NiMH batteries: material intensity calculations by element

* According to the source, an n/p ratio of 1.8 is assumed for the high material content case, which represents a likely value for current-generation technology. For low material content, an n/p ratio of 1.2 is assumed, which represents a lower value that is technically feasible by the medium term. The n/p ratio is the assumed ratio of negative to positive electrode capacity.

Estimates for calculating positive electrode capacity were from Toyota (2009) and EERE (2009). Estimates for the n/p ratio and weight ratio of negative electrode alloy were provided by EERE (2010). Alloy composition is based on Linden’s Handbook of Batteries (Reddy 2011).

According to the source, the material intensity of elements used in NiMH batteries was calculated based on several assumptions about capacity and chemistry (i.e., anode and cathode composition) for a battery with a power rating and cell voltage equivalent to the battery used in a third-generation Toyota Prius. NiMH material intensity for batteries used by other manufacturers would likely vary with battery performance specifications and the composition of the battery alloy.