Battery performance charge capacities

Battery performance is rated on the basis of the charge capacity, available energy, delivered power, and charge retention during OCV conditions for rechargeable systems, the coulombic efficiency and stability to repeated charge-discharge cycles are also important parameters. 

Figure 21.7 shows rate capability, temperature characteristics, cycle Ufe, and overcharge test of the above battery. The battery performances are exceUent The most important point is that this battery is highly safe. Figure 21.7d shows the result of the overcharge test. The temperature of the battery increased with increasing charge capacity, but it showed maximum temperature at 57°C and no further temperature increase was observed. Those batteries will be used for the electric tools, electric bike, hybrid vehicle, and pure electric vehicles (EV). 

With this background, we can estimate and design the battery performance in terms of the power and the actual capacity. To understand the power performance, we illustrate how to calculate the maximum power in Figure 5.6. If we can know the battery s internal resistance and assume that it is a certain constant value, the power characteristics can be estimated and is related to the state of charge, an upper current limit, and a lower voltage limit. 

Because the service is performed against preset parameters, the batteries are charged and discharged under true field conditions, a feature that provides accurate test results as well as fast service. Batteries with shorted, mismatched or soft cells are identified in minutes, their deficiencies displayed and, if necessary, the service halted. The derived battery capacities are organized into residual nd final capacities. Problems, such as insufficient capacity reserve at the end of field use, are easily identified to allow necessary corrections. 

Nickel hydroxide active material is provided by reacting nickel sulfate solution and an alkaline solution. A part of nickel of nickel hydroxide is substituted for Zn and Co for the improvement of the battery performance. The theory capacity of nickel hydroxide is 289 mAh/g by supposing one electron reaction. The utilization of nickel hydroxide of a sintered-type electrode is approximately 100 %, but that of a pasted-type electrode without a conductive additive is around 65 %. The improvement of the utilization is enabled by forming CoOOH conductive networks between nickel hydroxide particles. The cobalt compound (Co, CoO, Co(OH>2) is filled into the formed nickel substrate with nickel hydroxide as an additive. The Co compounds form a conductive network as CoOOH by charging. To improve the conductivity of the cobalt conductive layer, Co(OH)2 layer coating to the surface of nickel hydroxide particles and the oxidation treatment in an alkaline solution of this coated powder are suggested. 

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