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What other Lithium Batteries are there and what are their benefits?

Lithium Cobalt Oxide(LiCoO2)

Its high specific energy makes Li-cobalt the popular choice for cell 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). Figure 1 summarizes the attributes of Li-phosphate.

  • Figure 2: Li-cobalt structure

  • The cathode has a layered structure. During discharge the lithium ions move from the anode to the cathode; on charge the flow is from anode to cathode.

  • (Source: Cadex via Battery University Apr 21, 2015)​

Li-cobalt cannot be charged and discharged at a current higher than its 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 1920mA. See BU-402: What is C-rate). The mandatory battery protection circuit limits the charge and discharge rate to a safe level of about 1C.

The hexagonal spider graphic (Figure 3) summarizes the performance of Li-cobalt in terms of specific energy or capacity; specific power or the ability to deliver high current; safety or the chances of venting with flame if abused; performance at hot and cold temperatures; life span reflecting cycle life and longevity; and cost. These spider webs provide do not include all attributes and others of interest are levels of toxicity, fast-charge capabilities, self-discharge and shelf life.

  • Figure 3: Snapshot of an average Li-cobalt battery

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

  • (Source: Cadex via Battery University Apr 21, 2015)

Summary Table

Table 2: Characteristics of Lithium Cobalt Oxide (Source: Battery University Apr 21 2015)

Lithium Manganese Oxide (LiMn2O4)

Lithium insertion in manganese spinels was first published in the Materials Research Bulletin in 1983. In 1996, Moli Energy commercialized a Li-ion cell with lithium manganese oxide as a cathode material. The architecture forms a three-dimensional spinel structure that improves ion flow on the electrode, which results in lower internal resistance and improves 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 promotes fast charging and high-current discharging. In an 18650 package, Li-manganese can be discharged at currents of 20–30A with moderate heat buildup. 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.

Figure 4 shows the crystalline formation of the cathode in a three-dimensional framework. This spinel structure, which is usually composed of diamond shapes connected into a lattice, appears after initial formation.

  • Figure 4: Li-manganese structure

  • The cathode crystalline formation of lithium manganese oxide has a three-dimensional framework structure that appears after initial formation. Spinel provides low resistance but has a more moderate specific energy than cobalt.

  • (Source: Cadex via Battery University Apr 21, 2015)

Li-manganese has a capacity that is roughly one-third lower compared to Li-cobalt but the battery still holds about 50 percent more energy than nickel-based chemistries. 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 1,100mAh; the high-capacity version is 1,500mAh but has a reduced service life.

Figure 5 shows the spider web of a typical Li-manganese battery. In this chart, all characteristics are marginal; however, newer designs have improved in terms of specific power, safety and life span.

  • Figure 5: Snapshot of a pure Li-manganese battery

  • Most modern manganese-based Li-ion systems include a blend of nickel and cobalt. Typical designations are LMO/NMC for lithium manages oxide/nickel-manganese-cobalt.

  • (Source BCG research via Battery University, Apr 21 2015)

Summary Table

Table 3: Characteristics of Lithium Manganese Oxide (Source: Battery University Apr 21 2015)

Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2 or NMC)

Leading battery manufacturers focus on a cathode combination of nickel-manganese-cobalt (NMC). Similar to Li-manganese, these systems can be tailored for high specific energy or high specific power, but not both. For example, NMC in an 18650 cell for moderate load condition has a capacity of about 2,800mAh and can deliver 4–5A; NMC in the same cell optimized for specific power has a capacity of only about 2,000mWh but delivers a continuous discharge current of 20A. A silicon-based anode will go to 4,000mAh but at reduced loading and shorter cycle life.

The secret of NMC lies in combining nickel and manganese. An analogy of this is table salt, in which the main ingredients of 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 is the battery of choice for power tools, e-bikes and other electric powertrains. The cathode combination of typically one-third nickel, one-third manganese and one-third cobalt offers a unique blend that also lowers raw material cost due to reduced cobalt content. Other combinations, such as NCM, CMN, CNM, MNC and MCN are also being offered in which the metal content of the cathode deviates from the 1/3-1/3-1/3 formula. Manufacturers keep the exact ratio a well-guarded secret. Figure 6 demonstrates the characteristics of the NMC.

  • Figure 6: Snapshot of NMC

  • 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.

  • (Source BCG research via Battery University, Apr 21 2015)

Summary Table

Table 4: Characteristics of Lithium Nickel Manganese Cobalt Oxide (NMC) (Source: Battery University Apr 21 2015)

Lithium Nickel Cobalt Aluminum Oxide (LiNiCoAlO2)

Lithium Nickel Cobalt Aluminum Oxide battery, or NCA, has been around since 1999 for special application and shares similarity with NMC by offering high specific energy and reasonably good specific power and a long life span. These attribute made Elon Musk choose NCA for the Tesla Electric Vehicles. However these batteries have not achieved the same safety standards and are reasonably expensive at this time. Figure 7 demonstrates the strong points against areas for further development. NCA is a further development of lithium nickel oxide; adding aluminum gives the chemistry greater stability.

  • Figure 7: Snapshot of NCA

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

  • (Source: Cadex via Battery University Apr 21, 2015)

Summary Table

Table 5: Characteristics of Lithium Nickel Cobalt Aluminum Oxide (Source: Battery University Apr 21 2015)

Lithium Titanate (Li4Ti5O12)

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 into a spinel structure. The cathode is graphite and resembles the architecture of a typical lithium-metal battery. 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). However, the battery is expensive and at 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. Figure 8 illustrates the characteristics of the Li-titanate battery. Typical uses are electric powertrains and UPS.

  • Figure 8: Snapshot of Li-titanate

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

  • (Source BCG research via Battery University, Apr 21 2015)

Summary Table

Table 6: Characteristics of Lithium Titanate (Source: Battery University Apr 21 2015)

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