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Long-term stable secondary batteries are highly required. Here, we report a unique microcapsule encapsulated with metal organic frameworks (MOFs)-derived Co3O4 nanocages for a Li-S battery, which displays good lithium-storage properties. ZIF-67 dodecahedra are prepared at room temperature then converted to porous Co3O4 nanocages, which are infilled into microcapsules through a microfluidic technique. After loading sulfur, the Co3O4/S-infilled microcapsules are obtained, which display a specific capacity of 935 mAh g−1 after 200 cycles at 0.5C in Li-S batteries. A Coulombic efficiency of about 100% is achieved. The constructed Li-S battery possesses a high rate-performance during three rounds of cycling. Moreover, stable performance is verified under both high and low temperatures of 50 °C and −10 °C. Density functional theory calculations show that the Co3O4 dodecahedra display large binding energies with polysulfides, which are able to suppress shuttle effect of polysulfides and enable a stable electrochemical performance. [ABSTRACT FROM AUTHOR]

Chemically and mechanically robust sulfur (S) cathodes are highly significant for high‐performance lithium‐sulfur (Li‐S) batteries. Herein, a novel 3D hydrogel@S composite as binder‐free high‐performance cathode is presented, which consists of a 3D conductive hydrogel polyaniline (PAN) scaffold coated with dense S particles. The 3D PAN@S composite exhibits polysulfides‐adsorptive performance, suitable structure for accommodating the volume change of S upon lithiation, and improved overall conductivity of the electrode. After cycling for 100 times at 0.2 C, the binder‐free 3D PAN@S composite shows a capacity of 816 mAh g−1, along with a Coulombic efficiency as high as 99.9%. A good electrochemical performance is also achieved when cycling at a high temperature of 50 °C. In addition, the adsorptive effect of PAN towards polysulfides is demonstrated through density functional theory calculations on the adsorption energies. [ABSTRACT FROM AUTHOR]

• A binder-free composite cathode is developed for Li-S batteries. • Stable capacity and recoverable rate-performance are achieved. • Density functional theory calculations show the composite has large binding energies with polysulfides. • Three-dimensional composite facilitates ion diffusion and electron transport. [Display omitted] A binder-free porous graphene like-C 3 N 4 nanoflakes/carbon cloth/sulfur lithium-sulfur battery cathode prepared through a thermal polymerization method is presented. On the basis of the density functional theory calculations on the bonds between g-C 3 N 4 and lithium polysulfides including Li 2 S 4 , Li 2 S 6 and Li 2 S 8 , it is found the cathode possesses robust binding energies towards polysulfides and an improved conductivity, which would enable a strong suppression for the transfer of the lithium polysulfides. The prepared porous binder-free cathode exhibits a high capacity of 892 mAh g−1 after cycling 250 times at 0.2 C and a well-recoverable rate-performance, which indicates a good potential to construct high-performance lithium-sulfur batteries for practical applications. [ABSTRACT FROM AUTHOR]

Hierarchical materials have been considered promising for secondary battery electrodes owing to their capability of accommodating volumetric change of active materials and providing short pathways for rapid transportation of ions and electrons. Herein, we present a rod-on-tube composite consisting of cobalt molybdate (CoMoO 4) nanotubes coating with polyaniline (PANI) hydrogel nanorods, which exhibits a high electrochemical performance as Li-ion battery anode. The hierarchical CoMoO 4 @PANI is prepared through in-situ polymerizing PANI nanorods on the CoMoO 4 nanotubes. The rod-on-tube structure could alleviate the volumetric change of CoMoO 4 during lithiation-delithiation, and improve conductivity for electron transfer. When cycling at 0.5 A g-1, the presented CoMoO 4 @PANI anodes exhibit a large capacity of 805 mAh g-1 after 150 cycles along with a Coulombic efficiency of 99%, which are both exceeding those of the pristine CoMoO 4. A well-recoverable rate-performance is achieved. Furthermore, the density of state (DOS) and band gap of the CoMoO 4 @PANI and pristine CoMoO 4 are also investigated by using density functional theory (DFT) calculations. Image 1 • A rod-on-tube CoMoO 4 @hydrogel composite anode is presented. • Rod-on-tube structure enables rapid transportation of ions and electrons. • CoMoO 4 @hydrogel composite exhibits a high electrochemical performance. • Density function theory calculations verify an improved conductivity. [ABSTRACT FROM AUTHOR]

• A novel polysulfides-immobilized composite is presented for Li-S battery. • The TiO 2 @PANI@S composite exhibits a high electrochemical performance. • Strong adsorption between the composite and polysulfides is presented. • Enhanced electron transfer and ion diffusion are achievable. Li-S batteries are promising new energy-storage systems owing to their high theoretical energy density. However, the volume-change and poor conductivity of S, and shuttle effect severely restrict applications. Here, we present a novel semispherical composite consisting of sulfur and polyaniline (PANI) hydrogel coating on a bowl-shaped hollow TiO 2. The TiO 2 @PANI@S composites show an excellent performance with a high capacity of 1058 mAh g−1 after 200 cycles at 0.2 C, and a stable Columbic efficiency of 99.8%. The composites also possess a recoverable rate-performance under repeated tests. The Li+ ion diffusion co-efficiency is studied, which indicates that the semispherical composite enables a rapid Li+ ion transportation. In addition, the density functional theory calculations confirm a strong adsorption of TiO 2 towards polysulfides including for Li 2 S 4 , Li 2 S 6 , and Li 2 S 8 , which efficiently suppress the shuttle effect. [ABSTRACT FROM AUTHOR]