Abstract
Promoting the emergence of efficient organic Li-ion batteries requires notably air-stable lithiated organic structures able to reversibly deintercalate Li at high enough potential values. To date, most of cathode materials reported in the literature are typically synthesized in their fully oxidized form, which restricts the operating potential of such materials and supposes the use of an anode material in its lithiated state. Reduced forms of quinonic structures could represent examples of lithiated organic-based cathode able to deintercalate Li+ at potentials higher than 3 V thanks to substituent effects. Having previously recognized the unique electrochemical properties of the C6O6-type ring, we have designed then elaborated through a simple three-step method the lithiated salt of 3,6-dihydroxy-2,5-dimethoxy-p-benzoquinone, a new redox amphoteric system deriving from the tetralithium salt of tetrahydroxy-p-benzoquinone. Electrochemical investigations have particularly revealed that such an air-stable salt may reversibly deintercalate one Li+ upon charging with a practical capacity of about 100 mAh g1 at near 3 V with, however, a polarization effect. Better capacity retention was successfully obtained by simply adding an adsorbing additive. A tetrahydrated form of the studied salt was also characterized from XRD and first-principles calculations. Various levels of theory were probed including DFT with classical functionals (LDA, GGA, PBEsol, revPBE) and models for dispersion corrections to DFT. One of the modified dispersion-corrected DFT schemes, related to a rescaling of both van der Waals radii and s6 parameter, provides significant improvements for the description of this crystal kind over other treatments. We then applied this optimized approach to the screening of hypothetical frameworks for the delithiated phases and to the search for the anhydrous structure.