Integrals as boundary condition

Hi all,

I'm building a Newman's battery model in COMSOL using PDE (coefficient from PDE). Since it is a 2D model, at the surface of the current collector, I'd like to impose the integration condition in below :

So at the surface, the total current is constant, yet its local flux could be non-uniform.

But I counldn't find any option in the PDE physic that allows me to do this.

Is there any solution for me ?

Thank you for your help,