Week 1 Understanding Different Battery Chemistry

Cobalt acid lithium battery has high discharge platform, high specific capacity, stable product performance, and good cycle performance, but its safety performance is poor. The cost is very high, it is mainly used for medium and small type batteries, which is widely used in mobile phones, portable computers, cameras, camera, electric cars, solar energy storage, UPS power supply, medical equipment, space and other fields. The nominal voltage is 3.7V.

Lithium cobalt oxide, LiCoO2 (LCO), is an inorganic compound commonly used as a anode material for lithium ion batteries.

Lithium cobalt oxide battery mainly relies on the intercalation and disintercalation of lithium ions between anode and cathode to realize the storage and release of energy.

While charging, at the external electric field, lithium elements in the LiCoO2 molecules of the anode material become lithium ion with positive charge, which moves from the anode to cathode. After chemical reaction with the carbon atoms of the cathode, LiC6 is formed, which is stably embedded into the layered graphite cathode.

When discharging, on the contrary, in the internal electric field turns, Li+ breaks away from the cathode, goes along the direction of the electric field, returns to the anode, and then becomes LiCoO2. This process called a "rocking chair battery". The more lithium ions involved in back-and-forth embedding and disembedding activities, the more energy the battery can store.

How lithium cobalt oxide battery works is shown in below figure.

Lithium Cobalt Oxide Battery Reactions

What happens when you charge it,

Anode: LiCoO2 = Li1-xCoO2+xLi++xe-

Cathode: 6C+xLi++xe- = LixC6

What happens when you discharge

Anode: Li1-xCoO2+xLi＋+xe－=LiCoO2

Cathode: LixC6=6C+xLi++xe-

Applications:

Lithium cobaltate is the first generation of commercial anode materials. In decades of development, it can be considered as the most mature anode materials of lithium ion battery. It has been used in electronic equipment such as tablet and mobile phone, and also expand to different domain in recent years. Due to its good stability and consistency, high energy density and other advantages, lithium cobalt oxide battery has been gradually applied to medical equipment, instrumentation, emergency backup, special communication equipment, etc.

Lithium manganate oxide battery refers to the battery that uses lithium manganate oxide as an anode material. Its nominal voltage is 3.7V. It is the mainstream power battery at present. This kind of battery has ordinary energy density and cycling life. It has environmental protection and no patent limitation. But lithium manganate oxide is not very stable, easy to decompose gas, may lead to swell, and its high-temperature performance is poor. Lithium manganate oxide, whose chemical formula is LiMn2O4 (LCM), is one of the promising lithium ion anode materials. Compared with traditional anode materials such as lithium cobalt oxides, lithium manganate oxide has rich resources, low cost, no pollution, good safety and nice rate capability. It is an ideal anode material for power battery.

When a lithium manganate oxide battery is charged, lithium ions in the anode detach from the lattice, pass through the electrolyte to the cathode surface and embed into the graphite layer. When you discharge, the process is reversed. In charging and discharging process, lithium ions go between the anode and cathode, which is also known as the "rocking chair" battery.

Charging Process

When the battery is charged by the power source, the electron on the anode runs to the cathode from the external circuit. The lithium ion (Li+) goes into the electrolyte from the anode, passes through the small winding hole in the separator, reaches the cathode, and combines with the electrons that have already come over.

The reaction on the anode: LiMn2O4==Li1-xMn2O4+Xli++Xe(electron)

The reaction on the cathode: 6C+XLi+Xe==LixC6

Discharging Process

When the battery discharges, the electron on the cathode runs from the external circuit to the anode, and the lithium ion goes into the electrolyte from the cathode, passes through the small winding hole in the separator runs to the anode, and combines with the electrons that have already come over.

The reaction on the anode Li1-xMn2O4+xli++xe(electron)==LiMn2O4

The reaction on the cathode LixC6==6C+xLi+xe

Applications:

Lithium manganate oxide is one of the promising lithium ion anode materials. Compared with lithium cobalt oxide and other traditional anode materials, lithium manganate oxide has advantages of rich resources, low cost, no pollution, good safety and nice rate capability. It is an ideal anode material for power battery. Therefore, lithium battery electrode materials, especially the new-generation lithium manganate oxide anode materials, have great potential in the electric vehicle power battery market. Due to the low price and rich resources of lithium manganate oxide, it is easier to be produced than lithium cobalt oxides and lithium nickelate, which will make lithium ion battery enter a new era of development.

NMC battery in which the positive electrode material is composed of three materials of Nickel, cobalt, and manganese in a certain proportion and the negative electrode uses graphite. The voltage of the NMC battery is relatively high around 3.7 V.

One of the most successful li-ion cathode formulas developed to date is obtained by combining nickel, manganese, and cobalt. Lithium-Nickel-Manganese-Cobalt-Oxide (LiNiMnCoO2). It has become the go-to cathode powder to develop batteries for power tools, e-bikes and other electric powertrains. It delivers strong overall performance, excellent specific energy, and the lowest self-heating rate of all mainstream cathode powders, which makes it the preferred option for automotive batteries.

While NMC powder can refer to a variety of blends, the formula typically consists of 33% nickel, 33% manganese and 33% cobalt.

Crystal Structure of Nickel Cobalt Manganese Ternary Anode Material.

Ternary lithium battery refers to lithium battery that uses ternary materials of lithium nickel cobalt manganese oxide (LiNiMnCoO2, NMC) or lithium nickel cobalt aluminate (NCA) as anode material. Ternary means different proportions for different adjustments of nickel salt, cobalt salt and manganese salt as three different components. Lots of batteries have many different proportions of ternary materials. In terms of shape, ternary lithium batteries can be divided into soft-pack batteries, cylindrical batteries and square hard-shell batteries. Its nominal voltage can reach 3.6-3.8V. It has high energy density, high voltage platform, high tap density, long endurance range, large output power, excellent performance at low temperature, but poor stability at high temperature, and has high cost.

Chemical Equation of Charge and Discharge

Discharge: LiNixMnyCozO2→Li1-tNixMnyCozO2+tLi++te

Charge: Li1-tNixMnyCozO2+tLi++te→LiNixMnyCozO2

Application:

NMC is also used for mobile electronics such as mobile phones/smartphones, laptops in most pedelec batteries. For these applications, batteries with lithium cobalt oxide LCO were still used. Another application of NMC batteries are battery storage power stations.

Lithium Nickel Cobalt Aluminium Oxide (NCA):

The lithium nickel cobalt aluminium oxides (NCA) are a group of substances comprising metal oxides. Some of them are important due to their application in lithium ion batteries. NCAs are used as active material on the positive pole (which is the cathode when the battery is discharged).

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. summarizes the six key characteristics. NCA is a further development of lithium nickel oxide; adding aluminum gives the chemistry greater stability.

Lithium Iron Phosphate (LFP):

The lithium iron phosphate battery or LFP battery is a type of lithium-ion battery using lithium iron phosphate as the cathode material, and a graphitic carbon electrode with a metallic backing as the anode. The energy density of an LFP battery is lower than that of other common lithium ion battery types such as Nickel Manganese Cobalt (NMC) and Nickel Cobalt Aluminum (NCA), and also has a lower operating voltages LFP batteries are currently at 125 Wh/kg, up to possibly 160 Wh/kg with improved packing technology, while BYD's LFP batteries are at 150 Wh/kg, compared to over 300 Wh/kg for the highest NMC batteries.

Lithium iron phosphate as cathode material for rechargeable lithium batteries. 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. 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. Topping charge is applied to maintain full charge level and prevent sulfation on lead acid batteries.

Lithium Titanate (LTO):

The lithium-titanate or lithium-titanium-oxide (LTO) battery is a type of rechargeable battery which has the advantage of being faster to charge than other lithium-ion battery, but the disadvantage of having a much lower energy density. Lithium titanate battery is a lithium titanate used as a negative electrode material for lithium ion batteries. It can be combined with lithium manganate, ternary materials or lithium iron phosphate to form a 2.4V or 1.9V lithium ion secondary battery.

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. Illustrates the characteristics of the Li-titanate battery. Typical uses are electric powertrains, UPS and solar-powered street lighting.

Battery Abbrevation Anode Cathode Reaction at Anode Reaction at Cathode

1. LCO Lithium cobalt LiCoO2 LiC6 Li1-xCoO2+xLi++xe- 6C+xLi++xe-

oxide

2. LMO Lithium Manganese LiMn2O4 LiC6 Li1-xMn2O4+xli++xe 6C+xLi+xe

Oxide

3. NCA Lithium Nickel cobalt LiNiCoAlO2 LiC6 Li1-xNiCoAlO2+xLi++xe LiC6 xLi++xe-+C6

Aluminium oxide

4. NMC Lithium Nickel LiNiMnCoO2 LiC6 Li1-tNixMnyCozO2+tLi++te LiNixMnyCozO2

manganese cobalt

oxide

5. LFP Lithium Iron LiFePO4 LiC6 LixC6 XLi++xe-+C6 Li1-xFePO4+xLi++xe-

Phosphate

6. LTO Lithium Titanate Li2TiO3 Li4Ti5O12 Li4Ti5O12+3e-+3Li+ Li7Ti5O12

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

Lithium-ion batteries are used in most aspects of our everyday lives. Most devices like smartphones and laptops cannot operate without these batteries. Lithium-ion batteries have also become very important in the field of electromobility as it is now the battery of choice in most electric vehicles. Its high specific energy gives it an advantage over other batteries.

There are different types of lithium-ion batteries and the main difference between them lies in their cathode materials. Different kinds of lithium-ion batteries offer different features, with trade-offs between specific power, specific energy, safety, lifespan, cost, and performance.

The six lithium-ion battery types that we will be comparing are Lithium Cobalt Oxide, Lithium Manganese Oxide, Lithium Nickel Manganese Cobalt Oxide, Lithium Iron Phosphate, Lithium Nickel Cobalt Aluminum Oxide, and Lithium Titanate. Firstly, an understanding of the key terms below will allow for a simpler and easier comparison.

1.Lithium Cobalt Oxide has high specific energy as compared to the other batteries which make it the preferred choice for laptops and mobile phones. It also has a low cost and a moderate performance. However, it is highly unfavorable in all the other aspects when compared to the other lithium-ion batteries. It has low specific power, low safety, and a low lifespan.

2.Lithium Manganese Oxide has moderate specific power, moderate specific energy, and a moderate level of safety when compared to the other types of lithium-ion batteries. It has the added advantage of a low cost. The downsides are its low performance and low lifespan. It is usually used in medical devices and power tools.

3.Lithium Nickel Manganese Cobalt Oxide has two major advantages as compared to the other batteries. The first one is its high specific energy which makes it desirable in electric powertrains, electric vehicles, and electric bikes. The other is its low cost. It is moderate in terms of specific power, safety, lifespan, and performance when compared to the other lithium-ion batteries. It can be optimized to either have high specific power or high specific energy.

4.Lithium Iron Phosphate only has one major disadvantage when compared to other types of lithium-ion batteries and that is its low specific energy. Other than that, it has moderate to high ratings in all the other characteristics. It has high specific power, offers a high level of safety, has a high lifespan, and comes at a low cost. The performance of this battery is also moderate. It is often employed in electric motorcycles and other applications that require a long lifespan and a high level of safety.

5.Lithium Nickel Cobalt Aluminum Oxide offers one strong advantage as compared to the five other batteries and that is high specific energy. It is pretty moderate in the rest of the characteristics like performance, cost, specific power, and lifespan. The only downside to this battery type is its low level of safety. Its high specific energy and moderate lifespan make it a good candidate for electric powertrains.

6.Lithium Titanate offers high safety, high performance, and a high lifespan which are very important features every battery should have. Its specific energy is low compared to the five other lithium-ion batteries but it compensates for this with moderate specific power. The only major disadvantage of lithium titanate as compared to the other lithium-ion batteries is its extremely high cost. Another important feature of this battery worthy of mention is its remarkably fast recharge time. It can be used for storing solar energy and creating smart grids.

Comparision of All 6 Types of Lithium ion Batteries:

Item	LCO	LMO	NMC	NCA	LFP	LTO
chemical formula	LiCoO2	LiMn2O4	LiNiCoMnO2	LiNiCoAlO2	LiFePO4	Li2TiO3
theoretical capacity (mAh/g)	274	148	275	275	170	175
actual capacity(mAh/g)	140	120	160~220	180	150	160
tap density(g/cm3)	2.8	2.2	2.6	2.6	1	1.68
compaction density(g/cm3)	4.2	3	3.6	3.6	2.2	2.43
voltage platform(V)	3.7	4	3.5	3.5	3.3	2.4
cycling life	better	worse	ordinary	ordinary	good	better
transition metal	scarce	abundant	scarce	scarce	abundant	shortage
material costs	more expensive	cheap	expensive	expensive	cheap	expensive
environmental protection	contain cobalt	non-toxic	contain nickel and cobalt	contain nickel and cobalt	non-toxic	non-toxic
safety performance	bad	good	better	better	best	better

Specific energy: This defines the battery capacity in weight (Wh/kg). The capacity relates to the runtime. Products requiring long runtimes at moderate load are optimized for high specific energy.

Specific power: It's the ability to deliver a high current and indicates loading capability. Batteries for power tools are made for high specific power and come with a reduced specific energy.

Performance: This measures how well the battery works over a wide range of temperatures. Most batteries are sensitive to heat and cold and require climate control. Heat reduces life, and cold lowers performance temporarily.

Lifespan: This reflects cycle life and longevity and is related to factors such as temperature, depth of discharge, and load. Hot climates accelerate capacity loss. Cobalt blended lithium-ion batteries also usually have a graphite anode that limits the cycle life.

Safety: This relates to factors such as the thermal stability of the materials used in the batteries. The materials should have the ability to sustain high temperatures before becoming unstable. Instability can lead to thermal runaway in which flaming gases are vented. Fully charging the battery and keeping it beyond the designated age reduces safety.

Cost: Demand for electric vehicles has generally been lower than anticipated and this is mainly due to the cost of lithium-ion batteries. Hence cost is a huge factor when selecting the type of lithium-ion battery.