A layered-carbon/PbSO4 composite as a new additive for negative active material of lead-acid batteries

Abstract

We present a layered-carbon/PbSO4 composite additive for the negative active material (NAM) of lead-acid batteries to improve their high rate charge/discharge performance. The layered-carbon/PbSO4 composite, consisting of graphene-like two-dimensional carbon decorated with fine PbSO4 particles, is prepared by a simple chemical vapor deposition (CVD) method and a subsequent ion exchange process. In the synthesis process, potassium carbonate functions as template to promote the generation of layered carbon sheets in CVD process and as template in ion exchange process to in situ produce PbSO4 nanoparticles. The composite can effectively enhance the electronic conductivity and the ionic conductivity of NAM, and resist the tendency to sulfation during high-rate partial-state-of-charge (HRPSoC) operation. Moreover, the PbSO4 deposits on the layered-carbon can not only make the carbonaceous additive be uniformly mixed with the NAM, but also inhibit the hydrogen evolution of the layered-carbon. As a result, the specific capacity, rate performance, and HRPSoC cycling performance of the NAM are significantly enhanced. The NAM with 2 wt% composite additive (the content of layered-carbon in NAM is 0.1 wt%) delivers a high initial specific discharge capacity of 160 mAh g−1 at 0.1 C rate, and 61 mAh g−1 at a high rate of 10 C rate, which is 30% higher than that of the Ref one. The cell with composite additives has achieved a HRPSoC cycle life of 160,000 cycles, which is 3 times longer than the Ref cell.