For example, if I have the following data for a LiNi0,8Co0,15Al0,05O2 compound used in the cathode:
- Specific capacity = 200 mAh/g
- Average voltage = 3,7 V
I have no information about the anode.
Is it possible to know how much energy is stored in a battery which uses this compound as a cathode? Otherwise, what information is missing to know that?
Thank you very much.
Most, if not all, EV batteries have a carbon (graphite or hard carbon) negative electrode (should not use anode or cathode for rechargeable batteries) whose potential is close to that for lithium metal deposition. The specific charge capacity of a carbon negative electrode is about 360 mAh/g. Therefore, for each gram of the graphite negative electrode, 1.8 g of positive electrode are needed to equalise the charge capacity on the two electrodes. With the cell voltage of 3.7 V, the specific energy (not energy density) of the cell is
3.7*360/(1+1.8) = 476 mWh/g (or Wh/kg).
Of course, this is the theoretical value without considering other factors, such as the mass of current collectors, liquid electrolyte and membranes, and casing materials. Because these materials usually account for about 15% of the total mass of the battery, the specific energy of the battery is then 423 Wh/kg.
Article : Characterisation of a 200 kW/400 kWh Vanadium Redox Flow Battery
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