Limited safety, sustainability and recyclability are key drawbacks of today’s lithium-ion battery technology, along with restricted availability of starting materials (e.g. cobalt). In the search for alternative electrochemical energy storage systems for use in e-mobility and for storing energy from renewable sources, a combination of battery and capacitor is very promising: the “hybrid supercapacitor.” It can be charged and discharged as quickly as a capacitor and can store almost as much energy as conventional batteries. In comparison to the latter, it can be charged and discharged much faster and much more frequently: while a lithium-ion battery achieves a service life of a few thousand cycles, a supercapacitor manages around one million charging cycles.
System made of carbon and salt water
A particularly sustainable, but so far quite unexplored variant of such a hybrid supercapacitor consists of carbon and aqueous sodium iodide (NaI) electrolyte, with a positive battery electrode and a