What "green batteries" are currently in use and under research?

New - type green and environment - friendly batteries refer to a kind of batteries with excellent performance and no pollution that have been put into use in recent years or are under development. Currently, a large number of lithium - ion batteries and nickel - metal hydride batteries that are in use, mercury - free alkaline zinc - manganese batteries that are being promoted, as well as lithium or lithium - ion plastic batteries, fuel cells, and electrochemical energy - storage supercapacitors that are under research and development all fall into the category of new - type green and environment - friendly batteries. In addition, solar cells, which are widely used to convert solar energy into electricity, also belong to this category.