Comparative assessment of button cells using a normalized index for potential pollution by heavy metals

Area of Science:

• Environmental Science
• Materials Science
• Analytical Chemistry

Background:

• Inefficient battery collection and recycling lead to landfilling and incineration of household batteries.
• Improperly discarded button cells release toxic heavy metals, posing risks to human health and ecosystems through air, soil, and water pollution.

Purpose of the Study:

• To analyze and compare the polluting potential of various button cell batteries available on the retail market.
• To introduce an energy-normalized index (Weighted Potential Pollution Index - WPPI) for assessing battery pollution.

Main Methods:

• Chemical analysis of 19 elements and energy density measurements for 64 button cell batteries across four common technologies (alkaline, zinc-air, silver oxide, lithium) and multiple brands.
• Calculation of the Weighted Potential Pollution Index (WPPI) to normalize pollution potential by energy output.

Main Results:

• Significant variations in chemical composition and energy density were observed between different button cell technologies and brands.
• The WPPI revealed substantial differences in potential pollution, indicating that selecting less polluting options can significantly reduce environmental impact (3-53% reduction depending on technology).

Conclusions:

• Consumers and industry can mitigate the environmental risks of button cell batteries by choosing options with more favorable WPPI scores.
• The WPPI serves as a valuable tool for comparative assessment, guiding the selection of batteries with reduced environmental impact from improper disposal.