We consider the mathematical treatment of a system of nonlinear partial differential equations based on a model, proposed in 1972 by J. Newman, in which the coupling between the Lithium concentration, the phase potentials and temperature in the electrodes and the electrolyte of a Lithium battery cell is considered. After introducing some functional spaces well-adapted to our framework we obtain some rigorous results showing the well-posedness of the system, first for some short time and then, by considering some hypothesis on the nonlinearities, globally in time. As far as we know, this is the first result in the literature proving existence in time of the full Newman model, which follows previous results by the third author in 2016 regarding a simplified case. Keywords: Lithium-ion battery cell, multiscale mathematical model, Green operators, fixed point theory, Browder-Minty existence results, super and sub solutions 2010 MSC: 35M10, 35Q60, 35C15, 35B50, 35B60• The electric potential φ s = φ s (x, t) in the electrodes.• The electric potential measured by a reference Lithium electrode in the electrolyte, ϕ e = ϕ e (x, t).• The temperature T (t) in the cell.The system of equations is given by (5)-(9) below.