Portable power sources and grid-scale storage both require batteries combining high energy density and low cost. Zinc metal battery systems are attractive due to the low cost of zinc and its high charge-storage capacity. However, under repeated plating and stripping, zinc metal anodes undergo a well-known problem, zinc dendrite formation, causing internal shorting. Here we show a backside-plating configuration that enables long-term cycling of zinc metal batteries without shorting. We demonstrate 800 stable cycles of nickel–zinc batteries with good power rate (20 mA cm−2, 20 C rate for our anodes). Such a backside-plating method can be applied to not only zinc metal systems but also other metal-based electrodes suffering from internal short circuits.
Ionic liquid (IL) modified reduced graphene oxide (rGO-IL) nanosheets anchoring manganese oxide (Mn 3 O 4 ) are synthesized via a facile solution-based growth mechanism and applied to a Zn-air battery as an effective electrocatalyst for the oxygen reduction reaction (ORR). In this study, the IL moiety in these composites increases not only the conductivity of the system, but also the electrocatalytic activity compared to pristine rGO, together with the synergic effect of facilitating the ORR with the intrinsic catalytic activity of Mn 3 O 4 . Based on the Koutecky-Levich plot, we suggest that the ORR pathway of these composites is tunable with the relative amount of Mn 3 O 4 nanoparticles supported onto the graphene sheets; for example, the ORR mechanism of the system with a lower Mn 3 O 4 (19.2%) nanoparticle content is similar to a Pt/C electrode, i.e., a one-step, quasi-4-electron transfer, unlike that with a higher Mn 3 O 4 (52.5%) content, which undergoes a classical two-step, 2-electron pathway. We also demonstrate the potential of these hybrid rGO-IL/Mn 3 O 4 nanoparticles as efficient catalysts for the ORR in the Zn-air battery with a maximum peak power density of 120 mW cm À2 ; a higher performance than that from commercial cathode catalysts.
We report metal-free electrocatalysts to enhance utilization of dissolved and gaseous oxygen during oxygen reduction reaction (ORR).Proper balance between hydrophobicity and hydrophilicity is achieved using reduced graphene oxide (rGO) and polyelectrolyte functionalized multiwalled carbon nanotubes (pMWNTs). In this unique architecture, both two-and three-phase reactions in ORR can be maximized with a quasi-four-electron pathway.
Thirteen types of fuel pellets were prepared from hydrothermally treated hospital solid waste, hydrothermally treated rice straw, pyrolytic plastic waste residue, rice straw, and Sakhalin fir residue using a flat die pellet machine. Different pellet properties such as pellet density, pellet durability, aspect ratio, physicochemical characteristics, and gross calorific value (GCV) were evaluated as well as compared concerning the European standard specification for residential/commercial densified fuels. In addition, the quality of pellets was compared with coal. The results showed that the pellets made only with hydrothermally treated hospital solid waste, hydrothermally treated rice straw, pyrolytic plastic waste residue, and rice straw failed to meet few individual criteria (<3 wt% ash content, <10 wt% moisture content, <0.03 wt% chlorine content, >96.5 wt% pellet durability, and >600 kg/m3 pellet density) of the European standard specifications. However, most of the mixed fuel pellets satisfied the requirement of pellet properties according to the European standard specification. In particular, up to 16.70 wt% hydrothermally treated rice straw, 1.50 wt% hydrothermally treated hospital solid waste, and 4.76 wt% of pyrolytic plastic waste residue can be blended with Shakhalin fir residue to produce low-chlorine fuel pellets. The gross calorific value of pellets made from the mixture of hydrothermally treated wastes and pyrolytic plastic waste residue (around 22 MJ/kg) showed similar results to that of coal. In the case of mixed pellets, the presence of these hydrothermally treated wastes and pyrolytic plastic waste residue valorized the fuel pellet quality. The main outcome of this study was the production of low chlorine biomass fuel pellets of high gross calorific values blended with hydrothermally treated wastes and pyrolytic waste residues, which opens a new door for utilizing waste in a better way, especially hospital solid waste.
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