Li-Ion Batteries Flashcards
What is a battery?
A device containing multiple electrochemical cells that can store electrical energy through electrochemical reactions.
Name all the parts of the an electrochemical cell
Negative Anode, Positive Cathode, Separator, External Circuit, Electrolyte
Draw the structure of an electrochemical cell
*See notes
How does an electrochemical cell operate?
Negative anode and positive cathode are immersed in electrolyte and are connected by an external circuit
They are kept apart by a separator
When connected the ions flow through the electrolyte, and across the separator
Electrons flow around the external circuit
Electrical work is produced which = current
What is an ion?
A charged particle
What is a separator and what is its function?
A separator is a porous, electrically insulating barrier between electrodes that allows for ionic movement
What is the electrolyte?
The electrolyte is a non-aqueous, ionically conductive (Li+), electrically insulating solution
Why do batteries use lithium?
Lowest density metal (0.534 g/cm3)
Highest energy-to-weight ratio
Low atomic weight and small ionic radius helps with diffusion
Name the materials commonly found in a lithium-ion battery
–ve current collector (e.g. Cu)
+ve current collector (e.g. Al)
Non-aqueous Li-salt electrolyte
Insulating separator porous to ions
Negative electrode: Graphite “Anode”
Positive electrode: Crystalline transition
metal oxide/phosphate solid that Li can
intercalate (multiple options) “cathode”
Different current collectors
The negative electrode “Anode” is commonly made from what?
Graphite
The positive electrode is commonly made from what? (Name all four)
LCO
LFP
NMC
LMO
The positive electrode material must have what characteristics? (Name any three)
Good ionic and electronic conductor
Large specific Li-ion capacity
High potential difference
Stable
Non-toxic
Transition metal to provide the redox
couple
Small volume change
Most common positive electrode
materials have poor conductivity and
so are mixed with conductive carbon
and binder
What is thermal runaway?
Elevated temperature, caused by environmental conditions or too rapid discharge (including shorting) causing the breakdown of electrolyte, or separator which causes further chemical reactions that also release more heat leading to explosions, fires.
Why choose graphite for the negative electrode?
Low cost
Abundant
Good electrical conductivity
How many carbon atoms for 1 Li atom?
6
