Ni-MH rechargeable battery

T. Yoshida, H. Ono, and R. Shirai, Recycling of Used Ni-MH Rechargeable Batteries, Proceedings of the Third International Symposium on Recycling of Metals and Engineered Materials, pp. 145-152,1995. 

A series of mischmetal nickel alloys are known as typical hydrogen-absorbing materials (see Chapter 6.3) and are used as the negative electrode in Ni-MH rechargeable batteries (see Chapter 8.4). By the fluorination treatment of mischmetal nickel alloys the electric conductivity is significantly improved by the replacement of La-oxide and La-hydroxide layers on the Ni-emiched Lap2 surface. The layer was also found to protect the surface firom KOH alkaline solution as electrolyte and to improve the long-term durability. 

Figure 1.6 Progressive optimizing steps for La-Nij alloy—based sealed Ni-MH rechargeable batteries. (Mm Mischmetal.)...

Since 2001, Ni-Cd and Ni-MH rechargeable batteries have kept at an almost-constant market share. But since 2005, among the nonaqueous batteries, lithium-based batteries have been receiving the most attention. Particularly, laminated Li batteries are in great demand for commercial applications and increasingly are being sold in the market. Characteristics of some nonaqueous batteries best suited for commercial applications are shown in Table 1.7. 

The car comes with a 330 V, sealed nickel-metal-hydride (Ni-MH) rechargeable battery pack. 

Figure 4.4 Prismatic version of Ni-MH rechargeable battery pack and its cell voltage as a function of battery capacity (Ah) at various charge current levels (V).

REEs are widely used in various components of the EVs and HEVs. In particular, the use of REEs in Ni-MH rechargeable battery packs, catalytic converters, and hybrid electric motor generators has led to significant improvements in efficiency and reliability and has considerably reduced the weight and size of the components involved. The use of REEs in various EV and HEV components is identified in Table 4.12. 

Figure 5.5 Typical storage characteristics of Ni-MH rechargeable batteries at various temperatures. (Courtesy of Duracell.)...

Our preliminary review of sealed Ni-MH rechargeable batteries with moderate capacity indicates that charge is a critical step in determining battery performance and overall life of Ni-MH batteries because of their sensitivity to charging conditions. Performance highlights of Ni-MH batteries are summarized as follows ... 

Ni-MH rechargeable batteries will suffer in longevity and performance if repeatedly overcharged. 

Ni-Cd and Ni-MH rechargeable batteries do suffer from memory effects. 

Besides the application of solid hydrogen storage, MH alloys also play a very important role in nickel/metal hydride (Ni/MH) rechargeable battery as the negative electrode. The chemical reaction during charge/ discharge is ... 

High average output voltage ( 3.6 V) This is three times of that for the Ni-Cd or Ni-MH rechargeable batteries. 

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