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Cathode design is indispensable for building Li-O2 batteries with long cycle life. A composite of carbon-wrapped Mo2C nanoparticles and carbon nanotubes is prepared on Ni foam by direct hydrolysis and carbonization of a gel composed of ammonium heptamolybdate tetrahydrate and hydroquinone resin. The Mo2C nanoparticles with well-controlled particle size act as a highly active oxygen reduction reactions/oxygen evolution reactions (ORR/OER) catalyst. The carbon coating can prevent the aggregation of the Mo2C nanoparticles. The even distribution of Mo2C nanoparticles results in the homogenous formation of discharge products. The skeleton of porous carbon with carbon nanotubes protrudes from the composite, resulting in extra voids when applied as a cathode for Li-O2 batteries. The batteries deliver a high discharge capacity of ≈10 400 mAh g−1 and a low average charge voltage of ≈4.0 V at 200 mA g−1. With a cutoff capacity of 1000 mAh g−1, the Li-O2 batteries exhibit excellent charge-discharge cycling stability for over 300 cycles. The average potential polarization of discharge/charge gaps is only ≈0.9 V, demonstrating the high ORR and OER activities of these Mo2C nanoparticles. The excellent cycling stability and low potential polarization provide new insights into the design of highly reversible and efficient cathode materials for Li-O2 batteries. [ABSTRACT FROM AUTHOR]

Lithium-oxygen batteries with an exceptionally high theoretical energy density have triggered worldwide interest in energy storage system. The research focus of lithium-oxygen batteries lies in the development of catalytic materials with excellent cycling stability and high bifunctional catalytic activity in oxygen reduction and oxygen evolution reactions. Here, a hierarchically porous flower-like cobalt-titanium layered double oxide on nickel foam with intercalated anions of bistrifluoromethane sulfonamide (TFSI) is designed and prepared. When used as a binder-free cathode for lithium-oxygen batteries, this material exhibits low polarization (initial polarization of 0.45 V) and superior cycling stability (80 cycles at a current density of 100 mA g−1 at full discharge/charge). The high electrochemical performance of the cathode material is attributed to the good dispersion of binary elements in its host layer and good compatibility with lithium bistrifluoromethane sulfonamide electrolyte induced by intercalated guest anions of TFSI within its interlayer. This work provides a novel strategy for the fabrication of binder-free cathodes based on layered double oxides for high-performance lithium-oxygen batteries. [ABSTRACT FROM AUTHOR]

A novel binder-free electrode for lithium–oxygen batteries has been prepared by electrodepositing a Co3O4 layer onto a pretreated TiO2 fiber mesh, formed on nickel foam by an electrospinning method. The Co3O4 depositing layer is composed of Co3O4 nanoflakes, forming a uniform flower-like porous structure. The Co3O4 nanoflakes within the depositing layer provide a large amount of catalytic active sites for oxygen evolution and reduction reactions. The three-dimensional porous network of the Co3O4 depositing layer can not only facilitate the transportation of ions and electrolyte within the electrode, but also provide plenty of space to accommodate Li2O2 species formed during the discharge process. The Co3O4 spheres embedded in the TiO2 fiber mesh, formed by the treatment of a suspension of cobaltammine precipitate, function as anchors to prevent the detachment of the Co3O4 layer from the current collector, resulting in excellent structural and cycling stability. Only a slight specific capacity decay is observed at full discharge/charge after 80 cycles. This work demonstrates the important factors in the preparation of binder-free cathodes for high performance lithium–oxygen batteries. [ABSTRACT FROM AUTHOR]

• A Co-Mo 2 C/nitrogen-doped carbon nanotubes composite was synthesized. • The bimetallic design of co and Mo 2 C provided high catalytic activity during cycles. • High capacity and long cycle Li–CO 2 batteries were realized. Li–CO 2 batteries have received increasing attention due to their high theoretical energy density. However, the insulating Li 2 CO 3 formed in the discharge process is difficult to decompose in the charging process, resulting in high overpotentials, short cycle life, and poor rate capability. The rational design of cathode catalyst is crucial to form and decompose Li 2 CO 3 during the discharge-charge cycles. Here, a Co-Mo 2 C/nitrogen-doped carbon nanotube composite has been achieved and introduced as the catalyst cathode for the Li–CO 2 batteries. The bimetallic modified Co and Mo 2 C provide high catalytic activity during discharge and charge process, respectively. The assembled Li–CO 2 batteries exhibit a low overpotential of 1.12 V at 100 mA g −1 with an extremely high discharge capacity of 18,001 mAh g−1, and provide a long-term stability of 120 cycles with a limited capacity of 500 mAh g−1. The bimetallic catalyst cathode design provides an efficient strategy to realize the high-performance Li–CO 2 batteries. [Display omitted] [ABSTRACT FROM AUTHOR]