Combating Solvent Concentration Polarization for Ultrafast and Highly Stable Lithium Batteries at −60 oC

Abstract

The imperative for reliable lithium batteries under extreme low-temperature (LT) conditions has revived interest in organic electrodes, yet their practical deployment is frustrated by severe electrode dissolution and sluggish Li⁺ desolvation kinetics. Here, we uncover solvent concentration polarization between the electric double layer (EDL) and bulk electrolyte as a hitherto-overlooked but decisive degradation mechanism. This polarization reshapes the EDL into a solvent-rich domain, elevating the desolvation barrier and amplifying solvent-electrode interactions that exacerbate dissolution. Guided by this insight, we engineer a highly depolarized solvent that suppresses EDL solvent aggregation and restructures the solvation structure from solvent-dominated to anion-enriched. The resulting electrolyte achieves an exceptional ionic conductivity of 0.51 mS cm⁻¹ at −60 ^oC and a high Li⁺ transference number of 0.65, while fostering a robust, inorganic-rich electrode|electrolyte interphase that mitigates dissolution. Consequently, even at −60 ^oC, the Li||DSR (Disodium rhodizonate) cell affords an outstanding capacity of 184.3 mAh g⁻¹ and remarkable cycling stability over 2000 cycles with an ultralow decay rate of only 0.0057% per cycle. This strategy proves generalizable to other organic electrodes, establishing the combating of solvent concentration polarization as a guiding principle for ultrafast-cycling and long-life lithium batteries under extreme LT conditions.