Actually, people usually using carbon combine with active material like Fe3O4, FeF2, Fe2O3, etc. many researcher work using some active compound and add carbon to their active material and can we change that carbon to become silicon? because I thought silicon have some similar characteristics with carbon.
Dear Maulana,
Researchers really add carbon to their active material using carbon as a conductive additive (~1000 Sm/cm). We can't use silicon instead of carbon because silicon has low electric conductivity (~0.00001 Sm/cm).
Dear Maulana,
You use materials to perform specific function or functions in the device. Carbon is used here as a negative electrode which must be good conducting and it must maximize work function difference between the anode and cathode of the cell. It must remain chemically unchanged. Silicon easily can oxidized by the ambient oxide. Even if it is heavily doped its conductivity remains much smaller than that of graphite. The issue of the work function needs to be compared. Mechanically it is easy to shape.
Graphite has long history as a cathodes for chemical batteries!
Best wishes
thanks a lot for your answer... now, I know why people not trying using Si for replacing carbon.
Dear Maulana,
carbon performs two principal functions in a lithium ion battery:
a) Anode active material: Graphitic carbon intercalates lithium ions between the graphene layers, leading to lithium storage with a capacity up to theoretically 372 mAh/g (theor.). In this function, carbon can be exchanged by silicon because silicon also can intercalate lithium ions, leading to lithium storage with a capacity up to 4200 mAh/g (theor.). The use of silicon instead of carbon as anode active material is of great interest for increasing the energy densitiy of lithium ion cells.
b) Conducitve additive: carbon is used as conductive additive in an electrode layer in form of carbon blacks or - in special cases - carbon nanotubes or graphene. The carbon black ensures the electric contakt between the active material particles among themselves and with the collector. In this function, it cannot be recommended to substitute carbon by silicon due to the low electric conductitivy of silicon.
Best regards!
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials
- Carbon Materials