Three-dimensional (3-D) insertion compounds for batteries : structure-electrochemistry relationships and shaping

Thanks to its high energy density and attractive cost-performance ratio, Li-ion technology is emerging as the electrochemical system of choice for electric mobility and grid applications, with market projections that are quite staggering (>3000 GWh in 2030). This will not be without raising questions about the abundance of materials, recycling and the design of more eco-compatible electrode materials, while preserving or even increasing their energy density. These positive electrode materials, based on insertion reactions, can still be perfected. The 2022 lectures were limited to lamellar insertion materials, oxides or sulfides, capable of inserting ^Li+ or ^Na+ ions. Thus, the Li(_{Ni1-x-yMnxCoy})_O2 lamellar phases, also referred to as (NMC) at the origin of the most efficient Li-ion batteries (250 Wh/kg, 700 Wh/l) and which today power electric vehicles, were introduced. However, the current economic climate has made less efficient but more eco-compatible materials with three-dimensional structures, such as _LiFePO4, more attractive, and they could dethrone NMCs for low-end or heavy-duty vehicles (trucks and buses). This year's lecture will therefore be dedicated to the families of 3-D electrode materials and will follow the historical development of their discoveries. In each case, the effect of elaboration process, phase stoichiometry and structure on the material's electrochemical properties will be presented. Li[Mn(Ni)]_2O4 spinel compounds will be discussed first. These will be followed by so-called "polyanionic" compounds of the _AMXO4 type based on phosphate, borate, silicate and sulfate polyanions. Na-based 3-D insertion compounds will be discussed in conclusion. These lectures will be followed by seminars dedicated to recycling (P. Barboux), the intercalation chemistry of fluorinated compounds or mixed anions (V. Maisonneuve and C. Tassel) and the synthesis and development of new 3-D materials for optical or electronic applications (S. Jobic and M. Hayward) respectively. Organic materials as an alternative to inorganic compounds (P. Poizot) will close this series of seminars.