Quasi-Solid-State All-V2O5 Battery.

Solid-state symmetrical battery represents a promising paradigm for future battery technology. However, its development is hindered by the deficiency of high-performance bipolar electrodes and compatible solid electrolytes. Herein, a quasi-solid-state all-V2O5 battery constructed by a binder-free carbon fabric-V2O5 nanowires@graphene (CVOG) bipolar electrode and a softly cross-linked polyethylene oxide-based solid polymer electrolyte (SPE) is reported. The synergetic effect of nano-structuring of V2O5, hierarchical conductive network, and graphene wrapping endows the CVOG electrode with boosted reaction kinetics and suppressed vanadium dissolution. The cathodic and anodic reactions of CVOG are decoupled by electrochemical analysis, conceiving the feasibility of constructing all-V2O5 full battery. In manifesting the solid-state all-V2O5 battery, the robust and elastic SPE exhibits high ionic conductivity, tight/self-adaptable electrolyte-electrode contact, and a low charge-transfer barrier. The resultant solid-state full battery exhibits a high reversible capacity of 158 mAh g-1 at 0.1 C, good capacity retention of over 61% from 0.1 C to 2 C, and remarkable cycling stability of 77% capacity retention after 1000 cycles at 1 C, which surpass other solid-state symmetrical batteries. Hence, this work provides a practice of high-performance solid-state batteries with symmetrical configuration and is constructive for next-generation battery technology.

Enhanced resistive switching characteristics in Al2O3 memory devices by embedded Ag nanoparticles.

In this paper, Al2O3/Ag/Al2O3 sandwiched thin films were deposited by magnetron sputtering. Al2O3 thin films with embedded Ag nanoparticles (AgNPs) have been fabricated by adopting appropriate experimental parameters. The measurements on the resistive switching behaviors demonstrated that the embedded AgNPs could substantially enhance the local electric field, and effectively reduce the switching voltages, resulting in a sharply increased OFF/ON ratio up to 106 at 0.5 V. Furthermore, the cycling stability was considerably improved owing to the reduced randomness for the formation and rupture of conductive filaments (CFs). AgNPs could also contribute with movable Ag ions, and the Ti top electrode usually reacts with Al2O3 promoting the formation of oxygen vacancies. As a result, a hybrid CF with better high-temperature stability was induced. Comparatively, if the embedded Ag sublayer is smooth, the switching parameters become dispersive owing to the random formation and rupture of CFs, and the switching performance is deteriorated. A physical model was proposed to understand the effect of the embedded AgNPs.

Deep Phase Transition of MoS2 for Excellent Hydrogen Evolution Reaction by a Facile C-Doping Strategy.

Metallic 1T-phase MoS2 is considered to be the ideal electrocatalyst to carry out hydrogen evolution reaction (HER) because of favorable conductivity and sufficient active site compared with 2H-phase MoS2. Nevertheless, 1T-phase MoS2 is conventionally synthesized in a complicated process, with the production of an unstable product, which hinders their practical applications. Herein, we propose a facile approach through a carbon-doping-induced phase transition to obtain highly stable 1T-2H mixed MoS2 nanosheets. The phase transition process is characterized by Raman and X-ray photoelectron spectroscopy, as well as high-resolution transmission electron microscopy images and delivers a high phase purity of ∼60% for 1T-MoS2. According to density functional theory simulations and experimental results, C-doped 1T-2H mixed MoS2 has the advantages of abundant active sites, facilitated charge transfer rate, and high activity toward HER. The obtained C-doped MoS2 exhibits a superb HER electrocatalytic performance, with a current density of 10 mA cm-2 and the overpotential as low as 40 mV in 1 M KOH solution, and brilliant stability.

Fabrication of Li4Ti5O12-TiO2 Nanosheets with Structural Defects as High-Rate and Long-Life Anodes for Lithium-Ion Batteries.

Development of high-power lithium-ion batteries with high safety and durability has become a key challenge for practical applications of large-scale energy storage devices. Accordingly, we report here on a promising strategy to synthesize a high-rate and long-life Li4Ti5O12-TiO2 anode material. The novel material exhibits remarkable rate capability and long-term cycle stability. The specific capacities at 20 and 30 C (1 C = 175 mA g-1) reach 170.3 and 168.2 mA h g-1, respectively. Moreover, a capacity of up to 161.3 mA h g-1 is retained after 1000 cycles at 20 C, and the capacity retention ratio reaches up to 94.2%. The extraordinary rate performance of the Li4Ti5O12-TiO2 composite is attributed to the existence of oxygen vacancies and grain boundaries, significantly enhancing electrical conductivity and lithium insertion/extraction kinetics. Meanwhile, the pseudocapacitive effect is induced owing to the presence of abundant interfaces in the composite, which is beneficial to enhancing specific capacity and rate capability. Additionally, the ultrahigh capacity at low rates, greater than the theoretical value of spinel Li4Ti5O12, may be correlated to the lithium vacancies in 8a sites, increasing the extra docking sites of lithium ions.