Week 1 Understanding Different Battery Chemistry

AIM: To understand different Battery Chemistry (Lithium-ion battery)

OBJECTIVES:

• Try to prepare the table for different materials and chemical reaction of cathode and anode for different types of lithium-ion batteries.
• Compare different between each characteristic for different types of lithium-ion batteries.

 

 

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.

A lithium-ion (Li-ion) battery is an advanced battery technology that uses lithium ions as a key component of its electrochemistry. During a discharge cycle, lithium atoms in the anode are ionized and separated from their electrons. The lithium ions move from the anode and pass through the electrolyte until they reach the cathode, where they recombine with their electrons and electrically neutralize. The lithium ions are small enough to be able to move through a micro-permeable separator between the anode and cathode. In part because of lithium’s small size (third only to hydrogen and helium), Li-ion batteries are capable of having a very high voltage and charge storage per unit mass and unit volume.

                                                                

Li-ion batteries can use a number of different materials as electrodes. The most common combination is that of lithium cobalt oxide (cathode) and graphite (anode), which is most commonly found in portable electronic devices such as cell phones and laptops. Other cathode materials include lithium manganese oxide (used in hybrid electric and electric automobiles) and lithium iron phosphate. Li-ion batteries typically use ether (a class of organic compounds) as an electrolyte.

                                        

 

Types of Lithium-ion Battery’s

1. Lithium Cobalt Oxide (LiCoO₂) – LCO
2. Lithium Manganese Oxide (LiMn₂O₄) – LMO
3. Lithium Nickel Cobalt Aluminium Oxide (LiNiCoAlO₂) – NCA
4. Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO₂) – NMC
5. Lithium Iron Phosphate (LiFePo₄) – LFP
6. Lithium Titanate (Li₂TiO₃) – LTO

 

• Lithium Cobalt Oxide (LiCoO₂) – LCO

Cathode material: Lithium Cobalt Oxide

Anode material: Graphite

Cathode Reaction: CoO₂ + Li⁺ +e^- = LiCoO2

Anode Reaction: LiC₆ = C₆ + Li⁺ +e^-

Overall Reaction: C₆ + LiCoO₂ = LiC₆ +CoO₂

 

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).

                                                             

Li-cobalt should not be charged and discharged at a current higher than its C-rating. This means that an 18650 cell with 2,400mAh can only be charged and discharged at 2,400mA. Forcing a fast charge or applying a load higher than 2,400mA causes overheating and undue stress. For optimal fast charge, the manufacturer recommends a C-rate of 0.8C or about 2,000mA. The mandatory battery protection circuit limits the charge and discharge rate to a safe level of about 1C for the Energy Cell.

                                                                          

Li-cobalt excels on high specific energy but offers only moderate performance specific power, safety and life span.

The hexagonal spider graphic summarizes the performance of Li-cobalt in terms of specific energy or capacity that relates to runtime; specific power or the ability to deliver high current; safety; performance at hot and cold temperatures; life span reflecting cycle life and longevity; and cost. Other characteristics of interest not shown in the spider webs are toxicity, fast-charge capabilities, self-discharge and shelf life.

The Li-cobalt is losing favour to Li-manganese, but especially NMC and NCA because of the high cost of cobalt and improved performance by blending with other active cathode materials. (See description of the NMC and NCA.

 

• Lithium Manganese Oxide (LiMn₂O₄) – LMO

Cathode material: Lithium Manganese Oxide

Anode material: Graphite

Cathode Reaction: MnO₂ + Li⁺ +e^- = LiMnO2

Anode Reaction: LiC₆ = C₆ + Li⁺ +e^-

Overall Reaction: C₆ + LiMnO₄ = LiC₆ +Mn₂O₄

 

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 build-up. It is also possible to apply one-second load pulses of up to 50A. A continuous high load at this current would cause heat build-up 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.

formation of a three-dimensional crystalline framework on the cathode of a Li-manganese battery. This spinel structure, which is usually composed of diamond shapes connected into a lattice, appears after initial formation.

                                                                   

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.

                                                                         

Although moderate in overall performance, newer designs of Li-manganese offer improvements in specific power, safety and life span.

The characteristics appear marginal but newer designs have improved in terms of specific power, safety and life span. Pure Li-manganese batteries are no longer common today; they may only be used for special applications.

• Lithium Nickel Cobalt Aluminium Oxide (LiNiCoAlO₂) – NCA

Cathode material: Lithium nickel cobalt aluminium oxide

Anode material: Graphite

Cathode Reaction: NiCoAlO₂ + Li⁺ +e^- = LiNiCoAlO₂

Anode Reaction: LiC₆ = C₆ + Li⁺ +e^-

Overall Reaction: C₆ + LiNiCoAlO₂ = LiC₆ + NiCoAlO₂

 

Lithium nickel cobalt aluminium 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. NCA is a further development of lithium nickel oxide; adding aluminium gives the chemistry greater stability.

                                                                              

High energy and power densities, as well as good life span, make NCA a candidate for EV powertrains. High cost and marginal safety are negatives.

• Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO₂) – NMC

Cathode material: Lithium Nickel Manganese Cobalt Oxide

Anode material: Graphite

Cathode Reaction: NiMnCoO₂ + Li⁺ +e^- = LiNiMnCoO₂

Anode Reaction: LiC₆ = C₆ + Li⁺ +e^-

Overall Reaction: C₆ + LiNiMnCoO₂ = LiC₆ + NiMnCoO₂

 

One of the most successful Li-ion systems is a cathode combination of nickel-manganese-cobalt (NMC). Similar to Li-manganese, these systems can be tailored to serve as Energy cells or Powe cells.

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 has good overall performance and excels on specific energy.
This battery is the preferred candidate for the electric vehicle and has the lowest self-heating rate

There is a move towards NMC-blended Li-ion as the system can be built economically and it achieves a good performance. The three active materials of nickel, manganese and cobalt can easily be blended to suit a wide range of applications for automotive and energy storage systems (EES) that need frequent cycling. The NMC family is growing in its diversity.

• Lithium Iron Phosphate (LiFePo₄) – LFP

Cathode material: Lithium Iron Phosphate

Anode material: Graphite

Cathode Reaction: FePo₄ + Li⁺ +e^- = LiFePo₄

Anode Reaction: LiC₆ = C₆ + Li⁺ +e^-

Overall Reaction: C₆ + LiFePo₄ = LiC₆ + FePo₄

 

Li-phosphate offers good electrochemical performance with low resistance. This is made possible with nano-scale phosphate cathode material. The key benefits are high current rating and long cycle life, besides good thermal stability, enhanced safety and tolerance if abused.

With four Li-phosphate cells in series, each cell tops at 3.60V, which is the correct full-charge voltage. At this point, the charge should be disconnected but the topping charge continues while driving. Li-phosphate is tolerant to some overcharge; however, keeping the voltage at 14.40V for a prolonged time, as most vehicles do on a long road trip, could stress Li-phosphate. Time will tell how durable Li-Phosphate will be as a lead acid replacement with a regular vehicle charging system. Cold temperature also reduces performance of Li-ion and this could affect the cranking ability in extreme cases.

                                                                             

Li-phosphate has excellent safety and long-life span but moderate specific energy and elevated self-discharge.

 

Lithium Titanate (Li₂TiO₃) – LTO

Cathode material: Lithium manganese oxide

Anode material: Li-titanate

Cathode Reaction: 4Mn₂O₄ + 4Li⁺ + 4e^- = 4LiMn₂O₄

Anode Reaction: Li₄Ti₅O₁₂ = Ti₅O₁₂ + 4Li⁺ + 4e^-

Overall Reaction: 4Mn₂O₄ + Li₄Ti₅O₁₂ = 4LiMn₂O₄ + Ti₅O₁₂

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. Typical uses are electric powertrains, UPS and solar-powered street lighting.

                                                                         

Li-titanate excels in safety, low-temperature performance and life span. Efforts are being made to improve the specific energy and lower cost.

 

Comparing Types of Lithium-ion batteries with there cathode and anode materials and chemical reactions

Types of Li-ion batteries	Cathode Material	Anode Material	Cathode Reaction	Anode Reaction	Overall Reaction
LCO	Lithium cobalt oxide	Graphite	CoO2 + Li+ +e- = LiCoO2	LiC6 = C6 + Li+ + e-	C6 + LiCoO2 = LiC6 +CoO2
LMO	Lithium manganese oxide	Graphite	MnO2 + Li+ +e- = LiMnO2	LiC6 = C6 + Li+ + e-	C6 + LiMnO4 = LiC6 +Mn2O4
NCA	Lithium nickel cobalt aluminium oxide	Graphite	NiCoAlO2 + Li+ +e- = LiNiCoAlO2	LiC6 = C6 + Li+ + e-	C6 + LiNiCoAlO2 = LiC6 + NiCoAlO2
NMC	Lithium Nickel Manganese Cobalt Oxide	Graphite	NiMnCoO2 + Li+ +e- = LiNiMnCoO2	LiC6 = C6 + Li+ + e-	C6 + LiNiMnCoO2 = LiC6 + NiMnCoO2
LFP	Lithium Iron Phosphate	Graphite	FePo4 + Li+ +e- = LiFePo4	LiC6 = C6 + Li+ + e-	C6 + LiFePo4 = LiC6 + FePo4
LTO	Lithium manganese oxide	Li-titanate	4Mn2O4 + 4Li+ + 4e- = 4LiMn2O4	Li4Ti5O12 = Ti5O12 + 4Li+ + 4e-	4Mn2O4 + Li4Ti5O12 = 4LiMn2O4 + Ti5O12

2. Compare the differences between each type of Li-ion batteries based on their characteristics.

Comparing types of Lithium-ion Batteries with their Characteristics:

	LCO	LMO	NCA	NMC	LFP	LTO
Voltages	3.60V nominal; typical operating range 3.0–4.2V/cell	3.70V (3.80V) nominal; typical operating range 3.0–4.2V/cell	3.60V nominal; typical operating range 3.0–4.2V/cell	3.60V, 3.70V nominal; typical operating range 3.0–4.2V/cell, or higher	3.20, 3.30V nominal; typical operating range 2.5–3.65V/cell	2.40V nominal; typical operating range 1.8–2.85V/cell
Specific energy (capacity)	150–200Wh/kg. Specialty cells provide up to 240Wh/kg.	100 - 150Wh/kg	200-260Wh/kg; 300Wh/kg predictable	150–220Wh/kg	90–120Wh/kg	50–80Wh/kg
Charge (C-rate	0.7–1C, charges to 4.20V (most cells); 3h charge typical. Charge current above 1C shortens battery life.	0.7–1C typical, 3C maximum, charges to 4.20V (most cells)	0.7C, charges to 4.20V (most cells), 3h charge typical, fast charge possible with some cells	0.7–1C, charges to 4.20V, some go to 4.30V; 3h charge typical. Charge current above 1C shortens battery life.	1C typical, charges to 3.65V; 3h charge time typical	1C typical; 5C maximum, charges to 2.85V
Discharge (C-rate)	1C; 2.50V cut off. Discharge current above 1C shortens battery life.	1C; 10C possible with some cells, 30C pulse (5s), 2.50V cut-off	1C typical; 3.00V cut-off; high discharge rate shortens battery life	1C; 2C possible on some cells; 2.50V cut-off	1C, 25C on some cells; 40A pulse (2s); 2.50V cut-off (lower that 2V causes damage)	10C possible, 30C 5s pulse; 1.80V cut-off on LCO/LTO
Cycle life	500–1000, related to depth of discharge, load, temperature	300–700 (related to depth of discharge, temperature)	500 (related to depth of discharge, temperature)	1000–2000 (related to depth of discharge, temperature)	2000 and higher (related to depth of discharge, temperature)	3,000–7,000
Thermal runaway	150°C (302°F). Full charge promotes thermal runaway	250°C (482°F) typical. High charge promotes thermal runaway	150°C (302°F) typical, High charge promotes thermal runaway	210°C (410°F) typical. High charge promotes thermal runaway	270°C (518°F) Very safe battery even if fully charged	One of safest Li-ion batteries
Cost	$210 per kWh	$280 per kWh	$350 per kWh	$420 per kWh	$580 per kWh	$1,005 per kWh
Applications	Mobile phones, tablets, laptops, cameras	Power tools, medical devices, electric powertrains	Medical devices, industrial, electric powertrain (Tesla)	E-bikes, medical devices, EVs, industrial	Portable and stationary needing high load currents and endurance	UPS, electric powertrain (Mitsubishi i-MiEV, Honda Fit EV), solar-powered street lighting

CONCLUSION:

Hence, we have prepared the table for different materials and chemical reaction of cathode and anode for different types of lithium-ion batteries and compared different between each characteristic for different types of lithium-ion batteries.

 

REFERENCES:

https://batteryuniversity.com/article/bu-205-types-of-lithium-ion