Modeling discharge and charge characteristics of nickel–metal hydride batteries

Advances in Electrochemical Models for Predicting the Cycling Performance of Traction Batteries: Experimental Study on Ni-MH and Simulation

“…Each cell was characterised in terms of capacity and physical parameters such as electrode and separator nature, thicknesses and electrolyte concentration to provide related parameters for the simulation and try to duplicate exactly the runs with the model. However, other microscopic geometrical parameters were selected according to the literature [13,22]. Under this hypothesis, nickel oxide electrode consists of composite cylindrical needles with a substrate inside.…”

“…A main simplification of this approach (diffusion length approach) consists in neglecting the diffusion along the y-directions, except for a localized concentration discontinuity between the bulk of the fictitious particle and its interface with the electrolyte. Computationally, the model thus reduces to a one-dimensional (1D) domain [13].…”

“…The latter is variously calculated in the literature, and corresponds to 1/6 for LaNi 5 H 6 [13]. In …”

“…To take into account in a lumped-parameter way the diffusion in the solid phase, the concentrations calculated with Equations (13)(14) can be distinguished from the concentrations used in the Butler-Volmer equations. Inspired by the diffusion length approach where the diffusion rate is constant along a diffusion length l se across the characteristic geometry [13], the rules to differentiate the average concentration from the interfacial concentration are: (15) (16) where D h is the diffusion coefficient of hydrogen, c i is the average concentration of species i and c i with bar is the interfacial concentration, which is also used in the Butler-Volmer Equations (5) to (8).…”

“…They constitute a very promising approach with regards to other methods since SoC is an internal parameter of these physical models. Sophisticated and simpler models were presented as valuable physical models to predict the SoC and other performance of both Ni-MH cells [12][13][14][15][16] and lithium ion cells [17][18][19][20]. However, the computational time needed to solve rigorous electrochemical battery models for online applications requires to develop a simplified physics-based battery model with specific efforts to account for the diffusion phenomena.…”