Week 1 Understanding Different Battery Chemistry
1.Prepare a table which includes materials & chemical reactions occurring at the anode and cathode of LCO, LMO, NCA, NMC, LFP and LTO type of lithium ion cells.Give your detailed explanation on it
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* A Li-ion battery is said to be collection os several Li-ion cells in series and paralle connections
* The battery is madeup of an anode (-ve terminal) a cathode (+ve terminal) seperator, electrolyte, current collectors, The anode and cathode stores the Li-ions
* The electrolyte carries +vely charged Li-ions from anode to cathode through the seperators The movement of lithium ions makes free
*Electrons in anode which creates the charge at +ve current collectors makes them discharging and vise versa during charging. The electrons move through external circuits They cannot move through the electrolyte and sepeartors electrolyte and seperators only allows the ions transfer from anode to cathode to cathode & viseversa
* While the battery is discharging and providing the electric current the anode releases lithium ions to the cathode generating flow of electrons from anode to cathode which means current direction is from cathode to anode
* When plugging in the device Li-ions are released by cathode and received by anode That is the electrons flow into the anode makes current direction from anode to cathode
* The above charging and discharging operations are held at every cells of the battery combaining the o/p voltage and current to connected load/charging ports.
Here below shown the various components of Li-ion battery as we seen above.
The Li-ion battery chemical compositions varies according to different materials used in it thier cathode and anode parts
Various chemical compositions used in cathode are
* LCO- Lithium Cobalt oxide (LiCoO2)
* LPFP- Lithium Iron Phosphate (LiFePO4)
* LMO- Lithium Manganese Oxide ( LiMn2O4)
* NMC- Lithium Nickel Manganese Cobalt oxide (LiNiMnCoO2)
* NCA- Lithium Nickel Cobalt Aluminium Oxide (LiNiCoAlO2)
* LTO- Lithium Titanium Oxide (LiTiO3)
The anode materials are usually
* Graphite
* Hard Carbon
* Lithium Titanate
* Tin/ Cobalt alloy.
* Silicon/ Carbon
Chemical Reactions take place in anode and cathode
In these equations the charging denotes from right to Left and discharging denotes Left to right.
1.LCO-- At anode LiC6-C6+Li+e-
At Cathode CoO2+Li+e-= LicoO2
Overall Relation LicoO2+C6-LiC6+CoO2
2. LMO At anode LiC6-C6+Li+e-
At Cathode Mno2+Li+e- = LiMnO2
Overall Reaction LiMno2+C6= LiC6+MnO2
3. NCA At anode LiC6-C6+Li+e-
At cathode NiCoAlo2+Li+e- = LiNiCoAIO2
Overall Reaction C6Li+NiCoAIO2 - LiCoAlO2+C6
4. NMC At Anode LiC6-C6+Li+e-
At Cathode NiMnCoO2+Li+e- - LiNiMnCoO2
Overall Reaction LiC6+NiMnCoO2-LiNiMnCoO2+ C6
5. LFP At Anode LiC6-C6+Li+e-
At Cathode FePo4+Li+e- = LiFePo4
Overall Reaction LiC6+FePo4- LiFePO4+C6
6. LTO At Anode Li2TiO3-TiO2+Li+e-
At Cathode Mn2O4+Li+e- = LiMn2O4
Overall Reaction Li2TiO3+2Mn2O4 - 2LiMn2O4+TiO3
2.Compare the differences between each type of Li+ion batteries based on their characteristics
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Lithium Cobalt Oxide:
* This battery has the highest energy density. The specific energy is in the range of 150 to 200 Wh/Kg.
* The limitation is thermal instablitiy the anode can overheat. At high temp the cathode can decompose and produce oxygen SOmetimes the electrolute used is diethyl carbonate which is flammable in nature hence, this type of battery can catch fire due to overheating the thermal runaway occurs at 150 degree c
* It has a short life span due to formation of solid Electrolyte Layer (SEI) at anode and lithium plating due to fast charging and charging at low temp.
TYpically it has life span of 500 to 1000 cycles
* It has limited load capabilities since it cannot be charged or discharged beyond its C-rate should be maintained in the range of 0.7 c to 1c.
Applications: Mobile phones, Laptops, camera etc.
Lithium Manganese Oxide:
* The spinel structure (AB2O4 Structure) of Lithium manganese enables this type of battery to have better thermal stability so it is better in terms of safety The high charge promotes thermal runaway at a high temp of 250c
* The Spinel structure promotes the ion flow within the electrolyte and this reduces the internal resistance of the battery
* The limitation is that it loses the battery power over time
* It has shorter lifetime of 300-700 cycles and lower capacity The specific energy of this battery is 100-150 Wh/kg
* it has ability to charge and discharge at higher C-rate, So it is used for a high current boost on acceleration in EV.
Application: Power tools, Medical devices, Electrical Power trains.
Lithium Nickel Manganese Cobalt Oxide:
* This type of battery has the advantage of Lithium cobalt oxide. & Lithium Manganse Oxide
* Thermal runaway occurs at a high temp of 210c
* It has a life span of 1000 to 2000 cycles
* This combination has a mixture of one third nickel, one third Cobalt, and one third Manganese, Cobalt is expensive and limited in supply. Hence the proportion of cobalt in the recent batteries
* This battery is preferred for electric vehicles due to its low self heating rate
Lithium Iron Phosphate:
* This battery has a high discharge rate because of low internal resistance made possible by nano scale phosphate cathode material
* Due to the presence of phosphate (PO4) that can cope up with high temp At cathode Phosphate anions are bonded with iron cations. This structure holds the oxygen molecules tightly and give cathode chemical stability This battery has good thermal stability Thermal runaway is caused at 270 c
* It can be used for higher number of discharge cycles as high as 2000
* It has higher self discharge rate
* This battery is more tolerant to full charge and less stressed when kept at full voltage for prolonged period.
Application: It is used in stationary and portable devices needing high load current and endurance
Lithium Nickel Cobalt Aluminium Oxide:
* It is a further development of lithium Nickel oxide Adding Auminium to the chemistry gives the battery greater stability
* It has feature similar to NMC Battery high specific energy (200-260 Wh/kg) Good specific power and a long life span
Applications: Medical Equipments and EV (Tesla)
Lithium Titanate:
In this battery Graphite as anode is replaced by Lithium Titanate formed into a spinel strcture
* It has fast charge capability and a high discharge curent of 10c which is 10 times the usual capacity
* This battery is safe it has good low temp. discharge capability and can acheive c charger level of 80% atv -30 c
* It is advantage over lithium cobalt oxide because ther is no solid Electrolyte interface formation or lithium plating while fast charging or discharging at low temp
* It has a greater life span than any other Lithium-ion battery It can go up to 5000 Cycles.
Applications: Electrical Powertrains, SOlar Street lights.