Polyanion Electrointercalation Enables Termination-Tailored Oligolayer Ti

Tailoring surface chemistry and achieving non-destructive interlayer exfoliation are crucial for controlling MXene properties. Conventional synthesis strategies typically involve damaging intercalation processes and yield MXenes with mixed surface terminations, compromising their functionality. Herein, we propose an anodic etching strategy to produce facilely delaminated, termination-tailored Ti3C2Tx from Ti3AlC2 in low-temperature alkali-chloroaluminate (AlCl3-NaCl-KCl) melts at 170 °C through the in situ electrochemical intercalation of polyanions (AlnCl3 n +1 -, n ≥ 1). Oligolayer Ti3C2Clx (MSE-Ti3C2Clx) was readily achieved via further gently exfoliating the etching product, preserving the original surface chemistry featuring oxygen depletion and uniform chlorine termination. As functional coatings, MSE-Ti3C2Clx significantly extended the cycling lifespan of Zn anodes to 5500 h at 2 mA cm-2 and 1 mAh cm-2, attributed to the tailored surface chemistry and oligolayer-induced ordered alignment that enabled efficient Zn2+ capture and uniform deposition. The strategy's versatility was also demonstrated by tailoring terminations (e.g., -Br, -NH) via molten salt composition engineering, providing a non-destructive pathway for MXene surface engineering and interlayer delamination, thereby unlocking their full potential for advanced energy applications.