Primary batteries energy density

Globe Union, A Program to Develop a High Energy Density Primary Battery with a minimum of 200 w att hours per pound of total battery w eight. Final Report No. NASA CR-72364, Contract No. NAS3-6015 (1967). 

Figure 4 shows a comparison of practical energy density and specific energy of primary batteries. Two groups can be distinguished the zinc-based and lithium-based systems. 

For the feature widescale use of high energy-density primary and secondary batteries it is important to develop methods for the determination of the state of charge of the battery. Continuous and reliable monitoring of the state of charge of the batteries in an electric car, for example, would seem to be an essential requirement for their large scale acceptance. 

T. Atwater, R. Putt, D. Bouland, and B. Bragg, High-Energy Density Primary Zinc/Air Battery Characterization, Proc. 36th Power Sources Covf., Cherry Hill, NJ, 1994. 

Figure 1. Conceptual product definitions of enzyme-based biofuel cells as they are compared in their specific energy and energy density to the existing primary battery technology. Based on Figure 2 of ref 15. Reproduced with permission. Copyright 1999 The Electrochemical Society, Inc.

Figure 1 Juxtaposes the energy fields of these three potential product definitions with that of conventional primary battery technology. The data on the energy densities for the battery product definitions were adopted from a recent technology review. The expected energy performance figures for biofuel cells...

In considering the selection of anodes for high energy density (HED) storage (or secondary) batteries (SB), we note that there are some 19 metals whose free-energy density (TED) of reaction with oxidants such as O2, Cl2, and F2 are higher than those of Zn with the same oxidants. Most of these metals react violently with water. The remainder are passivated by water. Therefore other electrolytes must be considered for these metals, based on non-aqueous, molten salt, or solid-state ionic conductors. Much experimental work has been carried out during the last two decades on primary and secondary batteries based on anhydrous electrolytes, aimed at utilization of the active metals. 

Despite the availability of several articles and patents on nonaqueous secondary batteries (42-56), there is little hard evidence that these batteries are approaching the commercial stage. However, the fact known long ago that light metals of high energy density can be electrodeposited from their nonaqueous solutions at ambient temperatures (3,4,21), and the successful completion of several primary nonaqueous batteries to the commercial stage, has raised hopes of the possible construction of secondary HED batteries based on the same solutions. So far. 

The aims of the battery manufacturer have remained much the same since the beginnings of commercial exploitation. For small primary systems, the main goal is to provide higher energy and power density coupled with long shelf life and low cost. However, primary batteries are always an expensive... 

The primary objective of miniature battery design is to maximize the energy density in a small container. A compromise must be reached, however, since volumetric energy density decreases as cell volume decreases and the dead volume due to containers, seals, etc. becomes increasingly significant. A plot of energy density as a function of total volume is given in Fig. 3.28 for the zinc-mercuric oxide and zinc-silver oxide systems. 

Solvents that meet all or most of the criteria are propylene carbonate, dimethyl sulfoxide, 4-butyrolactone, acetonitrile, sulfur dioxide, thionyl chloride, and phosphorus oxychloride. Certain other solvents, with fairly low s values, such as tetrahydrofuran, dimethoxyethane, and 1,3-oxolane are used in conjunction with a high s solvent, in order to reduce the viscosity without impairing excessively the other desirable properties of the co-solvent. All these solvents are on the List, with properties shown in the tables mentioned. Commercial implementation of such batteries has been highly successful, with energy densities of primary dischargeable batteries of 0.3 W h g 1 or 0.5 W h cm 3 and a self discharge rate of < 2% per year of the open-circuit battery being achieved. 

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