Cosolvation Accelerated Desolvation-Coupled Charge Transfer for Low-Temperature Zinc Metal Batteries

Anti-freezing cosolvents are commonly introduced to maintain electrolyte fluidity at subzero temperatures. However, their weak participation in the primary Zn²⁺ solvation sheath can leave desolvation-coupled interfacial kinetics largely unimproved. Here, we introduce a molecular cosolvation-promotion strategy that activates an otherwise passive anti-freezing solvent. Tris(2-chloropropyl) phosphate (TCPP), featuring an electron-rich phosphoryl center and a bulky, weakly solvating periphery, promotes methanol incorporation into the primary Zn²⁺ solvation sheath. Remarkably, although the coordination number of TCPP is only 0.17, its addition increases the methanol coordination number from 0.21 to 1.19 while decreasing the water coordination number from 4.01 to 3.07. This coordination amplification lowers the apparent activation energy for desolvation-coupled charge transfer from 18.46 to 13.91 kJ mol^-1 and preserves an ionic conductivity of 4.6 mS cm^-1 at -40°C. Meanwhile, preferential interfacial adsorption of TCPP excludes reactive water, homogenizes the Zn²⁺ flux, and suppresses corrosion and dendritic deposition. Consequently, Zn||Zn cells operate stably for over 2700 h at -40°C, while Zn||MnVO full cells retain 84.8% of their capacity after 8000 cycles at -20°C. This work establishes molecular promotion of cosolvent coordination as a general electrolyte-design principle for decoupling anti-freezing fluidity from sluggish subzero charge-transfer kinetics.