How do Lithium Ion Rechargeable Batteries Work?

Lithium ion rechargeable batteries are indeed the most common energy sources. At present lithium based batteries are by far the most important storage systems available on the market. The working of lithium rechargeable batteries is discussed by taking LiCoO_2 and graphite as electrode materials.

Positive electrode: LiCoO_{2} <— > Discharge Charge Li1-xCoO_{2} + xLi^{+} + xe^{-}

Negative electrode: 6C + xLi^{+} + xe^{-} < — > Discharge Charge LixC_{6} + Li1 — xCoO_{2}

LiCoO_{2} has a stoichiometric octahedral lattice structure with an alternating arrangement of Li^{+} and Co^{3+} layers. During the charging process, lithium ions deintercalate from the layered structure of the positive electrode material, an electron is released and at the same time Co^{3+} is oxidized into Co^{4+}. With the discharging process with intercalation of Li^{+} into the lattice, Co^{4+} is reduced to Co^{3+}, gaining one electron.

In case of the negative electrode, graphite is used as an example. With the intercalation of Li^{+} into the interlayer of graphite one electron will be obtained from the lattice at the same time to turn into atomic state lithium. During the discharge process, atomic state lithium loses one electron to become a lithium ion and deintercalates from the graphene layers. Since lithium moves back and forth between the positive and the negative electrode, it used to be called a rocking chair battery.

Ideally the requirement for liquid lithium rechargeable batteries should have high lithium ion conductivity, good thermal stability and should not react over a wide temperature range. They should have a wide electrochemical voltage range and good chemical stability