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We report in this letter a new type of sealed rechargeable lithium–lithium oxide battery based on reversible interconversion between superoxide (LiO2) and lithium peroxide (Li2O2). A free-standing oxygenated group-rich reduced graphene oxide aerogel (OR-rGO) with decent mechanical properties is prepared through a hydrothermal method followed by slight drying in air at room temperature and applied as a cathode in oxygen-based beyond-intercalation Li batteries. In situ Raman spectroscopy, online electrochemical mass spectroscopy, and density functional theory calculations revealed the reversible stabilization of LiO2 by the oxygenated groups on rGO during the charge process. Based on the stability of LiO2 on oxygenated group-rich reduced graphene oxide, a new sealed lithium–lithium oxide battery via reversible Li2O2/LiO2 interconversion was realized with high operating potential up to 3.65 V and no O2 evolution. Excellent cycling stability was observed for 700 cycles at a cut-off capacitance of 0.6 mA h cm−2 and a current density of 0.6 mA cm−2. [ABSTRACT FROM AUTHOR]

The application of lithium–sulfur (Li–S) batteries is hindered by the severe shuttle effect and sluggish redox conversion kinetics of lithium polysulfides (LiPSs). Herein, holey amorphous dual transition metal (cobalt and iron) oxide-coated black phosphorus nanosheets (BP@FeCoO) have been synthesized and utilized as a sulfur host in Li–S batteries. From the compositional outlook, compared with the individual counterparts, the hybrid material of BP and amorphous FeCoO containing rich oxygen vacancies has enhanced adsorption ability and catalytic activity toward LiPSs, as well as improved electrical conductivity and Li-ion diffusion rate. From the structural feature perspective, the 2D nanosheets decorated with abundant meso/microporous channels greatly enlarge the surface area of the BP@FeCoO electrode, which offers sufficient active sites for accommodating sulfur active species and provides buffer space to withstand the volume changes during the charge/discharge process. Due to these compositional and structural superiorities, the Li–S battery with BP@FeCoO/S electrode exhibited excellent electrochemical performance with high cycle stability (fading rate of 0.040% per cycle at 1C) and outstanding rate capability (644.3 mA h g−1 at 5C). More impressively, with a high sulfur loading of 6.0 mg cm−2, the BP@FeCoO/S electrode showed a high capacity of 903.9 mA h g−1 at 0.2C. [ABSTRACT FROM AUTHOR]

Porous carbon-based materials are employed as sulfur hosts to overcome the problems of insulating nature and volume expansion during lithiation of sulfur cathodes in lithium–sulfur (Li–S) batteries to some degree. However, the shuttle effect and sluggish redox reaction kinetics of sulfur species result in unsatisfactory cycle life and sulfur utilization, hampering the practical application of Li–S batteries. In this work, meso-/microporous core-shelled MoC nanocrystal-embedded N-doped carbon microspheres (MoC/NC CSMSs) were prepared and further used as sulfur hosts. The tailored mesoporous core and microporous-thin shell cooperate to guarantee a high sulfur loading, good electrolyte penetration, improved structural stability, and relieved shuttle effect. Besides, the uniformly distributed MoC nanocrystals enhance the affinity to lithium polysulfides (LiPSs) via the formation of the Mo–S bond and accelerate the conversion kinetics of LiPSs by catalyzing the formation and decomposition of Li2S clusters. After sulfur loading, the MoC/NC/S CSMS electrode exhibits remarkable lithium storage properties with a high reversible capacity of 1370.3 mA h g−1 at 0.1C, outstanding rate performance, and ultra-long cycle life with a low capacity decay rate of 0.034% per cycle for 500 cycles at 1C. [ABSTRACT FROM AUTHOR]