[en] This report first proposes an overview of the situation and perspectives of the world market of batteries by addressing strategic stakes of this market (the development of electro-mobility as the true engine of the market, the still emerging market of stationary storage, and the market perspectives by 2030. Then, it discusses the stakes of battery technology by presenting this technology (main technological families, basic components, operation principle, performance criteria), by focussing on the different and competing lithium-ion technologies, and on research orientations for the battery of the future. It reports an analysis of the sector at the world level by presenting some basic aspects (6 steps for the sector, battery at the heart of mineral geopolitics, reuse and recycling), by presenting Asia as the pillar of the world industry of batteries, and by proposing a focus of development projects of 5 world leaders (CATL, BYD, LG Chem, Panasonic, and a non-Asian leader, Tesla). The second part presents the European Alliance of batteries with its institutional framework and its genesis, its available financial instruments, and its challenges on the short and medium terms. It focusses on mega-factories which are competing to conquest Europe: main mega-factories projected in Europe, case of Northvolt (a European Tesla), rationale of foreign investments in EU mega-factories. It finally proposes an overview of the industrial strategies of actors involved in the Important Projects of Common European Interest (IPCEI)