A dual-functional interlayer for Li–S batteries using carbon fiber film cladded electron-deficient Li2B4O7

Abstract

The electron-deficient property of the atoms in functional materials endow them with tunable adsorption and catalysis effects on polysulfides, thus improving the performance of lithium–sulfur batteries. In this work, Li₂B₄O₇ nanoparticles, which have abundant electron deficiencies derived from the [BO₃] Lewis acid units, were uniformly cladded in the carbon nanofibers (LBO–CNF) and employed as interlayers for Li–S batteries. This functionalized interlayer expressed a high adsorption energy of ∼3.6 eV for polysulfides (e.g., Li₂S₆ and Li₂S₄) and effectively suppressed the polysulfides' shuttle behavior, delivering a high reversible capacity of 1242.6 mA h g⁻¹ at 0.2C and good cycling performance with a low fading rate of 0.068% per cycle at 1C, thus effectually inhibiting the phenomenon of self-discharge. Besides, the lithiation reaction kinetics was also effectively enhanced, enhancing the rate performance of the battery to 644 mA h g⁻¹ at 5C. This work provides a new strategy to enhance the electrochemical performance of Li–S batteries by applying the compounds of electronic-deficiency B-species and functionalized carbon.