Week 1 Understanding Different Battery Chemistry

1. Table of materials and chemical reactions

Types	Chemical Name	Cathode Material	Chemical Reaction at Cathode	Anode Material	Chemical Reaction at Anode	Overall Reaction
Lithium Cobalt Oxide(LCO)	LiCoO2	Lithium Cobalt Oxide	CoO2 + Li+ + e- <-> LiCoO2	Graphite carbon	LiC6 <-> C6 + Li+ e-	LiCoO2 + C6 <-> LiC6 +CO2
Lithium Manganese Oxide (LMO)	LiMn2O2	Lithium Manganese Oxide	MnO2 + Li+ + e- <-> LiMnO2	Graphite carbon	LiC6 <-> C6 + Li+ e-	LiCo2 + C6 <-> LiC6 +Co02
Lithium Nickel Cobalt Aluminium oxide (NCA)	LiNiCoAlO2	Lithium Nickel cobalt aluminum oxide	NiCoAlO2 + Li+ + e- <-> LiNiCoAlO2	Graphite carbon	LiC6 <-> C6 + Li+ e-	LiCoO2 + C6 <-> LiC6 + CoO2
Lithium Nickel Manganese Cobalt Oxide(NMC)	LiNiMnCoO2	Lithium Nickel Manganese cobalt Oxide	NiMnCoO2 + Li+ + e- <-> LiNiMnCoO2	Graphite carbon	LiC6 <-> C6 + Li+ e-	LiCoO2 + C6 <-> LiC6 + CoO2
Lithium Iron Phosphate(LFP)	LiFePO4	Lithium Iron Phosphate	FePO4 + Li+ + e- <-> LiFePO4	Graphite carbon	LiC6 <-> C6 + Li+ e-	LiCoO2 + C6 <-> LiC6 + CoO2
Lithium Titanate Oxide(LTO)	LiTiO3	Manganese Oxide	4Mn2PO4 + PO4 + 4Li+ + e- <-> 4LiMn2O4	Graphite carbon	Li4Ti5O12 + 4Li+ +4e- <-> 4LiMn2O4	4Mn2O4 + Li4Ti5O12 <-> 4LiMn2O4 + Ti4O12

Lithium Cobalt Oxide (LiCoO2) - LCO

Its high specific energy makes Li-cobalt the popular choice for mobile phones, laptops and digital cameras. The battery consists of a cobalt oxide cathode and a graphite carbon anode. The cathode has a layered structure and during discharge, lithium ions move from the anode to the cathode. The flow reverses on charge. The drawback of Li-cobalt is a relatively short life span, low thermal stability and limited load capabilities (specific power).

The cathode has a layered structure. During discharge the lithium ions move from the anode to the cathode; on charge the flow is from cathode to anode.

The drawback of Li-cobalt is a relatively short life span, low thermal stability and limited load capabilities (specific power). Like other cobalt-blended Li-ion, Li-cobalt has a graphite anode that limits the cycle life by a changing solid electrolyte interface, thickening on the anode and lithium plating while fast charging and charging at low temperature.

Lithium Manganese Oxide (LiMn2O4) - LMO

The architecture forms a three-dimensional spinel structure that improves ion flow on the electrode, which results in lower internal resistance and improved current handling. A further advantage of spinel is high thermal stability and enhanced safety, but the cycle and calendar life are limited.

Low internal cell resistance enables fast charging and high-current discharging. In an 18650 package, Li-manganese can be discharged at currents of 20–30A with moderate heat buildup. It is also possible to apply one-second load pulses of up to 50A. A continuous high load at this current would cause heat buildup and the cell temperature cannot exceed 80°C (176°F). Li-manganese is used for power tools, medical instruments, as well as hybrid and electric vehicles.

The cathode crystalline formation of lithium manganese oxide has a three-dimensional framework structure that appears after initial formation. Spinel provides low resistance but has a more moderate specific energy than cobalt.

Li-manganese has a capacity that is roughly one-third lower than Li-cobalt. Design flexibility allows engineers to maximize the battery for either optimal longevity (life span), maximum load current (specific power) or high capacity (specific energy). For example, the long-life version in the 18650 cell has a moderate capacity of only 1,100mAh; the high-capacity version is 1,500mAh.

Lithium Nickel Cobalt Aluminum Oxide ( LiNiCoAlO2 ) - NCA

Lithium nickel cobalt aluminum oxide battery, or NCA, has been around since 1999 for special applications. It shares similarities with NMC by offering high specific energy, reasonably good specific power and a long life span. Less flattering are safety and cost.

Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2)- NMC

NMC in an 18650 cell for moderate load condition has a capacity of about 2,800mAh and can deliver 4A to 5A; NMC in the same cell optimized for specific power has a capacity of only about 2,000mAh but delivers a continuous discharge current of 20A. A silicon-based anode will go to 4,000mAh and higher but at reduced loading capability and shorter cycle life. Silicon added to graphite has the drawback that the anode grows and shrinks with charge and discharge, making the cell mechanically unstable.

The secret of NMC lies in combining nickel and manganese. An analogy of this is table salt in which the main ingredients, sodium and chloride, are toxic on their own but mixing them serves as seasoning salt and food preserver. Nickel is known for its high specific energy but poor stability; manganese has the benefit of forming a spinel structure to achieve low internal resistance but offers a low specific energy. Combining the metals enhances each other strengths.

NMC is the battery of choice for power tools, e-bikes and other electric powertrains.

Lithium Iron Phasphate (LiFePO4) - LFP

Li-phosphate is more tolerant to full charge conditions and is less stressed than other lithium-ion systems if kept at high voltage for a prolonged time. As a trade-off, its lower nominal voltage of 3.2V/cell reduces the specific energy below that of cobalt-blended lithium-ion. With most batteries, cold temperature reduces performance and elevated storage temperature shortens the service life, and Li-phosphate is no exception. Li-phosphate has a higher self-discharge than other Li-ion batteries, which can cause balancing issues with aging.Li-phosphate is often used to replace the lead acid starter battery. Four cells in series produce 12.80V, a similar voltage to six 2V lead acid cells in series. Vehicles charge lead acid to 14.40V (2.40V/cell) and maintain a topping charge.

Lithium Titanate (Li2TiO3) - LTO

Li-titanate replaces the graphite in the anode of a typical lithium-ion battery and the material forms into a spinel structure. The cathode can be lithium manganese oxide or NMC. Li-titanate has a nominal cell voltage of 2.40V, can be fast charged and delivers a high discharge current of 10C, or 10 times the rated capacity. The cycle count is said to be higher than that of a regular Li-ion. Li-titanate is safe, has excellent low-temperature discharge characteristics and obtains a capacity of 80 percent at –30°C (–22°F).

LTO (commonly Li4Ti₅O₁₂) has advantages over the conventional cobalt-blended Li-ion with graphite anode by attaining zero-strain property, no SEI film formation and no lithium plating when fast charging and charging at low temperature. Thermal stability under high temperature is also better than other Li-ion systems; however, the battery is expensive. At only 65Wh/kg, the specific energy is low, rivalling that of NiCd. Li-titanate charges to 2.80V/cell, and the end of discharge is 1.80V/cell.

2. Comparision between the batteries

Batteries	LCO	LMO	NCA	NMC	LFP	LTO
Voltages	3.6 V	3.7 V	3.6V	3.6V/3.7V	3.2V	2.4V
Specific Energy	150-200wh/kg	100-150 Wh/kg	200-260 Wh/kg	150 - 220 Wh/kg	90-120Wh/kg	50-80Wh/kg
Charge ( C- rate)	0.7 C - 1C	0.7C- 1C	0.7C	0.7C - 1C	1C	1C
Discharge ( C-rate)	1C	1C	1C	1C	1C	10C
Cycle life	500-1000	300-700	500	1000-2000	2000 and higher	3000-7000
Thermal Runaway(degree Celcius)	150	250	150	210	270	Safest
Applications	Mobile phone , laptops, cameras	Power Tools , Electric powertrains	Medical Devices, Electric Powertrain	E-bikes,Evs	Portable and stationary high load currents	UPS, Electric Powertrain, Solar Powered street lightings