(20 points) One type of Li-ion battery includes a graphite negative electrode and manganese dioxide spinel positive electrode, described by the following reactions (written in the discharge direction): LixC6xLi++xe+C6xLi++xe+Mn2O4LixMn2O4(negative)(positive) The electrolyte consists of an organic solvent that contains a binary LiPF6 lithium salt. Assume a onedimensional cell with the cathode located at x=0 and the anode located at x=L. The following properties are known: DLi+=1.81010m2s1,DPF6=2.61010m2s1,t+=0.4. For now, we assume that the electrodes have flat surfaces, and that they are separated by an electrolyte-containing separator that is 25m thick. The initial concentration of LiPF6 in the electrolyte is 1.0M. The parameters given in the question are for transport in the separator. a. In which direction does the current in the solution flow during charge? Is this positive or negative relative to the x-direction? b. Where is the concentration highest, at x=0 or x=L ? c. What is the concentration difference across the separator if a cell with a 2cm5cm electrode is operated at a total current of 10mA ? Is this difference significant? d. Briefly describe how you would calculate the cell potential for a constant current discharge of this cell if the current is known and the concentration variation is known. The potential would be measured between the current collectors of the cathode and anode during discharge. You do not need to include all the equations that you would use. The important thing is that you know and are able to identify the factors that contribute to the measured cell potential, and that you know the process by which you might determine their values