Cell and Battery Designs

The investigations of various types of carbon-based catalysts allow suitable air electrodes to be developed for use in the large variety of metalair cells and batteries designed in this laboratory. 

The performance of the experimental vehicles was impressive and confirmed the technical feasibility of the sodium/sulphur battery for traction applications. At the same time it was recognised that for commercial viability it would be necessary to improve the volumetric energy density of the battery and to custom-design it for a particular vehicle, as well as extending the lifespan and reliability of the cells. These developments involve problems of cell and battery design and further work in Britain has been directed towards these goals. 

The final, and major constraint of the designer is that the cell and battery designs which evolve shall be amenable to mass production techniques at realistic costs. This is too extensive a topic to discuss here suffice it to say that each proposed material of construction and component design must be reviewed critically in the light of this criterion. The size of the operation can be gauged by considering a modest market for 60,000 urban delivery vans with a battery life of 3 years. The annual requirement would then be for 20,000 traction batteries containing, say, 15-20 million cells. If a production line assembled cells at the rate of two per minute and operated three shifts, all the year, it would still require 20 such production lines to manufacture this number of cells. The need for simplicity and automation is evident. 

Puglia F, Cohen S, HaU J, YevoU V (2005) Very Large Lithium Ion Cell and Battery Designs. The 5th International Advanced Automotive Ultracapacitor Conference (AABC-05) Proceedings. Honolulu, Hawaii... 

Lawrence HT, Albert HZ (1996) Electrolyte management considerations in modem nickel/hydrogen and nickel/cadmium cell and battery designs. J Power Sources 63 53-61... 

It should be noted, as discussed in detail in Chaps. 1, 3 and 6, that most of these types of data and comparisons are based on the performance characteristics of single-cell batteries and are necessarily approximations, with each system presented under favorable discharge conditions. The specific performance of a battery system is very dependent on the cell and battery design and all of the specific conditions of use and discharge of the battery. 

Elevated temperatures will increase the rate of the self-discharge reaction dramatically. The capacity loss after 28 days of storage at 54°C, averaged about 3%. Storage life at high temperatures can be optimized through tradeoffs between other performance parameters and choice of cell and battery design components. 

Various types of cell and battery design and construction can be used in the nickel-zinc battery system. Cells have been built in both prismatic and cylindrical designs and both vented and sealed designs. However, most current commercial applications require the use of a sealed, maintenance-free design. A typical sealed prismatic battery is shown in Fig. 31.7. This type of construction can be used for a wide range of cell sizes and is particularly suited to larger capacity batteries (e.g. greater than 10 Ampere-hours). 

Thermal characteristics of cells and batteries are one of the most important aspects of safe cell and battery design. Individual materials and complete battery modules should be characterized. 

A variety of primary zinc-air cell and batteries are designed with capacity ranging from 100 Ah to 3300 Ah, operating at nominal currents from 2 to 40A at temperatures in the range +40 -t- -40°C. Mechanically rechargeable zinc-air cell are also developed and tested in experimental electric cars and scooters. 

Ragone plots reveal some characteristic differences of fuel cells and batteries. To put the matter succinctly, batteries are known for their power and fuel cells for their energy, both per unit of weight. Discuss these characteristics as the basis for hybrid designs in the powering of automobiles. (Bockris)... 

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... 

With respect to the present state of battery development, it can be simply stated that most of the current work is being carried out at the laboratory level and that it is concentrated towards acquiring the necessary technology for the design and construction of practical cells and battery systems. However, there have been several successful attempts to build hermetically sealed cells and to assemble a large number of these cells into batteries. Four notable examples are discussed below. 

Although the cited examples are far from being prototypes of production devices, they do validate the feasibility of fully packaged sodium-sulfur cells and provide a measure of projected performance. It seems that sufficient information is now available to permit researchers to speculate on the design of large cells and battery systems and to project the performance of such devices on the basis of anticipated technology. 

Abuse tolerance in lithium-ion cells is critical to public safety, and a number of screening tests for lithium-ion cells and batteries have been devised. Battery developers and users then test cells and batteries to screen for tolerance with respect to the given abuse, and then design cells and batteries with improved abuse tolerance. 

Once the principles of operating in a molten salt environment have been grasped, suitable extrapolations or interpolations of materials requirements and cell and equipment designs can be made between different systems. In bringing a molten salt process into commercial operation, unique materials problems requiring special solutions often limit its progress, but practically never prevent it. Thus, if a desired result may not be achieved for theoretical reasons in any alternative electrolyte, because of electrochemical instability, for example, then initial development costs and difficulties become inconsequential. Such has been the case with thermal batteries, " sodium-sulfur batteries, molten fluoride nuclear reactors, and molten carbonate fuel... 

This chapter describes specific satellite applications and different cells and battery concepts and designs proposed by the different suppliers. The associated qualification requirements are also discussed in order to demonstrate the specificity of the space use. 

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