Best materials for Li ion batteries : the chemist's deductive and inductive approach

The performance of lithium ion batteries is essentially governed by the nature of the materials making up their electrodes, positive and negative, hence the constant quest for new compounds. In addition to the conditions required by their crystallographic and band structures, which control their capacity and potential, these materials today must also obey the concepts of sustainable development. These will limit not only the choice of chemical elements making up our electrode materials - iron, manganese and titanium being the most sought-after - but also the processes used to prepare them. Low-temperature syntheses, via hydro/solvo/ionothermal or biomineralization approaches, which are energy-efficient, will be favored. This will be illustrated by two examples involving i) the synthesis of LiFePO4via a biomineralization reaction at room temperature, and ii) the ionothermal synthesis at 250°C of a new family of polyanionic compounds _LiMSO4Ffeaturing attractive electrochemical performances while relying on abundant and inexpensive chemical elements. Current advances in lamellar oxides, including the possibility of using the redox activity of the anionic network in addition to that of the cationic network, will be described. This will highlight the contribution of reasoned theoretical chemistry to the design of new materials.