High-Rate Discharge Performance

The results showed that the end charging potential of the nickel electrodes with flaky rare earth oxides were higher than that without rare earth oxide additives, but lower than that with normal rare earth oxide additives. In summary, flaky rare earth oxides increased the oxygen evolution potential and improved the reversibility of nickel electrodes (109). 

---

When the battery is discharged at a high current drain in a short time, it is desirable that the decrease in the discharge capacity would be low. In recent years, the high-rate discharge performance is one of the most important battery characteristics because the electric devices tend to need high power for its operation. 

A high discharge capacity of MAG is attained by both its characteristic texture and ideal hexagonal crystal structure. It excels in high-rate discharge performance, cyclicity, and electrode density. 

Table 8 shows the results of a comparative study of three types of batteries. One contains polyethylene separators and the other two contain linter pulp separators, but are different sizes. High rate discharge performances of the three batteries under low temperature are shown in Figure 8. The battery with the polyethylene separator outperforms the battery with linter pulp separators which is of the same size, and equals the performance of the one which is larger. 

Fig. 8 High rate discharge performance of XNS-40Z type battery under low temperature (discharge current 150A...

Visual examination is important as the first quality check for the weld. A good weld is required between each plate lug and the strap so that it will have minimum voltage drop during high-rate discharge performance. Electrical testing for short circuits is the second quality check before further assembly. 

FIGURE lO.lA Comparison of typical simulated photoflash high rate discharge performance characteristics for AA-size alkaline-manganese dioxide batteries produced in 1993 versus 1999. Courtesy of Eveready Battery Company.)... 

Table 30l1 High-rate discharge performance of Mallory lithium-sulphur dioxide hermetic D-size cell test performed on resistive leads after 6 months storage at 20°C...

This permits a reformulation of the cathode to include more active material and a lower internal resistance, as noted in Figure 2. The resultant lower internal resistance and higher active mass content produced a 30% increase in cell performance at high rate discharges. 

SIL (a coated, glass mat and rubber separator) separators have been found to be good choice for high rate discharging or cranking applications and for various types of gel cells. Recently Daramic DC UHMW PE has demonstrated excellent performance in these applications, as well. 

The alkaline cell has an open-circuit voltage of 1.5 V that can deliver 150 Wh/kg and 460 Wh/1. The reactions have fast kinetics and can deliver full capacity, even at high-rate discharges. Since its introduction in 1959, there has been a steady increase in performance of the alkaline cell as new materials and cell components were incorporated into the structure. The present alkaline cell designs are based on the use of nanostructured electrolytic manganese dioxide, a thinner polymer gasket seal with sealant to increase internal volume and improve shelf Ufe. Mercury has been eliminated by using new zinc alloy compositions. These improvements have resulted in about a 40 % improvement in performance over the same-size cells produced in 1959. 

---