It was not until the early 1970s the Li-Polymer equipment battery packs became commercially available. Efforts to develop rechargeable lithium batteries followed in the 1980s although the endeavor failed due to instabilities in the metallic lithium used as anode material.
Lithium is the lightest of metals, provides the greatest electrochemical potential and offers the largest specific energy per weight. Rechargeable batteries with lithium metal in the anode (negative electrodes) could provide extraordinarily high energy densities, however, cycling produced unwanted dendrites in the anode that could penetrate the separator and cause an electric short. The cell temperature would rise quickly and approaches the melting reason for lithium, causing thermal runaway, often known as “venting with flame.”
The inherent instability of lithium metal, especially during charging, shifted research into a non-metallic solution using lithium ions. Although lower in specific energy than lithium-metal, Li-ion is protected, provided cell manufacturers and battery packers follow safety measures to keep voltage and currents to secure levels. In 1991, Sony commercialized the 1st Li-ion battery, now this chemistry has become the most promising and fastest growing on the market. Meanwhile, research continues to build a safe metallic lithium battery in the hope so it will be safe.
In 1994, it might cost more than $10 to manufacture Li-ion in the 18650* cylindrical cell delivering a capacity of 1,100mAh. In 2001, the retail price dropped to $2 as well as the capacity rose to 1,900mAh. Today, high energy-dense 18650 cells deliver over 3,000mAh and the costs have dropped further. Cost reduction, increase in specific energy and the lack of toxic material paved the road to make Li-ion the universally acceptable battery for portable application, first inside the consumer industry and now increasingly also in heavy industry, including electric powertrains for vehicles.
During 2009, roughly 38 percent of most Custom medical equipment batteries by revenue were Li-ion. Li-ion can be a low-maintenance battery, a benefit many other chemistries cannot claim. The battery has no memory and will not need exercising to hold in shape. Self-discharge is less than half compared to nickel-based systems. This may cause Li-ion well suited for fuel gauge applications. The nominal cell voltage of three.6V can power mobile devices and digital cameras directly, offering simplifications and price reductions over multi-cell designs. The drawback has become the high price, but this leveling out, particularly in the buyer market.
Like the lead- and nickel-based architecture, lithium-ion works with a cathode (positive electrode), an anode (negative electrode) and electrolyte as conductor. The cathode is really a metal oxide along with the anode contains porous carbon. During discharge, the ions flow from your anode towards the cathode throughout the electrolyte and separator; charge reverses the direction along with the ions flow from your cathode towards the anode. Figure 1 illustrates this process.
Once the cell charges and discharges, ions shuttle between cathode (positive electrode) and anode (negative electrode). On discharge, the anode undergoes oxidation, or reduction in electrons, and also the cathode sees a reduction, or even a gain of electrons. Charge reverses the movement.
All materials in a battery have a very theoretical specific energy, along with the answer to high capacity and superior power delivery lies primarily inside the cathode. For the past ten years or so, the cathode has characterized the Li-ion battery. Common cathode material are Lithium Cobalt Oxide (or Lithium Cobaltate), Lithium Manganese Oxide (also called spinel or Lithium Manganate), Lithium Iron Phosphate, in addition to Lithium Nickel Manganese Cobalt (or NMC)** and Lithium Nickel Cobalt Aluminum Oxide (or NCA).
Sony’s original lithium-ion battery used coke as being the anode (coal product), and also, since 1997 most ODM RC toys Li-Po battery packs use graphite to obtain a flatter discharge curve. Developments also occur around the anode and plenty of additives are now being tried, including silicon-based alloys. Silicon achieves a twenty to thirty percent increase in specific energy at the cost of lower load currents and reduced cycle life. Nano-structured lithium-titanate as anode additive shows promising cycle life, good load capabilities, excellent low-temperature performance and superior safety, nevertheless the specific energy is low.
Mixing cathode and anode material allows manufacturers to boost intrinsic qualities; however, an enhancement in just one area may compromise another thing. Battery makers can, for instance, optimize specific energy (capacity) for extended runtime, increase specific power for improved current loading, extend service life for better longevity, and enhance safety for strenuous environmental exposure, but, the drawback on higher capacity is reduced loading; optimization 23dexjpky high current handling lowers the actual energy, and making it a rugged cell for long life and improved safety increases battery size and increases the cost caused by a thicker separator. The separator is said to be the most costly a part of a battery.
Table 2 summarizes the characteristics of Li-ion with some other cathode material. The table limits the chemistries to the four most frequently used lithium-ion systems and applies the short form to describe them. NMC stands for nickel-manganese-cobalt, a chemistry which is fairly new and can be tailored for top capacity or high current loading. Lithium-ion-polymer will not be mentioned as this is not really a unique chemistry and simply differs in construction. Li-polymer can be made in different chemistries along with the most generally used format is Li-cobalt.