Pioneering work of the lithium battery began in 1912 under G.N. Lewis, but it was not until the early 1970s that the first non-rechargeable lithium batteries became commercially available. Attempts to develop rechargeable lithium batteries followed in the 1980s but failed because of instabilities in the metallic lithium used as anode material. (The metal-lithium battery uses lithium as anode; Li-ion uses graphite as anode and active materials in the cathode.) The key to the superior specific energy is the high cell voltage of 3.60V. Improvements in the active materials and electrolytes have the potential to further boost the energy density. Load characteristics are good and the flat discharge curve offers effective utilization of the stored energy in a desirable and flat voltage spectrum of 3.70–2.80V/cell. In 1994, the cost to manufacture Li-ion in the 18650 cylindrical cell was over US$10 and the capacity was 1,100mAh. In 2001, the price dropped to below $3 while the capacity rose to 1,900mAh. Today, high energy-dense 18650 cells deliver over 3,000mAh and the costs are dropping. Cost reduction, increased specific energy and the absence of toxic material paved the road to make Li-ion the universally accepted battery for portable applications, heavy industries, electric powertrains and satellites. The 18650 measures 18mm in diameter and 65mm in length. Li-ion is a low-maintenance battery, an advantage that most other chemistries cannot claim. The battery has no memory and does not need exercising (deliberate full discharge) to keep it in good shape. Self-discharge is less than half that of nickel-based systems and this helps the fuel gauge applications. The nominal cell voltage of 3.60V can directly power mobile phones, tablets and digital cameras, offering simplifications and cost reductions over multi-cell designs. The drawbacks are the need for protection circuits to prevent abuse, as well as high price. Cathode Materials for Lithium-ion Batteries Cathode materials are the main component of Li-ion batteries; they determine the energy density of a cell through cell voltage and / or capacity. Lithium ion batteries are typically based on intercalation / deintercallation compounds, where lithium ions provided by the cathode are inserted into the host lattice (anode) during charge and extracted during discharge, with a minimal structural change in the host material. The choice of cathode material with a particular chemistry depends on various factors, including cell voltage, capacity, energy and power capabilities, cycle life, and temperature of operation.
To meet the demands in portable electronic devices, electric vehicles and stationary energy storage, it is necessary to prepare advanced lithium ion batteries (LIBs) with high energy density and fast charge and discharge capabilities. Cathode materials, which account for 40%–50% of the cost of a whole battery, play a decisive role in cell voltage and capacity. Moreover, the performances of the cathodes are also balanced by many other aspects, including cycle life, rate capability, safety, costs, and environmental benignity. Unfortunately, none of the currently available cathode materials (e.g. LiFePO4, LiNixCoyMn1−x−yO2 layered oxides and Li-rich layered oxides) can get all the quests in a single cell. The electrochemical performances of a cathode are closely connected with its structural features, such as the porosities, morphologies and specifically exposed surfaces, which can be tuned by delicate designs. Here, we review our work on the rational design and delicate preparation of a series of cathode materials with controllable microstructures. We reveal the synergistic effects of both reaction and mass transfer on the formation of these meso-scale structures and the improved electrochemical performances of the cathode materials. The review will provide a scientific basis for the large-scale production of meso-scale structured cathode materials, and lay theoretical and experimental foundation for the application of cathode materials in next-generation LIBs.
Lithium-ion is named for its active materials; the words are either written in full or shortened by their chemical symbols. A series of letters and numbers strung together can be hard to remember and even harder to pronounce, and battery chemistries are also identified in abbreviated letters. For example, lithium cobalt oxide, one of the most common Li-ions, has the chemical symbols LiCoO2 and the abbreviation LCO. For reasons of simplicity, the short form Li-cobalt can also be used for this battery. Cobalt is the main active material that gives this battery character. Other Li-ion chemistries are given similar short-form names. This section lists six of the most common Li-ions. All readings are average estimates at time of writing. Lithium-ion batteries can be designed for optimal capacity with the drawback of limited loading, slow charging and reduced longevity. An industrial battery may have a moderate Ah rating but the focus in on durability
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. The drawback of Li-cobalt is a relatively short life span, low thermal stability and limited load capabilities (specific power). Like other cobalt-blended Li-ion, Li-cobalt has a graphite anode that limits the cycle life by a changing solid electrolyte interface (SEI), thickening on the anode and lithium plating while fast charging and charging at low temperature. Newer systems include nickel, manganese and/or aluminum to improve longevity, loading capabilities and cost. 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. (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 for the Energy Cell.
Lithium Cobalt Oxide: 
LiCoO2 cathode (~60% Co), graphite anode Short form: 
LCO or Li-cobalt. Voltages 
3.60V nominal; typical operating range 3.0–4.2V/cell Specific energy (capacity) 
150–200Wh/kg. Specialty cells provide up to 240Wh/kg. Charge (C-rate) 
0.7–1C, charges to 4.20V (most cells); 3h charge typical. 
Charge current above 1C shortens battery life. Discharge (C-rate) 
1C; 2.50V cut off. Discharge current above 1C shortens battery life. Cycle life 
500–1000, related to depth of discharge, load, temperature Thermal runaway 
150°C (302°F). Full charge promotes thermal runaway
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 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 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.
Lithium Manganese Oxide: LiMn2O4 cathode. graphite anode Short form: LMO Li-manganese (spinel structure) Voltages 3.70V (3.80V) nominal; typical operating range 3.0–4.2V/cell Specific energy (capacity) 100–150Wh/kg Charge (C-rate) 0.7–1C typical, 3C maximum, charges to 4.20V (most cells) Discharge (C-rate) 1C; 10C possible with some cells, 30C pulse (5s), 2.50V cut-off Cycle life 300–700 (related to depth of discharge, temperature) Thermal runaway 250°C (482°F) typical. High charge promotes thermal runaway
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 Power Cells. For example, NMC in an 18650 cell for moderate load condition has a capacity of about 2,800mAh and can deliver 4A to 5A; NMC in the same cell optimized for specific power has a capacity of only about 2,000mAh but delivers a continuous discharge current of 20A. A silicon-based anode will go to 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 a low specific energy. Combining the metals enhances each other strengths.
Lithium Nickel Manganese Cobalt Oxide: LiNiMnCoO2. cathode, graphite anode Short form: NMC (NCM, CMN, CNM, MNC, MCN similar with different metal combinations) Voltages 3.60V, 3.70V nominal; typical operating range 3.0–4.2V/cell, or higher Specific energy (capacity) 150–220Wh/kg Charge (C-rate) 0.7–1C, charges to 4.20V, some go to 4.30V; 3h charge typical. Charge current above 1C shortens battery life. Discharge (C-rate) 1C; 2C possible on some cells; 2.50V cut-off Cycle life 1000–2000 (related to depth of discharge, temperature) Thermal runaway 210°C (410°F) typical. High charge promotes thermal runaway
In 1996, the University of Texas (and other contributors) discovered 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. (See BU-808: How to Prolong Lithium-based Batteries). 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. This can be mitigated by buying high quality cells and/or using sophisticated control electronics, both of which increase the cost of the pack. Cleanliness in manufacturing is of importance for longevity. There is no tolerance for moisture, lest the battery will only deliver 50 cycles. Figure 9 summarizes the attributes of Li-phosphate.
Lithium Iron Phosphate: LiFePO4 cathode, graphite anode Short form: LFP or Li-phosphate. LIP is also common. Voltages 3.20, 3.30V nominal; typical operating range 2.5–3.65V/cell Specific energy (capacity) 90–120Wh/kg Charge (C-rate) 1C typical, charges to 3.65V; 3h charge time typical Discharge (C-rate) 1C, 25C on some cells; 40A pulse (2s); 2.50V cut-off (lower that 2V causes damage) Cycle life 2000 and higher (related to depth of discharge, temperature) Thermal runaway 270°C (518°F) Very safe battery even if fully charged
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. NCA is a further development of lithium nickel oxide; adding aluminum gives the chemistry greater stability.
Lithium Nickel Cobalt Aluminum Oxide: LiNiCoAlO2 cathode (~9% Co), graphite anode Short form: NCA or Li-aluminum. Voltages 3.60V nominal; typical operating range 3.0–4.2V/cell Specific energy (capacity) 200-260Wh/kg; 300Wh/kg predictable Charge (C-rate) 0.7C, charges to 4.20V (most cells), 3h charge typical, fast charge possible with some cells Discharge (C-rate) 1C typical; 3.00V cut-off; high discharge rate shortens battery life Cycle life 500 (related to depth of discharge, temperature) Thermal runaway 150°C (302°F) typical, High charge promotes thermal runaway

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