A group of scientists based in Korea, Germany and Poland (CMPW PAN) have developed a lithium ion battery in which highly crystalline graphene coats silicon cathode material. Using this material leads to batteries with energy densities two times more than commonly-used lithium ion batteries. The study has been published in the online journal Nature Communications published as "Silicon carbide-free graphene growth on silicon for lithium-ion battery with high volumetric energy density".

http://www.nature.com/ncomms/2015/150625/ncomms8393/full/ncomms8393.html
http://physicsworld.com/cws/article/news/2015/jul/06/graphene-coating-boosts-battery-performance