Batteries have always been a highly sought-after application for graphene materials, bearing promises of expanded capacity, ultra-fast charging, improved safety of use and more.
Early testing in labs and research institutes were very promising, but the move from lab to market proved more challenging than people expected. Even today, in 2021, graphene batteries aren't on the market yet, in any major way.
We do see, however, some niche adoption - for example, the use of graphene to enable novel battery casings, or extending the battery's temperature range (see Huawei's 2016 graphene battery announcement for example). But actual graphene-enhanced battery anodes or other components haven't been realized yet.