Biodegradable printed paper battery: anode ink mainly made up of zinc and carbon black; cathode ink of manganese or nickel

https://www.ntu.edu.sg/docs/default-source/corporate-ntu/hub-news/ntu-singapore-scientists-develop-biodegradable-printed-paper-batteries.pdf?sfvrsn=9655c66a_1

"battery screen-printed onto both sides of a piece of cellulose paper... reinforced with hydrogel... 4cm x 4cm square of printed paper battery could power a small electric fan for at least 45 minutes... cutting does not affect the functionality... cheaper way of manufacturing batteries... single large piece of battery that can be cut to desired shapes and sizes without loss of efficiency... flexible and wearable electronic systems"