During the last twenty-five years Lithium Ion Batteries (LIBs) have expanded their landscape in large-scale applications and are now well positioned to achieve the Electrical Vehicle (EV) horizon, thus lessening our dependence towards fossil fuels. Among all possible negative electrode materials used in commercial LIBs, graphite is the most employed due to its lowest operating potential and to its excellent cyclability. However, such an operating potential (~ 0.1 V vs. Li⁺/Li) induces considerable risk of decomposition associated with lithium dendrite growth. Coupling many advantages in one material, conjugated lithium carboxylates can be seen as one of the best alternative to overcome these issues and thus became serious candidates to supplant LTO in the future. However, employment of organic material remains at an early stage compared with classical anode materials. A step forward deep structure-property relationship has clearly to be performed to reach the target of sustainable energy storage. The main difficulty of such approach nests in the combination of different fields, e.g. organic synthesis, material science and solid-state electrochemistry, all of them having an impact on the performances (e.g.material particle size on activity/conductivity or electrolyte on capacity. Nevertheless, electrochemical activity remains primarily governed by the molecular structure which is the starting point of the electrode material conception. As an example of the importance of molecular design on electrode performances, we first studied the impact on the rate capability of the stabilization center using naphthalene (Fédèle et al., JES, 2014) and perylene Fédèle et al., J. Mat. Chem. A, 2014) cores and very recently the incidence of the conjugation distance between two carboxylates using a layered material based on a 4,4’-biphenyl unit (Fédèle et al., Chem. Mater., accepted).

In order to explore in details the impact of the delocalization extent on electrochemical performances of conjugated dilithium carboxylate, we focused on substituted or bridged biphenyl-based materials using a coupled theoretical/experimental approach. Thanks to these investigations, we clearly showed a dramatic influence of key structural parameters modulating (or tuning) the electron movement ability and define new trends to control the redox potential, reversibility and rate capability by adding selectively atoms on the aromatic backbone. This work thus opens new perspectives towards the understanding of the reactivity of such family.