High-Performance Zinc-Ion Hybrid Supercapacitor from Guilin Sanhua Liquor Lees-Derived Carbon Materials.

Aqueous zinc-ion hybrid supercapacitors (ZHSCs) have attracted considerable attention because they are inexpensive and safe. However, the inadequate energy densities, power densities, and cycling performance of current ZHSC energy-storage devices are impediments that need to be overcome to enable the further development and commercialization of this technology. To address these issues, in this study, we prepared carbon-based ZHSCs using a series of porous carbon materials derived from Sanhua liquor lees (SLPCs). Among them, the best performance was observed for SLPC-A13, which exhibited excellent properties and a high-surface-area structure (2667 m2 g-1) with abundant micropores. The Zn//SLPC-A13 device was assembled by using 2 mol L-1 ZnSO4, SLPC-A13, and Zn foil as the electrolyte, cathode, and anode, respectively. The Zn//SLPC-A13 device delivered an ultrahigh energy density of 137 Wh kg-1 at a power density of 462 W kg-1. Remarkably, Zn//SLPC-A13 retained 100% of its specific capacitance after 120,000 cycles of long-term charge/discharge testing, with 62% retained after 250,000 cycles. This outstanding performance is primarily attributed to the SLPC-A13 carbon material, which promotes the rapid adsorption and desorption of ions, and the charge-discharge process, which roughens the Zn anode in a manner that improves reversible Zn-ion plating/stripping efficiency. This study provides ideas for the preparation of ZHSC cathode materials.

Enhancing thermal conductivity of polyimide composite film by electrostatic self-assembly and two-step synergism of Al2O3 microspheres and BN nanosheets.

To improve the perfection of a three-dimensional thermally conductive network in polyimide (PI) composite film and with respect to the economy and simplicity of processing, a strategy of the two-step synergism of Al2O3 microspheres and hexagonal boron nitride (BN) nanosheets was proposed. First, BN nanosheet-coated Al2O3 microspheres (Al2O3@BN) were prepared by electrostatic self-assembly method for the first step of the synergism. Then, the Al2O3@BN&BN/PI composite film containing Al2O3@BN and BN was fabricated by a two-step method for the second step of the synergism, and was systematically characterized. With an optimized mass ratio of 2 : 1 of Al2O3@BN to BN, the thermal conductivity of the 35 wt% Al2O3@BN&BN/PI composite film reached 3.35 W m-1 K-1, and was increased by 1664% compared to that of pure PI. The synergism of the Al2O3 and BN was the most significant in the Al2O3@BN&BN/PI composite film with the thermal conductivity, which was 36.6%, 23% and 22% higher than that of the Al2O3/PI, BN/PI and Al2O3@BN/PI composite films, respectively. The enhancement mechanism of heat conduction was clearly demonstrated. The BN coated on the surface of Al2O3 mainly played a bridging role between the Al2O3 and the BN network, which improved the perfection of the thermally conductive network. The Al2O3@BN segregated the PI matrix to construct the BN network with the typical segregated structure in the composite film, resulting in an efficient thermally conductive network. This work provided a novel strategy for the preparation of conductive polymer composites.

A reduced graphene oxide-borate compound-loaded melamine sponge/silicone rubber composite with ultra-high dielectric constant.

Herein, at first, graphene oxide (GO) was prepared by a modified Hummers' method, compounded with borates and then loaded onto a melamine sponge (MS) skeleton by an impregnation-reduction method to obtain a reduced graphene oxide (rGO)-borate compound (rGB)-loaded MS. Then, MS/rGB/silicone rubber (SR) composites were prepared by a vacuum infusion process. Moreover, the microstructures, electrical conductivity, and dielectric properties of the composites were investigated. The results showed that rGO presented a sheet-like structure, compounding with borates produced during the reduction of GO by sodium borohydride. rGB was co-loaded onto the MS skeleton, and a three-dimensional percolation network was successfully constructed in the MS/rGB/SR composite. In addition, there was an efficient synergistic effect between rGO and borates, which significantly improved the dielectric constant of the composites. At the rGO volume fraction of 1.89 vol%, the composite had the volume resistivity of 6.57 × 104 Ω cm, the ultra-high dielectric constant of 2.71 × 104 with the dielectric loss of 1.36 at 1 kHz, and the relatively low percolation threshold of 0.815 vol%. Furthermore, the composite exhibited high compression sensitivity at low compressive strains.