Li-ion batteries used in automobiles typically use a LiMn2O4 cathode in place of the LiCoO2 cathode found in most Li-ion batteries. (b) Which material has a higher percentage of lithium? Does this help to explain why batteries made with LiMn2O4 cathodes deliver less power on discharging?

Video transcript

Welcome back everyone in this example, we have the cathode lithium manganese oxide and lithium ion batteries can be replaced by lithium iron phosphate. The use of lithium iron phosphate has received widespread market approval because of its low cost it's nontoxic and irons natural abundance determine which material has a higher percentage of lithium and identify which cathode will deliver greater power upon discharging. So what we want to first calculate is the percent mass of lithium in each of our compounds. So beginning with our lithium in lithium manganese oxide, we're going to begin by taking note of the molar mass of lithium, Which from our periodic table, we see as the value of 6.941 g per mole. And then we want to make note of our mass molar mass of lithium manganese oxide, which we can see from our periodic table for every atom in this molecule is a value of 180. g per mole. And so for our percent of lithium in lithium manganese oxide, we're going to take our 6.941 g of lithium. And we're going to divide by our molar mass of lithium manganese oxide. 1 80.817 g. And now we want to multiply by 100%. And so this is going to give us a result of 3.839% of lithium in lithium manganese oxide. Following the same process, we're going to calculate the percent of lithium in our second compound lithium iron phosphate. And we're going to take again the molar mass of lithium 6. g of lithium Divided by the molar mass of lithium iron phosphate. Which we can determine based on every atom in this molecule from our periodic table is equal to a value of 157.76 g per mole. So in our denominator will plug in 157.76g. And then we're going to multiply by 100%. We're going to cancel our units of g and this is going to yield a result Of 4.400%. Now we want to recall that our specific energy density refers to the amount of energy of our battery stored per unit mass. We also want to recall that our lithium ion battery. Sorry. This says battery here produces power by the migration of our cat ion so of lithium Arkady on here. And it doesn't have to be all of this caddy on. It can be a good amount of this lithium caddy on that will be migrating during a full charge. And with these facts in mind, we should recognize that the greater our percentage of lithium in our compound will correspond to a greater amount of our lithium caddy on migrating. And so therefore we have an increase of greater power produced by our battery. Sorry, This says power. And so looking at our results from above, we can see that we have a greater percent of lithium in our lithium iron phosphate. So we have a greater percent of lithium and we would say thus our lithium iron phosphate produces greater power upon charging this battery. And our final answer is going to be lithium iron phosphate, which has a higher percentage of our lithium as we determined. And so therefore it produces a greater power upon charging. So it's highlighted in yellow, completes this example as our final answer. I hope everything I reviewed was clear. If you have any questions, leave them down below and I'll see everyone in the next practice video.