Manipulating Local Concentration of Hexafluorophosphate Anion in Dimethyl Carbonate to Improve the Performance of Dual‐Ion Batteries

ABSTRACT The development of high‐performance dual‐ion batteries (DIBs) hinges on understanding anion intercalation chemistry, which remains less explored than its cationic counterpart. While high‐concentration electrolytes can enhance anion storage in graphite cathodes, the independent role of anion solvation structure is ambiguous. Herein, we systematically tailor the PF 6 − solvation structure by designing a series of localized high‐concentration electrolytes (LHCEs) based on LiPF 6 ‐DMC solution, using TTE as a diluent. This strategy uniquely reduces coordinating DMC and increases anion‐solvent separation, thus effectively loosening the solvation environment without altering the salt concentration. Combining FTIR, NMR, MD, and in/ex situ XRD, we reveal the correlation between DMC‐PF 6 − solvation structures and the anion storage behavior in graphite cathodes. Anions with looser solvation sheaths exhibit more efficient de‐intercalation kinetics and induce more ordered two‐phase transitions, improving reversible capacity and cycling stability. The optimized LHCE delivers multifunctional performance: exceptional flame retardancy, low‐temperature operation (80 mAh g −1 over 3000 cycles at −10°C, stable), and markedly reduced self‐discharge. This work shifts the paradigm from electrolyte compositional tuning to precise solvation‐structure engineering. The rational design of electrolyte solvation structures can effectively regulate anion intercalation chemistry, providing a key strategy for developing high‐performance, safe, and wide‐temperature‐range DIBs.