As part of ongoing research to examine performance degradation caused by cycling, Cadex tested a large volume of portable batteries for wireless communication devices. The population consists of nickel-cadmium, nickel-metal-hydride and lithium‑ion. The batteries were prepared by applying an initial charge, followed by a regime of full discharge/charge cycles.
The following section describes nickel-based batteries, and we begin with nickel-cadmium (NiCd), an older chemistry for which extensive data is available. Much of these characteristics also apply to nickel-metal-hydride (NiMH), as these two systems are close cousins. The toxicity of NiCd is limiting this solid and robust battery to specialty applications.
Pioneer work with the lithium battery began in 1912 under G.N. Lewis, but it was not until the early 1970s that the first non-rechargeable lithium batteries became commercially available. Attempts to develop rechargeable lithium batteries followed in the 1980s but the endeavor failed because of instabilities in the metallic lithium used as anode material.
Lithium is the lightest of all metals, has the greatest electrochemical potential and provides the largest specific energy per weight.
Lead acid batteries continue to hold a leading position, especially in wheeled mobility and stationary applications. This strong market appeal entices manufacturers to explore ways to make the batteries better. Improvements have been made and some claims are so promising that one questions the trustworthiness. It is no secret that researchers prefer publishing the positive attributes while keeping the negatives under wraps. The following information on lead acid developments was obtained from available printed resources at the time of writing.