1, Vanderbilt University, Nashville, Tennessee, United States
With the development of electric vehicles on the rise, what will be the fate of the over 250 million combustion engine vehicles in the United States? Recycling the elemental lead from the lead-acid batteries in our vehicles for use in low cost sodium-lead batteries may be a promising route for large scale energy storage. Additionally, the infrastrucutre for recycling these batteries is already in place, with over 95% of lead-acid battery waste currently being recycled. Previous sodium-lead anode chemistries have shown high volumetric energy densities at the cost of poor cycling performance due to the high volumetric expansion associated with sodium lead alloying. This work highlights the use of diethylene glycol dimethyl ether (diglyme) as an electrolyte solvent to improve the cyclic stability of sodium-lead alloying at the anode. Diglyme molecules are hypothesized to form weak coordinations with sodium cations, and these freely moving complexes enhance the diffusion of sodium through the SEI layer without damaging the layer, which preserves its protective properties throughout cycling. This novel chemistry allows the fabrication of sodium-lead batteries with high capacity per unit volume, while retaining the capacity through hundreds of cycles. Relative to its lithium-ion counterparts, the abundance and cost of the raw materials for this device are the highlights of its potential impact on the future of energy storage. If the lead-acid battery from every vehicle in the United States were recycled, the resulting quantity of sodium-lead grid energy storage would exceed 700 GW, which would enable the storage of 70% of the nation's current energy production (~1000 GW).