Intrinsically Decoupled Coordination Chemistries Enable Quasi‐Eutectic Electrolytes with Fast Kinetics toward Enhanced Zinc‐Ion Capacitors

Abstract

AbstractEutectic electrolytes show potential beyond conventional low‐concentration electrolytes (LCEs) in zinc (Zn)‐ion capacitors (ZICs) yet suffer from high viscosity and sluggish kinetics. Herein, we originally propose a universal theory of intrinsically decoupling to address these issues, producing a novel electrolyte termed “quasi‐eutectic” electrolyte (quasi‐EE). Joint experimental and theoretical analyses confirm its unique solution coordination structure doped with near‐LCE domains. This enables the quasi‐EE well inherit the advanced properties at deep‐eutectic states while provide facilitated kinetics as well as lower energy barriers via a vehicle/hopping‐hybridized charge transfer mechanism. Consequently, a homogeneous electroplating pattern with much enhanced Sand's time is achieved on the Zn surface, followed by a twofold prolonged service‐life with drastically reduced concentration polarization. More encouragingly, the quasi‐EE also delivers increased capacitance output in ZICs, which is elevated by 12.4 %–144.6 % compared to that before decoupling. Furthermore, the pouch cell with a cathodic mass loading of 36.6 mg cm−2 maintains competitive cycling performances over 600 cycles, far exceeding other Zn‐based counterparts. This work offers fresh insights into eutectic decoupling and beyond.