No abstract

A composite consisting of cobalt and graphitic porous carbon (Co@GC-PC) is synthesized from bimetallic metal-organic frameworks and employed as the sulfur host for high-performance Li-S batteries. Because of the presence of a large surface area (724 m g) and an abundance of macro-/mesopores, the Co@GC-PC electrode is able to alleviate the debilitating effect originating from the volume expansion/contraction of sulfur species during the cycling process. Our in situ UV/vis analysis indicates that the existence of Co@GC-PC promotes the adsorption of polysulfides during the discharge process. Density functional theory calculations show a strong interaction between Co and LiS and a low decomposition barrier of LiS on Co(111), which is beneficial to the following LiS oxidation in the charge process. As a result, at 0.2C, the discharge capacity of the S/Co@GC-PC cathode is stabilized at 790 mAh g after 220 cycles, much higher than that of a carbon-based cathode, which delivers a discharge capacity of 188 mAh g.

No abstract

Cerium (Ce)‐modified Bi4Ti2.94W0.03Ta0.03O12 (BITWT) high Curie temperature ceramics (abbreviated as BITWT‐xCe) were fabricated by a conventional solid‐state sintering method. All BITWT‐xCe ceramics had an orthogonal phase, but the structural distortion of the Ce‐doped BITWT ceramics was higher than that of BITWT ceramics, which reduced symmetry and improved piezoelectric performance. The relative density (ρr) of BITWT‐xCe ceramics was greater than 97%. Under the same conditions, the hysteresis loop of BITWT‐0.04Ce ceramics had higher saturation than that of BITWT ceramics. The piezoelectric constant (d33) was enhanced, and the highest d33 of 24.7 pC/N at x = 0.04 was obtained, which was 25% higher than that of BITWT ceramics (d33 = 19.8 pC/N). In addition, the tentative conduction mechanism of BITWT‐xCe ceramics was also discussed. Two oxidations (Ce3+ and Ce4+) were present in the Ce‐doped BITWT ceramics.

No abstract