Robust interfacial engineering construction to alleviate polysulfide shuttling in metal sulfide electrodes for achieving Fast-charge High-capacity lithium storages

Abstract

Robust cathode/electrolyte interphase (CEI) layer exhibits much importance in capacity retention. However, metal sulfide electrodes with unstable CEI layers suffer from fast capacity fading and poor Coulombic efficiency caused by notorious polysulfide shuttling effect. Herein, different from nanoparticle engineering, the morphology and state of CEI interface engineering are modulated via introducing highly active lithium bisfluorosulfonylimide (LiFSI) in the ether-based electrolyte. The presence and evolution of the uniform and robust LiF-Li3N-rich CEI layer in preventing polysulfide shuttling are fully understood by electrochemical measurements, interface-sensitive sum frequency generation spectroscopy, X-ray spectroscopies and electron microscopy. With the aid of the time-of-flight secondary-ion mass spectrometry, the three-dimensional architecture of CEI is re-depicted, showing the uniform coverage and thus inhibiting the polysulfide shuttling. As a result, the so-fabricated metal sulfide electrodes with continuous CEI layer exhibit much higher rate capacity and significantly-improved Coulombic efficiency than the controlled electrode samples. Even cycled at a high-power density of 6700 W kg−1 (5 C), the FeS2 electrode remains a high initial capacity (512 mA h g−1) and long lifespan up to 1000 cycles, depicting a blue-script of constructing robust CEI on the electrode for achieving the fast-charge electrodes.