Mn-Co-Ni-O (Mn:Co:Ni=1.74:0.72:0.54, MCN) thin films with single cubic spinel structure were prepared on Si substrates by metal organic solution deposition (MOSD) method at different annealing temperatures. The effects of annealing temperature on the phase component, crystalline microstructure, surface morphology and electrical properties of the MCN thin films were studied. According to the results of x-ray diffraction pattern, the MCN thin film annealed at 650 had spinel structure. Observation with field emission scanning electron microscope (FE-SEM) on the MCN thin films showed that the grain size increased with increasing annealing temperature. The resistance measured at room-temperature was 18.143, 12.457, 2.435 and 3.141MΩ for the MCN thin films annealed at 650, 700, 750 and 800, respectively. The values of thermistor constant (B30/85) and activation energy (Ea) were in the range of 3260-4840K and 0.28-0.42eV, respectively.

Zinc gluconate is widely used as a nutrient because the zinc ion (Zn2+) participates in the synthesis of enzymes. However, the improper management of expired waste zinc gluconate could result in the influx of excessive zinc ions into the environment and thus cause damage to organisms. For this purpose, expired waste zinc gluconate was first recycled through a hydrothermal reaction and pyrolysis for a zinc oxide (ZnO)/carbon (C) composite. Furthermore, the effect of the hydrothermal reaction time on the morphology and electrochemical performance of the zinc oxide/carbon composite was also investigated. The results showed that the combination mode of zinc oxide with carbon microspheres could be controlled by tailoring the hydrothermal reaction time. The carbon content of the composite with a hydrothermal time of 5 h (ZnO/C-5h) was 53 wt%, slightly lower than the 55 wt% of the composite with a hydrothermal time of 9 h (ZnO/C-9h). Resultantly, the ZnO/C-5h anode exhibited higher electrochemical performance due to better phase interface. For example, the reversible discharge capacity of the ZnO/C-5h anode remained 270 mAh/g at 1000 mA/g for 500 cycles, higher than the 183 mAh/g of the ZnO/C-9h anode. Better phase interface and the synergistic effect may contribute to better electrochemical performance. These results could provide a recycling paradigm for expired waste zinc gluconate.

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As one common industrial waste liquid, waste copper (Cu) etchant can seriously pollute the environment if it is unreasonably managed. Herein, tetrahedron-like copper (I) chloride (CuCl) crystals were extracted from waste copper etchant by way of facile electrodeposition, and the effect of the electrodeposition time on the lithium (Li)-storage capacity of the copper (I) chloride crystal was further investigated. The results showed that the copper (I) chloride crystal had a regular tetrahedral morphology, and the density of the regular tetrahedral particles gradually increased with the extension of the electrodeposition time from 5 to 15, 20 and 25 s. Correspondingly, the reversible lithium-storage capacity of the copper (I) chloride anode experienced an initial increase and a subsequent decrease. In detail, when cycling at 2 C for 250 cycles, the reversible discharge capacity of the copper (I) chloride anode increased from 187·3 mAh/g at 5 s to 284·5 mAh/g at 15 s and then decreased to 191·9 mAh/g at 20 s and to 125·3 mAh/g at 25 s, indicating that 15 s may be the most optimal electrodeposition time. Excessive copper (I) chloride particles may result in poor performance due to the poor inherent conductivity of copper (I) chloride. Such efforts would alleviate environmental pollution and facilitate the circular economy of wastes.

The wide application and oversupply of various medicines are inevitably accompanied by the production of massive amounts of expired medicines, which can trigger the environmental contamination and waste of resources if these are not reasonably managed. For this reason, the efforts were made to recycle two expired medicines (lithium carbonate (Li2CO3) and ferrous sulfate (FeSO4) tablets) simultaneously into magnesium ion-doped lithium iron phosphate (LiFePO4; LFP)/carbon (C) powders through a facile high-temperature solid-state reaction. In addition, the economic feasibility was analyzed and discussed. The results suggested that 0·51 wt% magnesium ions were successfully doped into the lithium (Li) site of LFP/carbon, and the corresponding molecular formula was Li0·92Mg0·04FePO4/C, which resulted in the double effects: a decrease in the unit cell volume and an increase in the electronic conductivity. Furthermore, the magnesium ion/LFP/carbon cathode also exhibited better electrochemical lithium-storage performance compared with the undoped LFP/carbon cathode, indicating high application feasibility in lithium-ion batteries. Additionally, the recycling process was economically profitable, which would stimulate the development of the circular economy of waste expired medicines and lithium-ion batteries.