CoOOH-coated Ni0.8Mn0.2(OH)2 samples were prepared by chemical coprecipitation method, and the cobalt mass fractions were 2.5%, 5%, 7.5% and 10%. X-ray diffraction measurements showed that the samples were mainly composed of β-Ni(OH)2, and some of the CoOOH-coated samples contained a small amount of impurities. Scanning electron microscopy measurements showed the CoOOH attachment on the surface of the sample particles. Cyclic voltammetry results showed that CoOOH coated on the surface of the sample could reduce the difference between oxidation and reduction peak potentials and increase the oxygen evolution potential of the electrode. Constant current chargedischarge results showed that sample CoOOH=5% yielded the highest discharge specific capacity and the best cycle stability with a discharge specific capacity of 282 mAh•g −1 at 100 mA•g −1. In the meantime, the discharge specific capacity of commercial β-Ni(OH)2 was 270 mAh•g −1. When the sample CoOOH=5% was cycled at 800 mA•g −1 , the discharge specific capacity did not decrease for 30 cycles, whilst other samples containing Co and commercial β-Ni(OH)2 showed different degrees of discharge specific capacity. Several experimental results proved that the sample with CoOOH mass fraction of 5% had good multiplier property and could improve the cycling stability of nickel electrode.
This study experimentally investigated the effects of the charge/discharge current, initial state of charge (SOC), internal resistance, and initial nominal capacity on the performance characteristics and efficiency of series-parallel battery to address the inconsistency problems of zinc-nickel single flow battery during the use of battery pack energy storage system. Experimental results show that the differences in charge/discharge current, initial SOC, and initial capacity change the inconsistency of battery pack. The difference in initial nominal capacity is the most influential factor, whereas the charge/discharge current is the least influential factor. Meanwhile, the inconsistency of internal resistance increases, which enlarges the energy loss of the battery pack and increases the temperature. The optimum operating current is below 30 A and the optimum deviation in initial SOC is within 10%, at which the inconsistency of the zinc-nickel single flow battery pack and the balance of the branch current are satisfactory.
In this study, a nickel-plated steel strip was used as the base material of zinc electrodes. The effect of composite additives, such as Sn 4+ , Ga 3+ ,and Pb 2+ , on zinc deposition and dissolution was tested using cyclic voltammetry, SEM, and constant-current charge/discharge. The cyclic voltammetry results showed that the composite additives could codeposit with zinc and easily form uniform crystal nuclei and dense deposit layers. The Tafel polarization curves demonstrated that the hydrogen evolution reaction on the electrodes in the solution with composite additives was weaker than those of the base solution and a single additive. The constant-current charge/discharge results presented that electrodes in the solution with composite additives obtained high coulombic efficiency but not significantly higher than that of the base solution and a single additive. The SEM results showed the smooth zinc deposit morphology with composite additives and small zinc deposit particles. The results of the selfdischarge test demonstrated that the self-discharge performance of the base solution clearly improved with the addition of composite additives and the residual capacity increased from 49.7% to 65.6% after 24 h in standby state.
This study aims to investigate the influence of different configurations of capacitive deionisation (CDI) cells on desalination performance. Based on the modified Donnan model, a three-dimensional transient model of a CDI desalination unit considering the coupling of solution flow, charge transport and electric field and potential was established, and the entire adsorption process was simulated. After conducting experiments to verify the accuracy of the model, four CDI units with different architectures were set first, after which the flow state of the solution in the four CDI units were compared, along with the influence on the desalination performances of the CDI units. Finally, the influences of different inlet velocities on the desalination performances of the CDI units were compared and analysed. Simulation results reveal the following: (1) if the boundary conditions are the same, compared with the plateinflow/outflow CDI unit, the middle hole of the plate flows into the two-hole outflow CDI unit, the flow from the middle of the square plate to the surrounding outflow CDI unit and the flow from the middle of the disk to the surrounding outflow CDI unit reduced the average flow velocities of the solutions in the flow passage to 34.04%, 16.88%, and 15.96%, respectively. This also resulted in the corresponding increase in the retention time of the solution in the flow passage by 40%, 44.52%, and 50.95%, resulting in better desalination performance than that of the plate-inflow/outflow CDI unit. (2) Compared with the three other types of CDI units, the one with middle holes flowing in and out at both ends of the plate generates a 0 m/s solution flow rate at the four corners, which cannot easily flow out, thus reducing the desalination performance of the CDI unit. (3) Apart from the inlet velocity boundary condition, all other boundary conditions are the same. Thus, improving the inlet flow rate can help transform the flow around the square plate into a middle-type CDI unit, and the disc into the flow around the CDI unit can effectively reduce desalination and lessen the impact of inlet velocity increase. This can also reduce the CDI unit desalination performance of less than flat CDI unit and flow type and transform a flat-type hole into two holes in the CDI unit.
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