One way to enhance the thermal performance of the Li-ion batteries is embedding microgrooves inside the porous electrodes and flowing the electrolyte through these microgrooves. Heat transfer from the battery can be enhanced by having both convection and conduction heat transfers inside the electrodes, instead of conduction heat transfer alone. A two-dimensional thermal lattice Boltzmann method (LBM) was employed to predict electrolyte flow, heat transfer, and internal heat generation inside the positive porous electrode. Size and number of the microgrooves and the electrolyte flow velocity inside them were investigated, and it was found that embedding microgrooves inside the porous electrode improved the thermal performance of the Li-ion battery by keeping the electrode in lower temperatures and improving its temperature uniformity. Furthermore, increasing the electrolyte flow velocity as well as increasing the number of microgrooves (in a constant ratio between the total size of the microgrooves to the size of the porous electrode) kept the porous electrode in lower temperatures and enhanced temperature uniformity.