I am trying to find the current transferred to the anode and cathode of a Lithium Ion Battery at different voltages. I know the temperature (approximately) of the battery, the battery's starting voltage, the voltage at 30sec intervals of a constant power discharge (from which current can be deduced), the dimensions of the battery and the initial amount of charge in the battery. What could I do to find this current transfer?
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$\begingroup$ Use ammeter instead? $\endgroup$ – Mithoron Sep 14 '18 at 20:55
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$\begingroup$ Do you mean "current" (e.g. mA) or "charge transfer" (e.g. mAH)? $\endgroup$ – DrMoishe Pippik Sep 14 '18 at 21:53
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$\begingroup$ Current so it would be mA and can't really use an ammeter because that would require me opening up the battery which is kind of hard at this stage. $\endgroup$ – mfarrington Sep 14 '18 at 22:22
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Power is the energy transferred per unit time ($\frac{J}{s}$) and is determined by the potential drop (V) and the current (I) at a given point in time as $P = IV$ so to get the current, solve for $I=\frac{P}{V}$. This gives you the current at a given point in time.
Your question has a few points that might be worth addressing. As Dr Moishe Pippik commented, "current transferred" is a little confusing, either instantaneous current ($I$), or total charge transferred ($Q$), which is the current integrated over time: $\sum_{t} I(t)\Delta t$ in your case. So if what you really want is the total charge transferred, you would have $Q = \sum_{t}\frac{P\Delta t}{V(t)} $. Strictly speaking you should exclude t=0 point to avoid double counting.
You also asked about both the anode and the cathode. The current for both will be the same number but with opposite sign.
