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Quasi‐solid polymer electrolyte (QPE) lithium (Li)‐metal battery holds significant promise in the application of high‐energy‐density batteries, yet it suffers from low ionic conductivity and poor oxidation stability. Herein, a novel self‐built electric field (SBEF) strategy is proposed to enhance Li+ transportation and accelerate the degradation dynamics of carbon‐fluorine bond cleavage in LiTFSI by optimizing the termination of MXene. Among them, the SBEF induced by dielectric Nb4C3F2 MXene effectively constructs highly conductive LiF‐enriched SEI and CEI stable interfaces, moreover, enhances the electrochemical performance of the QPE. The related Li‐ion transfer mechanism and dual‐reinforced stable interface are thoroughly investigated using ab initio molecular dynamics, COMSOL, XPS depth profiling, and ToF‐SIMS. This comprehensive approach results in a high conductivity of 1.34 mS cm−1, leading to a small polarization of approximately 25 mV for Li//Li symmetric cell after 6000 h. Furthermore, it enables a prolonged cycle life at a high voltage of up to 4.6 V. Overall, this work not only broadens the application of MXene for QPE but also inspires the great potential of the self‐built electric field in QPE‐based high‐voltage batteries. [ABSTRACT FROM AUTHOR]

The development of effective, stable anhydrous proton‐conductive materials is vital but challenging. Covalent organic frameworks (COFs) are promising platforms for ion and molecule conduction owing to their pre‐designable structures and tailor‐made functionalities. However, their poor chemical stability is due to weak interlayer interactions and intrinsic reversibility of linkages. Herein, we present a strategy for enhancing the interlayer interactions of two‐dimensional COFs via importing planar, rigid triazine units into the center of C3‐symmetric monomers. The developed triazine‐core‐based COF (denoted as TPT‐COF) possesses a well‐defined crystalline structure, ordered nanochannels, and prominent porosity. The proton conductivity was ≈10 times those of non‐triazinyl COFs, even reaching up to 1.27×10−2 S cm−1 at 160 °C. Furthermore, the TPT‐COF exhibited structural ultrastability, making it an effective proton transport platform with remarkable conductivity and long‐term durability. [ABSTRACT FROM AUTHOR]