Lithium batteries are primary batteries that have metallic lithium as an anode. These types of batteries are also referred to as lithium-metal batteries.
They stand apart from other batteries in their high charge density (long life) and high cost per unit. Depending on the design and chemical compounds used, lithium cells can produce voltages from 1.5V (comparable to a zinc–carbon or alkaline battery) to about 3.7V. They do not need prolonged priming when new, one charge is sufficient. Lithium-ion batteries are in general low maintenance and a periodic discharge is not necessary.
TYPES OF LITHIUM ION BATTRIES
1. 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. Li-cobalt should not be charged and discharged at a current higher than it’s 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
- Low cost
- Poor Stability
- Effective for home use
- Relatively short life span,
- Low thermal stability and
- Limited load capabilities (specific power)
2. Lithium iron phosphate battery (LiFePO4 battery): It uses LiFePO4 as the cathode material, and a graphitic carbon electrode with a metallic backing as the anode. The specific capacity of LiFePO4 is higher than that of the related lithium cobalt oxide (LiCoO2) chemistry, but its energy density is less due to its lower operating voltage.
- Low cost
- Low toxicity
- Well-defined performance
- Long-term stability
- LiFePO4 batteries have a very constant discharge voltage. Voltage stays close to 3.2V during discharge until the cell is exhausted. This allows the cell to deliver virtually full power until it is discharged, and it can greatly simplify or even eliminate the need for voltage regulation circuitry.
- LiFePO4 has higher current or peak-power ratings than LiCoO2
- Many brands of LFPs, as well as cells within a given brand of LFP batteries, have a lower discharge rate than lead-acid or LiCoO2.
- LFP experiences much slower degradation
- The main drawback of LiFePO4 is its low electrical conductivity. Therefore, all the LiFePO4 cathodes under consideration are actually LiFePO4/C.
3. Lithium Manganese Oxide (LiMn2O4) — LMO: 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 are limited. Low internal cell resistance enables fast charging and high-current discharging.
- 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.
- Most Li-manganese batteries blend with lithium nickel manganese cobalt oxide (NMC) to improve the specific energy and prolong the life span.
- Relatively short cycle life and
- High capacity losses
- LMO batteries does not have a good power nor energy density
4. Lithium nickel manganese cobalt oxide-based batteries: The cathode of lithium nickel manganese cobalt oxide, LiNiMnCoO2 (NMC) is composed by cobalt, nickel and manganese. The most commonly used NMC composition contains equal amount of all three transition metals (i.e. Ni1/3Mn1/3Co1/3). The secret of NMC lies in combining nickel and manganese.
- NMC-based battery cells have high capacity,
- Good rate capability
- Can operate at high voltages.
- Poor Stability
5. 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
- Fast charged
- 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).
- Low specific energy
LITHIUM ION FOR SOLAR APPLICATION
The most commonly used lithium ion is the lithium iron phosphate (LiFePO4) battery, also called LFP battery (with “LFP” standing for “lithium Ferro phosphate”).
LiFePO4 batteries exhibit qualities that make them ideally suited for off-grid products where cost, safety, stability, and cycle life are primary requirements. They have lower energy density than competing Li-ion chemistries and a lower output voltage of 3.2V, but this is acceptable for most off-grid applications. Many successful off-grid products use LiFePO4 batteries.