MnO-based materials are one of the most promising cathodes for rechargeable zinc ion batteries (ZIBs) owing to their high energy density and abundant resources. However, the notorious electronic conductivity and large volumetric expansion issues have severely restricted their practical application. Herein, 1D nanowires (NWs) with abundant internal void space, composed of ultra-small MnO@C nanoreactors, is proposed to get rid of the above dilemma. Specifically, carbon layer dramatically enhances electrically conductive, the elaborated constructed void space between MnO@C nanoreactors effectively avoid the physical clogging and restacking of MnO, relieving the strain upon charge and discharge process, and ultimately ensuring cathode satisfactory integrity maintenance, different from traditional 1D NWs composite architecture. As expected, the NWs constructed by MnO@C nanoreactors exhibit the superior cycling stability (102.9% capacity retention after 2000 cycles) and good rate performance. Moreover, we firstly construct freestanding MnO@C NWs/CNTs film as cathode and assemble a quasi-solid-state ZIB by using soaking-free PAM hydrogel electrolyte. The device without extra binders and additives affords an impressive reversible capacity of 357.2 mAh g−1 at 0.1 A g−1, and remarkable volumetric energy density of 20.8 mWh cm−3 (higher than commercial Li thin-film battery). Furthermore, our soft-packaged ZIBs also exhibits satisfactory flexibility and high safety.
A novel 3D ZIF-8 network-reinforced polyethylene oxide (PEO) composite polymer electrolyte (Z-C-PAN-PEO) is successfully built, in which the network with an interpenetrated structure is tactfully developed by in situ assembling ZIF-8 nanoparticles on electrospinning carboxylated polyacrylonitrile (C-PAN) nanofiber surfaces. ZIF-8 with high porosity and unsaturated open metal sites will act as the bridge between C-PAN nanofibers and the PEO matrix. It is proven that the selected ZIF-8 can play a significant role in facilitating Li+ conduction and transference by effectively interacting with the oxygen atoms of C–O–C to promote the segmental movement of PEO and immobilizing TFSI– anions to release more free Li+. The 3D interpenetrating structure of Z-C-PAN further enables the conduction channels more consecutive and long-ranged, endowing the Z-C-PAN-PEO electrolyte with an optimum ionic conductivity of 4.39 × 10–4 S cm–1 and a boosted Li+ transference number of 0.42 at 60 °C. Other improvements occurring in the reinforced electrolytes are the broaden electrochemical stability window of ∼4.9 V and sufficient mechanical strength. Consequently, the stable Li-plating/stripping for 1000 cycles at 0.1 mA cm–1 witnesses the splendid compatibility against Li dendrite. The cycling performance of LiFePO4/Z-C-PAN-PEO/Li cells with a reversible capacity of 116.2 mAh g–1 after 600 cycles at 0.2 C guarantees the long-term running potential in lithium metal batteries. This study puts forward new insights in designing and exploiting the active role of MOFs for high-performance solid polymer electrolytes.
Abstract In this paper, a pre‐anodized carbon paste electrode (PACPE) is fabricated by a simple electrochemical pretreatment method, which can be used for the simultaneous determination of uric acid (UA) and ascorbic acid (AA). The influencing mechanism of the acidity on the size of oxidation peak current ( i p,a ) of UA and AA is discussed in detail. According to the results, in different pH conditions, the intensity of hydrogen bonding between UA, AA and the surface of PACPE, the degree of reduction reaction at the auxiliary electrode, and the structural configurations of UA and AA with different species in reaction system have evident influence on the size of oxidation peak current. In pH 7.00 phosphate buffer solution, the calibration curves for UA and AA are obtained in the range of 5.0 x 10 ‐7 –5.0 x 10 ‐5 mol/L and 3.0 x 10 ‐5 –5.0 x 10 ‐3 mol/L, respectively. The detection limits for UA and AA are found to be 2.0 x 10 ‐8 mol/L and 1.2 x 10 ‐6 mol/L, respectively. This proposed method has been successfully applied to determine UA and AA in human urine simultaneously with satisfactory results.
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