Predicting the cost of a 24 V soluble lead flow battery optimised for PV applications

Providing reliable electricity from small-scale renewable power is an important challenge for emerging economies. The soluble lead flow battery (SLFB) is a promising battery for this application, as it has a simple architecture making it relatively robust, and a lifetime of 2000 cycles demonstrated at the cell level. Also, the electrolyte is manufacturable directly from spent lead acid batteries. There is a need for techno-economic models to allow the cost/performance of a complete system to be defined and optimised. Such a model is defined here for the first time and used in a multi-objective optimisation to design a 24 V system for a charging hub in Sierra Leone. A 4 h duration was found to be optimal, and electrolyte for a 3.5 kW/14 kWh system would fit in a 1000 L IBC. Methanesulfonic acid was found to be the largest cost component of the 4 h system, with graphitic bipolar plates next. Both have low raw material costs, and in an optimistic scenario a total component cost of <£50/kWh would be achieved, half that of current NMC Li-ion cells. The greatest technical risk to achieving low cost is deposit thickness of lead dioxide. This important research gap should be addressed.