The sustainability of lead-acid batteries, in any application, will always beat Li-Ion due to their unique ability of being fully recyclable. The process that the battery goes through whilst being recycled means that we can get each and every component back from the old battery and can be used to make a new lead-acid battery.  

Lead-acid batteries are sustainable due to their closed-loop life cycle, which refers to the process of collecting the waste, putting it into the reserve, the battery-box crushing pre-treatment and the storing and reuse of the products obtained in a new production cycle. Lead-acid batteries also reduce greenhouse gas emissions in vehicles, which reduces global warming, as well as cutting fuel consumption by up to 10%. 

They are also 100% recyclable, with more than 98% of lead-acid batteries recycled, compared to the 97% of lithium batteries that are not recycled, and they have a long-lasting life, meaning that less have to be used. 

The recycling of lead-acid batteries does not harm the environment, in fact it helps to support agricultural needs and enhance energy conservation as they are vital components of off-grid systems for electric power generation based on renewable sources. This means that lead-acid batteries can make an important impact to enhancing the use of renewable energy resources and to reducing or avoiding the use of fossil fuels in electric power generation.