An alternative to lithium-ion batteries–silver-zinc batteries–could add several hours to the time that laptops can run between charges, while at the same time avoiding the safety issues that have resulted in the recent massive recalls of laptop batteries made by Sony, according to Zinc Matrix Power in Camarillo, CA.
The company, which received an innovation award from Intel last month for its new battery, has now demonstrated the silver-zinc technology in a laptop. Zinc Matrix plans to begin distributing test batteries to manufacturers early next year, focusing on applications in laptops and cell phones.
In part, the gains in laptop runtimes would come because the silver-zinc batteries can store about 25 percent more energy in the same space, a result of both the chemistry and a more space-efficient flat shape, compared with cylindrical lithium-ion cells inside laptop battery packs, says Ross Dueber, president and CEO of Zinc Matrix Power. What’s more, because silver-zinc batteries use a safer chemistry than most lithium-ion batteries, manufacturers could use larger batteries packs in laptops.
Silver-zinc rechargeable batteries are not new–for example, they’ve been used by the Navy in submarines for years. But they’ve been plagued by high costs due to the use of silver, and by a short lifespan because they can be charged and discharged for only a relatively few cycles, and so have to be replaced more frequently than other types of batteries.
Dueber says the company plans to keep down the costs with a recycling program that will allow it to reuse the silver and zinc. And it has extended the charging cycle-life to hundreds of cycles–similar to many lithium-ion batteries. One of the reasons for the previously low cycle-life is that, as the batteries charge and recharge, zinc in the cell undergoes physical changes that lead to decreasing cell capacities. The company addressed this problem by embedding zinc granules within a conductive polymer.
The safety of the batteries in part results from the use of a nonflammable electrolyte. “It is an inherently safe technology in comparison to lithium ion,” Dueber says. “The fundamental difference is we do not use a highly flammable electrolyte, like lithium ion does. If you have an internal short circuit, which has recently plagued lithium ion, it does not have the possibility of bursting into flames and exploding.”