Week 1 Understanding Different Battery Chemistry

1. Lithium-Ion Cells

Lithium-ion battery:

• Lithium Polymer batteries
• Lithium Cobalt Oxide (LiCoO₂)
• Lithium Manganese Oxide (LiMn₂O₄₎
• Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO₂)
• Lithium Iron Phosphate (LiFePO4)
• Lithium Nickel Cobalt Aluminum Oxide (LINICOAIO2)
• Lithium Titanate (Li2TiO3)

Types of Lithium-ion batteries:

• 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 its 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 the charge, the flow is from cathode to anode.

• Li-ion with manganese spinel was first published in the Materials Research Bulletin in 1983.
• In 1996, Moli Energy commercialized a Li-ion cell with lithium manganese oxide as cathode material.
• 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 is limited.
• Low internal cell resistance enables fast charging and high-current discharging.
• 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.
• This spinel structure, which is usually composed of diamond shapes connected into a lattice, appears after initial formation.

• 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 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 low specific energy. Combining the metals enhances each other strengths.

• This cell has a high discharge rate and, because phosphate (PO) can cope with high temperatures, the battery has good thermal stability, improving its safety.
• It's a good choice for things like electric vehicles and power tools, and for storing energy at power stations.
• It also has a long cycle life, meaning it can be discharged and charged many times.
• However, it has a lower energy density than a lithium cobalt oxide cell and a higher self-discharge rate.
• A lithium iron phosphate battery cell is similar to the lithium cobalt oxide cell. The anode is still graphite and the electrolyte is also much the same.
• The difference is that the lithium cobalt dioxide cathode has been replaced with the more stable um iron phosphate.
• In fact, no lithium or iron ions remain in the iron phosphate (FePO4) cathode of a fully charged cell. The lithium ions can intercalate into or out of the cathode material through well-defined tunnels in its structure without significantly altering the iron phosphate framework.

• 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, and the less flattering are safety and cost.
• NCA is a further development of lithium nickel oxide adding aluminum with it gives the chemistry greater stability.
• High energy and power densities, as well as a good life span, make NCA a candidate for EV powertrains.
• High cost and marginal safety are negatives.

• Batteries with lithium titanate anodes have been known since the 1980s.
• Li-titanate replaces the graphite in the anode of a typical lithium-ion battery and the material forms 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.
• LTO (commonly Li4T15012) 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

Table Properties:

2. Difference between the types of Lithium-ion battery