**6.2 Efficient lumped model for distributed parameters systems**

For non specialists, the "Warburg impedance" may look a very esoteric electrochemical topic. We introduce an analogy with a subject quite trivial for electronic engineers, capacitive transmission lines. Approximation of such distributed parameter device by lumped RC network has been the subject of a lot of papers (Kuhn et al., 2006 and Mauracher et al., 1997). We propose an efficient approximation with RC cells in geometric progression.

### **6.3 Possible extensions**

We consider that our analysis constitutes an important contribution to the understanding of battery operation, in particular for electronic engineers. It opens the way for inclusion in efficient control of complex systems, either in the field of power managing or signal processing.
