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The "shuttle effect" of long-chain polysulfides and the low conductivity of elemental sulfur lead to the inferior cycling stability of lithium–sulfur batteries and imped their practical applications. Herein, Co3O4 nanoflakes with uniform macro pores distribution were synthesized via facile oil bath and calcination methods. Coupled with super P and coated on common polypropylene separators, they were expected to hinder the migration of lithium polysulfides (LiPSs) and accelerate the redox kinetics of polysulfides. Coin cells assembled with the Co3O4–super P interlayer exhibited a capacity of 760 mA h g−1 at 1 C, maintained 598 mA h g−1 after 350 cycles, and the decay rate of discharge capacity was only about 0.062% per cycle. Such high performance can be attributed to the synergistic effects between polar Co3O4 and conductive super P. The facile fabrication method and high performance make the Co3O4-super P interlayer a feasible material to apply in lithium-sulfur batteries. [ABSTRACT FROM AUTHOR]

MoO3−x nanobelts with different concentrations of oxygen vacancies were synthesized by a one-step hydrothermal process. XPS test results show that oxygen vacancies are distributed from the exterior to the interior of the MoO3−x nanobelts. As an anode material for lithium-ion batteries, MoO3−x-10 releases excellent rate capacitance. It can maintain a high specific capacitance of about 500 mA h·g−1 at a high current density of 1000 mA·g−1. In the aspect of cycling stability, MoO3−x-10 can retain a high specific capacity of 641 mA h·g−1 after cycling for 50 times at 100 mA·g−1 and 420 mA h·g−1 after cycling for 100 times at 500 mA·g−1. The coexistence of oxygen vacancies and low-valence Mo ions is conducive to the intercalation/de-intercalation of Li ions and to promoting redox reactions. It has been proved to be a significantly effective way in which oxygen vacancies can improve the integrated performance of MoO3−x nanobelts as anode materials. [ABSTRACT FROM AUTHOR]

Oxygen vacancy-enriched MoO3−x nanobelts with oxygen vacancies up to 20% (equal to MoO2.4) were synthesized and demonstrated fast reaction kinetics. An asymmetric supercapacitor was assembled with active carbon (AC) as the anode and the as-prepared MoO3−x nanobelts as the cathode. A new aqueous electrolyte of H2SO4/ethylene glycol (EG) was investigated and found to work appropriately at low temperatures, even at −25 °C. The MoO3−x nanobelts electrode possesses excellent specific capacitance, rate capacity (1230 F g−1 and 1220 F g−1 at 5 A g−1 and 50 A g−1, respectively) and cycle performance (100% after 38 000 cycles). Its energy and power densities reached 111 W h kg−1 and 803 W kg−1 or 50 W h kg−1 and 27 321 W kg−1 and maintained 80 W h kg−1 and 794 W kg−1 or 17 W h kg−1 and 23 565 W kg−1 at −25 °C. It is hypothesized that the coexistence of oxygen vacancies and low valence Mo ions enhanced both mass and charge transport kinetics and catalyzed the redox reactions. [ABSTRACT FROM AUTHOR]

3D-networked CNT–Ni3S2–CNT-A supported by Ni foam was rationally designed and synthesized via a multistep transformation approach. The intriguing and individual nanostructures endow the hybrid composites with outstanding electrochemical performance with an areal specific capacitance of 13 400 mF cm−2 at the current density of 10 mA cm−2 and an excellent rate capacity of 96.04% at 50 mA cm−2. The corresponding asymmetric supercapacitor assembled with CNT–Ni3S2–CNT-A (positive electrode) and active carbon (negative electrode) delivered a high energy density of 75.2 W h kg−1 at the power density of 2416 W kg−1, an excellent areal capacitance (425 mF cm−2 at 3 mA cm−2) and electrochemical cycling stability (90.6% retention after 10 000 cycles). The dual function of CNTs is responsible for the impressive electrochemical performance; the inner CNT provides more electrodeposition sites for higher capacitance while the outer high electrical conductivity CNT acts as highways for faster electron transportation. The rational design concept of this work is versatile and scalable for combining transition-metal sulfides with carbon materials for high performance supercapacitors. [ABSTRACT FROM AUTHOR]

The "shuttle effect" of long-chain polysulfides and the low conductivity of elemental sulfur lead to the inferior cycling stability of lithium-sulfur batteries and imped their practical applications. Herein, Co 3 O 4 nanoflakes with uniform macro pores distribution were synthesized via facile oil bath and calcination methods. Coupled with super P and coated on common polypropylene separators, they were expected to hinder the migration of lithium polysulfides (LiPSs) and accelerate the redox kinetics of polysulfides. Coin cells assembled with the Co 3 O 4 -super P interlayer exhibited a capacity of 760 mA h g -1 at 1 C, maintained 598 mA h g -1 after 350 cycles, and the decay rate of discharge capacity was only about 0.062% per cycle. Such high performance can be attributed to the synergistic effects between polar Co 3 O 4 and conductive super P. The facile fabrication method and high performance make the Co 3 O 4 -super P interlayer a feasible material to apply in lithium-sulfur batteries.

MoO 3-x nanobelts with different concentrations of oxygen vacancies were synthesized by a one-step hydrothermal process. XPS test results show that oxygen vacancies are distributed from the exterior to the interior of the MoO 3-x nanobelts. As an anode material for lithium-ion batteries, MoO 3-x -10 releases excellent rate capacitance. It can maintain a high specific capacitance of about 500 mA h·g -1 at a high current density of 1000 mA·g -1 . In the aspect of cycling stability, MoO 3-x -10 can retain a high specific capacity of 641 mA h·g -1 after cycling for 50 times at 100 mA·g -1 and 420 mA h·g -1 after cycling for 100 times at 500 mA·g -1 . The coexistence of oxygen vacancies and low-valence Mo ions is conducive to the intercalation/de-intercalation of Li ions and to promoting redox reactions. It has been proved to be a significantly effective way in which oxygen vacancies can improve the integrated performance of MoO 3-x nanobelts as anode materials.