Graphite and fiberglass additives for improving high-rate partial-state-of-charge cycle life of valve-regulated lead-acid batteries

Optimization of the cycle life performance of VRLA batteries, working under high rate, partial state of charge (HRPSOC) conditions

“…In the previous work [2] it is clear that passivating lead sulphate films are formed when the battery works continuously under HRPSOC conditions. This sulphate film becomes pro- gressively irreversible, because a dense and thick layer develops as the time under low state of charge conditions increases.…”

“…Results of the previous cycling tests performed in 6 V/20 Ah valve-regulated lead-acid (VRLA) modules, of SPIRAL technology, shows the high power capability of this technology in HRPSOC conditions [2]. Furthermore, the addition of expanded graphite, improves the charge acceptance, and cycle life with respect to other formulations (20-25% compared to standard formulation with carbon black).…”

Understanding the function and performance of carbon-enhanced lead-acid batteries : milestone report for the DOE Energy Storage Systems Program (FY11 Quarter 4: July through September 2011).

“…This theory is supported by Calebeck and Micka, et al 6,7,8 where both titania (TiO 2 ) and alumina (Al 2 O 3 ) were found to provide improvements similar to those obtained by carbon, though their argument was that, in addition to obstructing large pores in the NAM, the additions hindered growth of PbSO 4 crystals, preventing the formation of the large crystallites associated with sulfation. Valenciano, et al 9 also observed a beneficial effect of an inert addition, in their case glass fibers, though the resulting improvement appeared to depend on the manner in which the battery itself was assembled.…”

Review on the research of failure modes and mechanism for lead-acid batteries

“…By using electron probe microanalysis, the maps of PbSO 4 abundance for negative electrodes sampled from selected cells of uncycled and failed battery are presented in Figure 5(a) and 5(b), respectively [78]. The accumulation of PbSO 4 occurs preferentially on the surface region of the electrode, and the top of the electrode registers significantly higher abundance of PbSO 4 than the bottom.…”