Chemistry of a lithium-ion cell

Question

What exactly is the reaction that goes on within a lithium ion cell?

According to http://en.wikipedia.org/wiki/Lithium_ion_battery#Electrochemistry

LiCoO2 -> Li(1-x)CoO2 xe^- xLi^

If one electron and lithium ion is lost, would it be CoO2? I would think so but there is nothing called cobalt dioxide!

Is an ion left behind?

Also, according to http://en.wikipedia.org/wiki/Lithium_cobalt_oxide

the cobalt oxide parts are held together tightly while the lithium ions are in the middle...

How do we express this reaction in which lithium ions are lost from this compound?

Thanks,

Charith

Answer 1

In Li(1-x)CoO2, you have 1-x  Co in oxidation state +3 and x in oxidation state +4.

Yes, Co+4 does exist in solids.  It is also quite common for the same element to occur in two different oxidation states in an oxide framework; one example is magnetite, Fe3O4.

So when you charge the battery, you reduce Li+ to Li, which migrates out of the original LiCoO2, while oxidising Co to Co+4.

Answer 2

Li(1-x)CoO2 exist in a large range of x=0 to 0.8

LiCoO2 is rich in Li+ AND e- .the electron is some what

"free" it does not bond to Co4+

it is like in the case of the graphite(anode,other electrode)

a lithium battery works based on the fact that this couple (Li+ and e-) behave like

a GAS.A GAS THAT IS AT HIGH PRESSURE AT ONE ELECTRODE

AND LOW PRESSURE TO THE OTHER.ELECTRIC ENERGY STEMS

FROM THE 2 DIFFERENT ROUTES THOSE COMPONENTS PART:ELECTRONS THRU EXTERNAL CIRCUIT,Li+ THRU ELECTROLITE.if u take 2 graphite rods in an electrolite that contain Li

and u try to charge the cell,it will retain energy.PLANTE invented lead acid battery 150 years ago just trying the same:2 identical plates of lead in sulphuric acid(hoped to electrolise H2SO4).dissimilar electrodes are only to increase performance,it does not change the principle.

moreover:in graphite lithium is not in metallic state,it will not react with water.it.s just a pair (Li+ and e-) that is more or less appart