Upcycling spent lead-acid battery paste: nanostructured leady oxides from metal-organic frameworks

A green hydrometallurgical process for the recycling of lead-acid battery paste has been developed. The technology uses chelating organic acids to capture lead in the form of a metal-organic framework (MOF). The intermediate MOF is converted into highly advanced, nanostructured, battery-grade oxides which exhibit enhanced energy and power densities, among other properties. In a recent 3rd party-trial, it has been shown that energy densities can increase by as much as 40% - this is due to the high surface area of the oxides made by the process.

By controlling the conditions, we have been able to convert the MOF into battery alpha oxide; beta oxide; and controlled mixtures of alpha and beta. Moreover, it is possible to produce red lead or lead sesquioxide as the final product. This level of control could enable fine-tuning of battery plate for specific applications (e.g. more power in automotive batteries, more cycling for stationary batteries and renewable energy storage, etc). Meanwhile, the quantity of lead in these leady oxides can be controlled to anything from negligible (less than 1% lead) to greater than 20%.

The wet chemistry has been scaled up to 5 tonnes per hour continuous treatment of spent paste (modular), while the life-cycle analysis shows potential for reducing the carbon footprint of traditional recycling by approximately 85% and waste by more than 90%. The process saves considerable energy by not relying on a traditional furnace or electro-process – saving the equivalent of at least 3,000 tonnes of coal per 10,000 tonnes of batteries processed.