Week 1 Understanding Different Battery Chemistry

Types of lithium-ion cells	Chemical reaction			Type of Material Used
	Anode	Cathode	Overall reaction	Anode	Cathode	Electrolyte	Separator
LCO (Lithium Cobalt oxide) – LiCoO2	LiC6 = C6 + Li+ + e-	CoO2 + Li+ + e- = LiCoO6	C6 + LiCoO6 = LiC6 + CoO2	Graphite carbon	Cobalt oxide	Ethylene carbonate	polyolefin
LMO (Lithium Manganese) – LiMn2O4	LiC6 = C6 + Li+ + e-	MnO2 + Li+ + e- = LiMn2O4	C6 + LiMn2O4 = LiC6 + MnO2	Graphite carbon	Lithium manganese oxide	Lithium halide	polyolefin
NCA (Lithium Nickel Cobalt Aluminium Oxide) – LiNiCoAlO2	LiC6 = C6 + Li+ + e-	NiCoAlO2 + Li+ + e-= LiNiCoAlO2	C6 + LiNiCoAlO2 = LiC6 + NiCoAlO2	Graphite carbon	Nickel Cobalt Aluminium	Ethylene carbonate	polyolefin
NMC ( Lithium Nickel Manganese Cobalt oxide) - Li(NiCoMn)O2	LiC6 = C6 + Li+ + e-	NiCoMn + Li+ + e-= Li(NiCoMn)O2	C6 + Li (NiCoMn)O2 = LiC6 + NiCoMn	Graphite carbon	Nickel Manganese Cobalt	Lithium salt	polyolefin
LFP (Lithium Iron Phosphate) - LiFePO4	LiC6 = C6 + Li+ + e-	FePO4 + Li+ + e-= LiFePO4	C6 + LiFePO4 = LiC6 + FePO4	Graphite carbon	Lithium iron phosphate	Ethylene carbonate	polyolefin
LTO (Lithium Titanate) – Li2 Ti O3	Li4Ti5O12 = Ti5O12 + 4 Li+ + 4 e-	8 MnO2 +4 Li+ +4 e- = 4LiMn2O4	Li4Ti5O12 + 8 MnO2 = Ti5O12 + 4LiMn2O4	Manganese oxide	Lithium Titanate	Lithium salt	polyolefin

Answer 1:

Lithium-Ion (Li-ion) batteries are type of rechargeable batteries with high energy and power capabilities. It is an advanced battery technology with lithium ions as a key component of its electrochemistry. Li-ion batteries use an intercalated lithium compound like Lithium Cobalt Oxide (LiCoO2), Lithium Manganese Oxide (LiMn2O4) and Lithium Nickel Oxide (LiNiO2) as the material at the positive electrode and typically graphite intercalation material at the negative electrode. This anode and cathode assembly is isolated electrically with separator and is impregnated in electrolyte of organic solvent consisting lithium salt. Lithium-Ion batteries find applications from normal electronics gadgets applications to high-power applications like Electric Vehicles because of high flexibility in the construction of lithium-ion cells with respect to very high electrode surface area and their chemistry.

Lithium-Ion Battery technology is based on Intercalation, which is actually the addition of lithium ions into a host material without significantly changing the host's structure. During the discharge cycle, lithium atoms in the anode are ionized and stripped of electrons. Lithium ions migrate from the anode through the electrolyte medium, through a micro permeable separator between the anode and cathode, and reach the cathode where they recombine with electrons. Lithium ions are small enough (third size after hydrogen and helium) to allow fast charging/discharging capability per unit mass and unit volume and high charge storage capacity. The single cell voltage of a lithium-ion battery is the voltage difference between the Li+ ions present in the crystal structures of the two electrodes.

Apart from the three critical components namely cathode, anode and electrolyte, other important and integral part of a lithium-ion battery are the electronic controller (that monitors performance), discharge flow and battery temperature. Due to the high reactivity of lithium-ion batteries, the integration of this electronic device requires special safety measures to ensure that the operating conditions of the lithium battery are kept within safe limits. Different types of lithium-ion batteries and their properties are discussed below.

LCO lithium-ion battery _- Lithium cobalt oxide (LiCoO2) is a mature battery technology characterized by long life and high energy density. The cathode consists of cobalt oxide and the anode consists of graphite carbon. The cathode has a layered structure, and lithium ions move from the anode to the cathode during discharge. When charging, the flow is reversed. The drawbacks of Li-Cobalt are its relatively short lifetime, poor thermal stability and limited power handling (specific power).

Specifications of LCO with Graphite anode:

Voltages: 3.60V nominal; typical operating range 3.0–4.2V/cell

Specific Energy: 150–200Wh/kg. Specialty cells provide up to 240Wh/kg.

Charge (C-rate): 0.7–1C, charges to 4.20V

Discharge (C-rate): 1C; 2.50V cut off. Discharge above 1C shortens battery life.

Cycle life: 500–1000, related to depth of discharge, load, temperature

Thermal runaway: 150°C. Full charge promotes thermal runaway

Applications: Mobile phones, tablets, laptops, cameras

Lithium manganese (LMO): The cathode of lithium manganese battery cells is composed of lithium manganese oxide (LiMn2O4). It forms a three-dimensional spinel structure that improves ion flow on the electrodes, resulting in lower internal resistance and improved current handling compared to cobalt-based batteries. The three-dimensional spinel architecture also exhibits high thermal stability and improved safety, but at the expense of cycles, life, and energy density. Pure lithium manganese batteries are no longer common and may only be used for special applications. Recent trends show that most lithium manganese batteries are mixed with lithium nickel manganese cobalt oxide (NMC) to improve specific energy and extend life, which is popular in most electric vehicles.

Specifications of LMO with Graphite anode:

Voltages: 3.70V (3.80V) nominal; typical operating range 3.0–4.2V/cell

Specific Energy: 100–150Wh/kg

Charge (C-rate): 0.7–1C typical, 3C maximum, charges to 4.20V (most cells)

Discharge (C-rate): 1C; 10C possible with some cells, 30C pulse (5s), 2.50V cut-off

Cycle life: 300–700 (related to depth of discharge, temperature)

Thermal runaway: 250°C typical. High charge promotes thermal runaway

Applications: Power tools, medical devices, electric powertrains

Lithium Nickel Cobalt Alumina (NCA): Lithium Nickel Cobalt Alumina (LiNiCoAlO2) cathode material is a very thermally stable cathode material. Aluminium doping of Lithium Nickel Cobalt Oxide stabilizes both thermal and charge transfer resistance. NCAs are similar to NMCs in that they offer high specific energy, fairly good specific power, and long life. High energy and power density and excellent durability make NCA a good candidate for EV powertrain.

Specifications:

Typical operating range: 3.0-4.2 V/cell

specific energy: 200-260 Wh/kg; predictable 300 Wh/kg

charge (C rate): 0.7 C, charge to 4.20 V, typical 3-hour charge, rapid Rechargeable

discharge (C rate): 1 C typical; 3.00V shutdown; high discharge rate reduces battery life.

Cycle Life: 500 (based on depth of discharge, temperature)

Thermal Runaway: 250°C (typical). High charge promotes thermal runaway

Applications: medical equipment, industrial, electric powertrain

Lithium Nickel Manganese Cobalt Oxide (NMC): Lithium Nickel Cobalt Manganese (Li (NiCoMn)O2) batteries consist of a cathode material that is a combination of nickel, manganese, and cobalt, typically about one-third nickel and manganese is one-third and cobalt is one-third. Also known as 1-1-1. Like lithium manganese, NMCs can be tuned to function as energy or power cells. Like other lithium-ion battery variants, NMC batteries can have either high specific energy density or high specific power. However, both properties cannot be in the same pack. For example, in a moderately loaded 18650 cells, the NMC has a capacity of about 2,800mAh and can deliver 4A-5A. An NMC with the same cell size can be optimized for a specific power with a capacity of around 2000mAh, yet capable of delivering 20A of continuous discharge current.

Specifications:

Voltage: 3.60V, 3.70V nominal.

Typical operating range >3.0-4.2V/cell

specific energy: 150-220Wh/kg

charge (C rate): 0.7-1C, charge to 4.20V, some to 4.30V. Normal charging time is 3 hours.

discharge (C rate): 1C; 2C possible in some cells. 2.50V shutdown

cycle life: 1000 to 2000 (related to depth of discharge, temperature)

thermal runaway: 210°C

Lithium-Ion Phosphate (LFP): Lithium iron phosphate (LiFePO4) batteries use lithium phosphate as the cathode material. Lithium phosphate offers excellent electrochemical performance with low resistance. This nanoscale phosphate material for lithium-ion battery cathodes is the most performed due to its low cost, environmental friendliness, long cycle and life (chemical stability), and excellent capacity (170 mAh/g). Doping with transition metals leads to lower internal impedance. LiFePO4 batteries are non-flammable when charged and discharged, are stable under overcharge and short circuit conditions, and can withstand high temperatures without decomposition. LFPs are more tolerant of fully charged conditions and are relatively less stressed when held at high voltages for extended periods of time.

Specifications for LFP with Graphite Anode:

Voltage: 3.20, 3.30 V nominal. Typical operating range 2.5 to 3.65 V/cell

specific energy: 90 to 120 Wh/kg

charging (C rate): typically, 1 C, charging to 3.65 V; Typical 3-hour charge time

discharge (C rate): 1C, 25C for some cells. 40A pulse (2 sec); 2.50V shutdown

cycle life: >2000 (depth of discharge, temperature dependent)

thermal runaway: 270°C Very safe battery even when fully charged

application: high load current and for durability and electric powertrains

Discharging below 2V LFP can damage it.

Lithium titanate (LTO): Lithium titanate ((Li2TiO3)) batteries are improved lithium-ion batteries in which the graphite in the anode is replaced with lithium titanate, which forms a spinal structure. The cathode can be lithium manganate, NMC, LFP, or any other lithium battery cathode. LTO has a nominal cell voltage of 2.40V, is capable of fast charging, and can deliver a high discharge current of 10C. The cycle life is also longer than regular lithium-ion batteries. LTO has excellent low temperature discharge characteristics (80% capacity at -30 °C). It has relatively good thermal stability at high temperatures and is very resistant to operational use, easily operating up to 55°C and can reach up to 65°C.

Standard specification with LTO (Li2TiO3) as anode and LMO or NMC as cathode

Voltage: 2.40 V nominal. Typical operating range 1.8 to 2.85 V/cell

specific energy: 50 to 80 Wh/kg

charge (C rate): 1 C standard. Charge up to 5C, 2.85V

Discharge (C rate): 10C possible, 30C 5 sec pulse.

Cycle Life: 3000 to 7000

Thermal Runaway: One of the Safest Lithium-Ion Batteries

Applications: UPS, Electric Powertrains, Solar Powered Street Lights

Answer 2:

A Lithium-ion battery technology has proved to be very important innovation for the world. It is a rechargeable battery technology that is being used in multitude of electrical, mechanical and electronic devices like phones, cars, calculators, watches, satellites, etc. Different lithium-ion batteries have different advantages and disadvantages. In the following table we will compare them with 1 to 4 for different characteristic based on uses where 0 is lowest and 4 is highest.

Types of batteries	Specific energy	Specific power	Safety	Performance	Life span	Cost
LCO	4	2	2	3	2	3
LMO	3	3	3	2	2	3
NCA	4	3	2	3	3	2
NMC	4	3	3	3	3	3
LFP	2	4	4	3	4	2
LTO	2	3	4	4	4	1

Specific energy: This is battery capacity (Wh) compared to weight (kg).

Specific power: It is the ability to deliver high current.

Safety: This defines the operating condition stability such as thermal, materials and others.

Performance: This investigates the of overall performance of the battery over wide range of temperatures.

Life span: This details the total charging and discharging cycles for the battery over time.

Cost: Cost of production and buying cost of finished product also determines the choice of the battery type.