Positive thin electrodes obtained from hydrothermally synthesized 4BS for lead-acid batteries

Tetrabasic lead sulfate, 4 PbO·PbSO4 (4BS), was prepared from an aqueous suspension of leady oxide by using a simple hydrothermal method. Digesting the paste at a moderate temperature (125 °C) and heating for a short time (30 min) ensured the obtainment of particles of small, uniform size. The material was deposited on a lead alloy substrate 0.2 mm thick by spraying from aqueous suspensions. The deposits were highly uniform and homogeneous, with a coating thickness of 100 μm. A multi-step charge algorithm involving no preliminary soaking provided the best 4BS → PbO2 conversion. The resulting electrodes delivered a capacity of 115 Ah kg−1 with excellent capacity retention over more than 500 cycles at 100% depth of discharge (DOD).