Week 1 Understanding Different Battery Chemistry

1.

TableIX enclosed herewith provides a comparative statement covering material of construction of anode and cathode as well as the chemical reaction taking place in anode and cathode for the six types of Lithium Ion batteries specified.The detailed explanation is as under.

A rechargeable Lithium ion battery consists of two electrodes called anode and cathode.While anode is typically made of graphite cathode is composed of layered Lithium transition metal oxide.Over and above the two electrodes in a Lithium ion battery we will have separator and electrolyte.The electrolyte is usually a solution of Lithium salts in a mixture of solvents like Dimethyl Carbonate or Diethyl Carbonate.

When the battery powers a device 'redox' process takes place wherein the graphite electrode is oxidised and the metal oxide electrode is reduced.Through this reverse process the Lithium ions from the graphite will migrate via the electrolyte back into the oxide electrode when there is electron movement in the external circuit powering the device.Thus at the anode Lithium is oxidised as Lithium ions are released from the carbon.On the other hand, at the cathode Lithium ions are absorbed by the Lithium Dioxide and the electrode is reduced since it receives electrons from the circuit.On charging of the battery the Lithium ions move from oxide electrode to the graphite electrode via the electrolyte and electron movement will take place via current collectors through an external circuit.On discharging the reverse process will occur.In this manner electrons will do the work and power the battery driven application.

2.

TableVIII enclosed herewith shows six types of Lithium ion batteries based on six yardsticks of Specific Power,Specific Energy,Safety,Lifespan,Cost and Performance.

It is being observed that LCO,NMC and NCA offer high level of Specific Energy.However, each of them is having moderate performance level.In so far as safety is concerned LFP and LTO are the most acceptable batteries.But the latter offers high cost also.The type of battery to be selected depends on the requirement of the user and the specific application.