) in HRPSoC cycling mod