Nickel-cadmium battery cycling life

Stationary battery (cell) — Rechargeable -> batteries designed to be located at a fixed place. Stationary batteries are used mainly for uninterruptible power supplies (UPS) and standby applications. These cells are usually designed for high reliability and very long -> cycle life under shallow depth of discharge (DOD) conditions. The common chemical systems utilized for the production of stationary batteries are the -> lead-acid and -> nickel-cadmium batteries. Less common, and more futuristic is the - sodium-sulfur battery designed for KW and... 

A metal hydride battery similar to the nickel-cadmium battery has been developed by Sharp corporation. The battery is shaped in the form of a button of 20 mm diameter and can give 1.2 V. The anode in the battery is made of La-Ni-Sn alloy hydride, and the cathode is nickel oxide. Potassium hydroxide solution in polyamide-resin is the electrolyte. The battery exhibits high energy density (i.e.) 1.5 to 2.0 times that of the Ni-Cd battery, good cycling life and superior low temperature behaviours. 

Nickel-metal hydride batteries have higher energy densities as compared to nickel-cadmium batteries, but at the expense of reduced cycle life [29],... 

When attention focused on pure-electric vehicles (EVs) at the beginning of the 1990s, it was clear that the VRLA battery could not deliver the desired service-life. Within a decade, however, the industry, supported by the extensive research programme mounted by the Advanced Lead-Acid Battery Consortium (ALABC), had made the necessary investment in research and development to achieve a ten-fold increase in deep-cycle life. The VRLA battery was then able to compete with alternative chemistries (e.g., nickel-cadmium, nickel-metal-hydride, lithium-ion) as an acceptable power source for EVs. 

Cornu and Eloy 1995, Nickel Cadmium Batteries Life Cycle Analysis in the Electric Vehicles Application, The Seventh International Seminar on Battery Waste Management, Deerfield Beach, Florida, November 8, 1995. 

Geomet Technologies 1993, Nickel-Cadmium Batteries for Electric Vehicles - Life Cycle Environmental and Safety Issues, Final Report No IE-2629 prepared for the Eleetrie Power Research Institute (EPRI), December 1993. 

Morrow 1998, The Importance of Recycling and Performance to Life Cycle Analyses of Nickel Cadmium Batteries, S International Nickel-Cadmium Battery Conference, Prague, Czech Republic, September 20-21,1998. 

The SAFT AB recycling plant at Oskarshamn/Sweden is fully integrated in the manufacturing plant for industrial nickel-cadmium batteries. It demonstrates the commitment of the major european NiCd battery producer to control the life-cycle of the products introduced on the market. Process development started in 1978 and the operation reached industrial scale in 1986 (Figure 6). 

The silver-cadmium (cadmium/silver oxide) battery has significantly longer cycle life and better low-temperature performance than the silver-zinc battery but is inferior in these characteristics compared with the nickel-cadmium battery. Its energy density, too, is between that of the nickel-cadmium and the silver-zinc batteries. The battery is also very expensive, using two of the more costly electrode materials. As a result, the silver-cadmium battery was never developed commercially but is used in special applications, such as nonmagnetic batteries and space applications. Other silver battery systems, such as silver-hydrogen and silver-metal hydride couples, have been the subject of development activity but have not reached commercial viability. 

Nickel-Zinc Batteries. The nickel-zinc (zinc/nickel oxide) battery has characteristics midway between those of the nickel-cadmium and the silver-zinc battery systems. Its energy density is about twice that of the nickel-cadmium battery, but the cycle life previously has been limited due to the tendency of the zinc electrode toward shape change which reduces capacity and dendrite formations, which cause internal short-circuiting. 

Of the conventional secondary systems, the nickel-iron and the vented pocket-type nickel-cadmium batteries are best with regard to cycle life and total lifetime. The nickel-hydrogen battery developed mainly for aerospace applications, has demonstrated very long cycle life under shallow depth of discharge. The lead-acid batteries do not match the performance of the best alkaline batteries. The pasted cells have the shortest life of the lead-acid cells the best cycle life is obtained with the tubular design, and the Plante design has the best lifetime. 

Long service life Over 500 cycles of discharge or up to 5 to 7 years of standby power are common to sealed nickel-cadmium batteries. 

FIGURE 28.21 Cycle life of sealed nickel-cadmium batteries at 20°C. Cycle conditions charge—O.IC X 11 h discharge—0.7C X 1 h. Capacity-measuring conditions charge— O.IC X 16 h discharge—0.2C, end voltage—1 V. 

FIGURE 28.22 Cycle life of sealed nickel-cadmium batteries at shallow discharge. 

The useful life of a nickel-cadmium battery can be measured either in terms of the number of cycles before failure or in units of time. It is virtually impossible to know all the detailed information necessary to make any kind of accurate prediction of battery life in a given application. The best that can be provided is an estimate based on laboratory test data and field experience or extrapolation of accelerated test data. 

In applications with permanent maintenance charge, the life of a battery is expressed as the multiple of Cs Ah of overcharge or as hours of operation, and the failure rate as failures per operating hour. As an example. Figure 4.5 shows the estimated cycling life at 20°C as a function of discharge for SAJT sealed nickel-cadmium batteries. 

Figure 4.5 Estimated life cycle at 20°C as a function of discharge (SAFT sealed nickel-cadmium batteries) (Courtesy of SAFT)...

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