You might consider the Li ions flow (only) in the Li-electrolyte as a fluid, having a constant  Li ions' density. The other parts, interfaces[1], and electrode[3-4] materials are more complex[1-4] than a classical fluid.

1. Mechanical stresses at the cathode–electrolyte interface in lithium-ion batteries https://www.cambridge.org/core/journals/journal-of-materials-research/article/div-classtitlemechanical-stresses-at-the-cathodeelectrolyte-interface-in-lithium-ion-batteriesdiv/97735B0D1B787BD26643ACD913A5EF67

2. Chemical Diffusion Coefficient   http://jrgreer.caltech.edu/content/teaching/MS133Files/Notes/Lect7MS133JRG.pdf

3. Determination of the chemical diffusion coefficient of lithium in LiFePO4 http://ac.els-cdn.com/S0167273802001340/1-s2.0-S0167273802001340-main.pdf?_tid=7b195c18-edf8-11e6-aee4-00000aacb35e&acdnat=1486556395_e0bb9ba47b25d28a40349e1ce37ff190

4. Determination of lithium diffusion coefficient in LiFePO4 electrode by galvanostatic and potentiostatic intermittent titration techniques http://ac.els-cdn.com/S0013468610000289/1-s2.0-S0013468610000289-main.pdf?_tid=a6becf1a-edf8-11e6-818c-00000aacb35e&acdnat=1486556468_1cb9c6dba79f802f59b113197de83ad3

Respected sir @Ioannis Samaras

I have gone through your provided literature, while considering these and up to my knowledge as Physicist,  I am taking the motion of Li ions in electrodes a complex (no simple classical fluid flow) phenomenon depending upon vacancies of Li ions  Li concentration [1,2] , surface potential gradient [3]  and nature of cation/oxidation potential  as well, it use different migration Path like O-T-O migration (1)  but, its not violating the basic Fluid Flow definition given in Fluid Mechenics by J.F Dougles 5th edition i.e. "a substance that deforms continuously (continues to flow) under shearing force how small it may be" so these moving ions flows anyways (both charge and discharge with respective Q-rates), we may consider the opposing factors as viscose terms or we may consider it as non-Newtonian flow , or exactly the electron gas and Fermi Liquid as given in the trailing answer, that is what I want to discuss Sir.

I will wait for your comment sir.

I highly endorse the convincing explanation provided by Respected Sir Artur Braun in the pure Physics framework, sir thank you so much for your comment.  

(1) http://pubs.rsc.org/en/Content/ArticleLanding/2012/CP/c2cp42154b#!divAbstract

(2)http://journals.aps.org/prb/abstract/10.1103/PhysRevB.81.104304

(3) http://pubs.acs.org/doi/abs/10.1021/jp509232m

OK @Arslan Ullah, you might consider the Li ions flow as non - "classical" fluid, proposed by Prof. Artur Braun. In this case, the error[1] values might be a useful tool for a better focus in our understanding on the Li ions flow[2].

1. The differences between Exper. data and your flow Model.

2. You might start with a case of Lithium manganese oxide system. LiFePO4 is a more difficult case.

Respected Sir @Ioannis Ssmaras, @Artur Braun,Thank you so much for your attention . I am still not clear how to include viscosity terms in this case, as there are no fluid layers here. so I am  still studying about this and I will reply soon.

Which aspect of fluid are you considering?  The inertial aspect seems irrelevant.  Electrostatic forces generally dominate such systems.  Sometimes when people talk of "fluid" they refer to the highly correlated motion as in strongly interacting quantum gases, even though hydro only applies in a very limited way to them.