Review on the roles of carbon materials in lead-carbon batteries

Lead-acid battery (LAB) has been in widespread use for many years due to its mature technology, abound raw materials, low cost, high safety, and high efficiency of recycling. However, the irreversible sulfation in the negative electrode becomes one of the key issues for its further development and application. Lead-carbon battery (LCB) is evolved from LAB by adding different kinds of carbon materials in the negative electrode, and it has effectively suppressed the problem of negative irreversible sulfation of traditional LAB. Different carbon materials play different roles in LCB, including construction of conductive network, double-layer capacitance storage effect, formation of porous structure and steric effect. Moreover, research on composite material additives (such as Pb-C composite materials and polymer-C composite materials) and Pb-C composite electrode have become a research focus in the past few years; it has been another effective way to improve the performance of the negative electrode. On the other hand, due to the relatively low overpotential of carbon materials, the hydrogen evolution reaction (HER) will be aggravated in LCB, which affects its electrochemical performance. It is necessary to modify carbon additives or add other additives to inhibit the HER. This paper will attempt to summarize the roles of carbon additives in the negative electrode made by previous research and illustrate the effect of composite material additives and Pb-C composite electrode on the negative electrode. Moreover, we will also sum up the method for solving the HER by reviewing previous research.