The Nickel-Metal Hydride Battery NiMH

The anode of a current NiMH battery on the market has the typical ABs structure, but both A and B do not represent pure metals but rather some nonstoichiometric combination of metals of the same group as La and Ni, respectively. A typical formulation can be written as [La(5.7)Ce(8.0)Pr(0.8)Nd(2.3)] [Ni(59.2)Co(12.2)Mn(6.8)Al(5.0)], where the numbers represent the relative atom% concentrations of each element. Adding up the numbers this corresponds to A(16.8)B(83.2), which could also be written as AB4.gs, very close to the LaNis discussed above. 

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So good were some of these alloys that their ability to absorb and redischarge H when coupled to some inert counter-cathode (not yet a battery ) was equivalent to 400 W hr kg"1. Thus was bom the idea of the nickel-metal hydride battery, NiMH as it is written (where M is an alloy of V, Zr, Ti, etc.), one of the leading new batteries of the later 1990s. 

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