Reconstruction of Lead Acid Battery Negative Electrodes after Hard Sulfation Using Controlled Chelation Chemistry

Abstract

Lead acid batteries (LABs) remain an inexpensive energy storage technology with a wide application base. However, their short cycle lifetimes necessitate improved recycling and maintenance technologies to combat their various failure modes. One major cause of failure is hard sulfation, where the formation of large PbSO 4 crystals on the negative active material impedes electron transfer. Here, we introduce a protocol to remove hard sulfate deposits on the negative electrode while maintaining their electrochemical viability for subsequent electrodeposition into active Pb. Soaking the hard sulfate negative electrode in an alkaline EDTA solution reshaped the surface by solubilizing PbSO 4 to Pb-EDTA while avoiding underlying Pb phases. Thereafter, we explored electrodeposition of the Pb-EDTA complex as fresh electrode material and found reduction of Pb-EDTA required lower deposition overpotentials with decreasing pH. We used electrodeposited films on gold to demonstrate cycling of the restored active Pb in H 2 SO 4 . The film's capacity gradually faded with cycling and PbSO 4 formation, alike to commercial LABs. Lastly, we demonstrated the electrodeposition of Pb directly onto negative electrodes from a commercial LAB. Our unique approach seeds opportunity for recycling the electrode materials inside LABs without disassembly or extensive material processing.

In situ detection of reactive oxygen species spontaneously generated on lead acid battery anodes: a pathway for degradation and self-discharge at open circuit

“…Better performing LABs with longer cycle life can have implications in lead waste reduction. 11,15,63 However, our results and methodology are not only applicable to LABs. Monitoring ORR-related processes at air-metal batteries is crucial to understand the formation of reactive species that cause interfacial passivation due to interactions with organic components.…”

“…[8][9][10] On the other hand, sustainable refurbishing LABs eliminates disassembly/reassembly processes and could minimize the latter issues. 11 Thus, understanding the sources of electrode passivation and materials degradation becomes critical in determining refurbishment strategies.…”