Panasonic’s and Sanyo’s enduring Nickel-hydrogen Battery for hybrid vehicles

[2009, June. 17]

Abstract

Nickel-hydrogen batteries became common as alternatives for nickel-cadmium batteries within electric calculators, portable music players, or digital cameras because they have larger capacity and are more environmentally-friendly (or, they don’t have cadmium in them) than nickel-cadmium batteries, which had been common until then. After that, lithium-ion batteries began to replace nickel-hydrogen batteries and the delivery of nickel-hydrogen batteries decreased significantly. However, nickel-hydrogen batteries have been attracting lots of attention again thanks to Toyota’s and Honda’s placing on the market. To keep the prices of vehicles in affordable range, lithium-ion batteries are extremely expensive as secondary batteries for hybrid vehicles. On the contrary, because it is possible to keep the prices of the cars with nickel-hydrogen batteries, the delivery of them is increasing. However, things in R&D have been changing, as the purposes of batteries varied (Fig 1). Toshiba, applied for patents on NiMH most aggressively among the major manufacturers in 1990s, has hardly been applying for patent since 2000. Panasonic and Sanyo Electric have been applying, following Toshiba, but were on a plateau for a while. However, Panasonic has been applying for patent since 2006 aggressively in the field of extension of battery life or the field of improvement of service capacity, and Sanyo Electric has also been doing so since 2004 (Fig 2). For example, in the publications of application since 2006, these phrases are found frequently: “to improve battery characteristic without reducing the thermal tolerance characteristic”, “to shorten charge time without reducing the cycle life”, “to prevent deterioration due to the thermal storage by the center”, “rapid charge”, “powerful discharge”, etc. These are extension of life span, stabilization, or improvement of charge-discharge cycle, as well as the technical problems for adjusting to the hard environment in hybrid vehicles. Sanyo Electric, on the other hand, additionally raised other technical problems on endurance and control such as “to apply for wide range of heat” or “to accurately judge the life of the battery”.


Thus, the development of nickel-hydrogen battery has gone into another phase because of the application for the new field, hybrid vehicles, and the major players have surely been developing the existing technology to a higher level.

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