The increasing demand for smart portable electronics and electric vehicles is driving advancements in high-energy-density lithium-ion batteries (LIBs). Among various cathode materials, lithium manganese iron phosphate (LiMn_yFe_1−yPO₄ – LMFP) stands out due to its cost-effectiveness, excellent safety profile, long cycle life, high operating voltage, robust thermal stability, and competitive energy density. However, despite notable progress, LMFP still encounters key challenges such as limited electronic conductivity, sluggish Li-ion diffusion, manganese dissolution affecting cycling stability, and low tap density. To address these issues, significant efforts have been devoted to developing multimetal LMFP and other multimetal olivine-based cathodes with enhanced electrochemical properties. Nevertheless, a comprehensive review of these recent advancements remains lacking. This article aims to bridge this gap by examining emerging strategies and recent developments in multimetal LMFP cathodes for LIBs. It systematically compares various optimization approaches, including (i) doping with single or multiple elements at Li-, M-, or Li & M-sites, (ii) integrating additional primary constituents or structural components, and (iii) increasing the configurational entropy of electrode materials. The advantages and limitations of these strategies are critically assessed. Furthermore, key synthesis methodologies and processing techniques used to enhance LMFP cathode performance are discussed. Finally, the review provides insights into the benefits and challenges associated with these materials, highlighting future perspectives and potential research directions.

Flavylium cations serve as models for the chemical and photochemical reactivity of anthocyanins, the natural plant pigment responsible for many of the red, blue and purple colors of fruits and flowers. Likewise, pyranoflavylium cations serve as models of the fundamental chromophoric moiety of pyranoanthocyanins, molecules that can form from reactions of grape anthocyanins in red wines during their maturation. In the present work, hybrid pigments are prepared by the adsorption of a series of five synthetic flavylium cations (FL) and five synthetic pyranoflavylium cations (PFL) on sepiolite clay (SEP). The FL are smaller in size than the PFL, but both can in principle fit into the tunnels and/or external grooves (with dimensions of 3.7 × 10.6 Å) of SEP. Measurements of the fluorescence quantum yields of the adsorbed dyes indicate that they are at least as fluorescent as in acidic acetonitrile solution, and in a few cases substantially more fluorescent. The observation of biexponential fluorescence decays is consistent with emission from dye molecules adsorbed at two distinct sites, presumably tunnels and grooves. These hybrid materials also have improved properties in terms of stability of the color in contact with pH 10 aqueous solution and resistance to thermal degradation of the dye. SEP thus appears to be a promising substrate for the development of highly fluorescent flavylium or pyranoflavylium cation-derived hybrid pigments with improved color and thermal stability.

An improved procedure is described for the preparation of pyranoflavylium cations from the reaction of 5,7-dihydroxy-4-methylflavylium cation with aromatic aldehydes. Modifications of the procedure of Chassaing et al. (Tetrahedron Lett. 2008, 49, 6999–7004; Tetrahedron 2015, 71, 3066–3078) circumvent the reported restriction to electron-rich benzaldehydes and provide access to a wide variety of substituted pyranoflavylium cations, including those with electron-withdrawing substituents or an attached heterocyclic or polycyclic aromatic ring. This opens the way for studies of substituent and structural effects on the ground and excited states of these pyranoanthocyanin analogues, the behavior of which should mirror fundamental aspects of the chemistry and photophysics of the pyranoanthocyanin chromophores present in mature red wines.