Abstract: Calcium additive was added into the active material (zinc oxide) of the pasted zinc electrodes using directly chemical reaction, chemical co-precipitation and physical mixture of zinc oxide and calcium hydroxide. SEM images show that the sample prepared by directly chemical reaction is tetragonal shape and the sample prepared by chemical co-precipitation is hexagonal shape. XRD analyses show that these two samples are calcium zincate crystals. Shapes of calcium zincate crystals result from different prior growth direction of crystal in the preparation process of calcium zincate. The charge/discharge performance, discharge capacity, cycle life and surface pattern of the pasted zinc electrodes were studied. Constant current charge/discharge and X-ray radiographs indicatethat the charge/discharge performance and surface uniformity of the pasted zinc electrodes with calcium zincate are better than those with physical mixture of zinc oxide and calcium hydroxide. The performance of the pasted zinc electrode with calcium additive is always prior to that of the calcium-free pasted zinc electrodes.
Effects of calcium additive on performance of pasted zinc electrode
Abstract:
Calcium additive was added into the active ma terial (zinc oxide) of th e pasted zinc electrodes using directly chemical reaction, chemical co precip ita tion and physical mixture of zinc oxide and calcium hydroxide. SEM images show t hat the sample prepared by directly chemical reaction is tetragonal shape and t he sample prepared by chemical co precipitation is hexagonal shape. XRD analys es show that these two samples are calcium zincate crystals. Shapes of cal ciu m zincate crystals result from different prior growth direction of crystal in th e preparation process of calcium zincate. The charge/discharge performance, di scharge capacity, cycle life and surface pattern of the pasted zinc electrodes w ere studied. Constant current charge/discharge and X ray radiographs indicate that the charge/discharge performance and surface uniformity of the pasted zin c electrodes with calcium zincate are better than those with physical mixture of zinc oxide and calcium hydroxide. The performance of the pasted zinc electrode with calcium additive is always prior to that of the calcium free pasted zinc e lectrodes.
Fig.5 Charge/discharge curves for pasted zinc electrodes
(a) —3rd cycle; (b) —28th cycle1—Zinc electrode with calcium zincate of tetragonal-shape;2—Zinc electrode with calcium zincate of hexagonal-shape;3—Zinc electrode with physical mixture of zinc oxide and calcium hydroxide;4—Zinc electrode with pure zinc oxide
图6 放电容量与循环次数的关系曲线
Fig.6 Curves of discharge capacity vs cycle numbe r (Symbols are same as those in Fig.5)
Fig.7 X-ray radiographs of pasted zinc electr odes after 75 charge/discharge cycles
(a) —Zinc electrode with calcium zincate; (b) —Zinc electrode with physical mixture of zinc oxide and calcium hydroxide; (c) —Zinc electrode with pure zinc oxide