Mercury-free Silver Oxide Battery Technology---Stepping stone to a mercury-free alkaline button battery

The development of a mercury-free alkaline button battery was an even greater challenge, and was initially regarded as impossible in practical terms. Unlike silver oxide batteries, alkaline button batteries contain no substances capable of absorbing hydrogen gas. However, alkaline button batteries are cheaper than silver oxide batteries. Because they are widely used in portable consumer electronics products such as game consoles, toys and other items, they are frequently handled by both adults and children. As Sony began to develop a mercury-free alkaline button battery, its first priority was to ensure safety.

In a silver oxide battery, any hydrogen gas produced is absorbed by the silver oxide. Sony engineers believed it would be possible to develop a safe, mercury-free alkaline button battery if they could find the proper material to perform the same role. This led to intensive research and development efforts focusing on materials with a high capacity to absorb hydrogen gas. By adding a hydrogen-absorbing material to the cathode, and combining this with the three unique technologies developed for the mercury-free silver oxide battery, Sony succeeded in commercializing a mercury-free alkaline button battery that matched or surpassed batteries containing mercury in terms of both safety and performance.

Future Challenges

Sony sells around 300 million^*1 alkaline button batteries and silver oxide batteries. The development of mercury-free batteries has the potential to reduce the amount of mercury used each year in these two types of batteries by approximately 470kg, or enough to fill approximately 68 clear plastic 500ml beverage bottles. Sony is dedicated to reducing its carbon footprint via ongoing technological advances. Sony is also dedicated to eliminating all hazardous substances throughout the company's various processes.

Sony's Path to the Development of Mercury-free Batteries