In aqueous rechargeable zinc–manganese dioxide batteries (ZMBs), some irreversible side reactions, such as Mn2+ dissolution, often lead to capacity fading over cycling. These side reactions play a crucial role in the capacity and cycle performance of the battery. The implementation of a bionic electrode microskin (EMS) composed of collagen hydrolysate to convert the irreversible side reactions into reversible reactions is reported. The proposed EMS effectively adsorbs and confines the Mn2+ ions around the cathode through van der Waals forces, hydrogen bonds, and/or ionic interactions, which makes the MnO2/Mn2+ reactions reversible during the charge/discharge process. Such Mn2+ dissolution reactions, with an ultrahigh theoretical capacity (617 mAh g‐1), contribute a large amount of capacity, ≈44% of the total specific capacity at a low scan rate. Based on these fundamental findings, the assembled ZMBs with an EMS display an unprecedented discharge capacity of 415 mAh g‐1 at 20 mA g‐1, which overcomes the theoretical capacity (308 mAh g‐1) limitation of the Zn2+ intercalation mechanism. More significantly, the EMS on all α‐, β‐, and γ‐MnO2 cathodes exhibits similar high capacity beyond the theoretical capacity of Zn intercalation and capacity retention enhancement after 3000 cycles.
The major carotenoids (β-carotene, γ-carotene, torulene, and torularhodin) were determined by high-performance liquid chromatography, with torulene present in the largest amount (167.0 μg/g), followed by torularhodin (113.4 μg/g), β-carotene (52.1 μg/g) and γ-carotene (15.4 μg/g). In addition, cis/trans torulene isomers were further identified by developing an HPLC-DAD coupled with an atmospheric-pressure chemical ionization (APCI) MS method, following isolation and purification torulene from crude pigments by column chromatography. A total of 8 torulene geometrical isomers were resolved within 60 min by employing a YMC C30 column and a binary gradient mobile phase consisting of methanol-methyl tert-butyl ether-water, (50:47.5:2.5, v/v/v) (A) and methanol-methyl tert-butyl ether-water, (8:90:2, v/v/v) (B). Geometrical carotenoid isomers behave differently with respect to bioavailability; therefore, it is of great importance to expand our knowledge on their biological roles to determine the appropriate method to separate torulene cis/trans isomers.
Friction and wear usually lead to huge energy loss and failure of machine pairs, which usually causes great economic losses. Researchers have made great efforts to reduce energy dissipation and enhance durability through advanced lubrication technologies. Single-layer coatings have been applied in many sectors of engineering, but the performance of single-layer coatings still has many limitations. One solution to overcome these limitations is to use a multilayer coating that combines different components with varied physical and chemical properties. In addition, multilayer coating with alternating layers only containing two components can lead to improved performance compared to a coating with only two different layers. This paper systematically reviews the design concept and properties of different types of multilayer coatings, including transition-metal nitride coatings, diamond-like carbon-based coatings, and other multilayer coatings. The inherent functional mechanisms of the multilayer structures are also detailed and discussed.
In aqueous rechargeable zinc-ion batteries (ARZIBs), aqueous electrolytes tend to initiate structure changes of metal oxides and conductive agents of the electrode, which leads to rapid capacity degradation. In this work, we report an artificial cathode−electrolyte interface (CEI) composed of paraffin that provides a trade-off between Zn 2+ intercalation kinetics and stability of the cathode materials. Such paraffin-based CEI can either suppress Mn 2+ dissolution and hence stabilize MnO 2 , or prevent water contact with conductive graphite to maintain its morphology and carbonaceous structure. As a result, the assembled aqueous Zn//MnO 2 and Zn//ZnMn 2 O 4 full battery with paraffin-based CEI delivered a superior capacity retention of 82% and 81% after 1000 cycles, 67% and 48% higher than the battery without CEI, respectively. More importantly, both Zn//MnO 2 and Zn// ZnMn 2 O 4 full battery also exhibit exceptional cycling stability even at a very high cathode mass loading of 23.6 and 25.2 mg cm −2 , respectively, which offers an ideal capacity retention of 73% and 78% after 5000 cycles. Such a unique CEI design on the cathode surface provides a general strategy to improve the cycle life of ARZIBs.
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