Lithium and cobalt are fundamental components of lithium-ion batteries. Analysis by researchers at the Helmholtz Institute Ulm (HIU) of the Karlsruhe Institute of Technology (KIT) shows that the availability of both elements could become seriously critical. Cobalt-free battery technologies, including post-lithium technologies based on non-critical elements such as sodium, but also magnesium, zinc, calcium and aluminium, represent possibilities to avoid this outcome in the long term. These results are presented in Nature Reviews Materials.