Pengaruh kadar acetylene black terhadap performa baterai ion litium sel setengah berbasis anoda li4ti5o12 memakai li2co3 sebagai sumber litium dengan proses hidrotermal mekanokimia = Effect of acetylene black content to half cells li ion battery performance based on li4ti5o12 anode using li2co3 as lithium ion source with hydrothermal mechanochemical process