The efficiency encompasses for example the charging efficiency and the self-discharge rate, durability includes cycle-life, shelf-life, and robustness against misuse. Among them, battery storage systems are popular and are found with a wide range of chemistries. Due to these different chemistries, the efficiency, durability, bulkiness and cost of batteries vary a lot. Batteries can be further categorised in normal (atmospheric temperature) batteries, e.g. lead-acid (Pb-acid), lithium-ion (Li-ion), nickel metal hydride (NiMH), high temperature batteries, e.g. Na-NiCl2 or NaS, and flow batteries, e.g. polysulfurs sodium bromide (PSB), vanadium redox battery (VRB), or zinc-brome (ZnBr).