A universal chemical strategy towards the use of diluent for carbonate localized high-concentration electrolytes

The localized high-concentration electrolytes (LHCE) promise desolvation reactions on the graphite anode surface while effectively suppressing undesirable side reactions. However, a major challenge for carbonate-based LHCE design lies in the complicated dipole-dipole (d-d) interactions between diluents and solvents, induced by the highly polar carbonate solvents, e.g. ethylene carbonate (EC), giving raise to electron cloud rearrangement and coordinating ability of the diluent. Here, using the location of the rearranged electrons as an identification, we develop an innovative principle that can decouple the d-d interactions with diluent coordination from origin. In this case, a quasi-coordinating diluent can be identified via strongly polar bonds enriching electron, e.g. CdbndO in Bis(2,2,2-trifluoroethyl) carbonate, which generates strong Li⁺-diluent interactions and blocked desolvation process. Conversely, through weakly polar bonds enrichment, e.g. C-F bonds, a non-coordinating diluent is classified and shows negligible coordination ability. Further, combined with electrostatic potential calculation, charge displacement in diluent-EC complex is performed to quantitatively determine the d-d interactions, and thereby 1, 2-difluorobenzene stands out among non-coordinating diluents and delivers the lowest charge displacement of 0.004, promoting fastest Li⁺ desolvation kinetics and supporting a 4C fast-charging operation over 6000 cycles, showing a generalizable electrolyte design towards extreme working conditions.