Lithium-Based Batteries : An Engineering Marvel Part 1

14 October 2014

Lithium-Based Batteries : An Engineering Marvel Part 1

G.N Lewis is the person credited with the earliest work on the lithium-based batteries in 1912 though it was only until the early 1970’s when the first set of lithium based batteries became available. There were numerous attempts to make rechargeable variants of the lithium battery in the 1980’s but they all failed due to the instability caused by the use of lithium as anode material.

Lithium is known as the lightest metal, has great electrochemical potential and is known to have the largest amount of specific energy per unit weight. Hence rechargeable batteries which use Lithium at the battery anode could in principal provide a great amount of energy. But over use these anodes could cause a short and the increase in temperature so caused could result in thermal runaway and make the whole apparatus highly volatile. Due the instability associated with using lithium in this form research was shifted to developing lithium ion batteries.

Though they have lower levels of specific energy as compared to lithium metal, they are much safer to operate with. Sony was a pioneer in this field and was the first to introduce a fully working rechargeable battery based on lithium ion technology. The actual specific-energy of Li-ion is about twice that of a NiCd based system and the higher nominal voltage of 3.60V is a major contributor to this. The nickel system has a measly 1.20V nominal cell voltage. Also further improvement can be made to the active constituents of the electrode to increase the energy density.

Lithium-based batteries provide good load characteristics and their flat discharge curve means that they offers proper utilization of energy in the desired range of 2.80 to 3.7 V per cell. The costs of manufacturing Li-ion based batteries have constantly dropped over the last twenty years and batteries with capacities of 3100 mAh and above are easily available at affordable rates. The reductions in costs, high levels of specific-energy and the absence of any toxic materials have resulted in Lithium based batteries becoming the standard energy source for portable devices. Initially its market had been limited to just the consumer industry but now it is becoming the power source of choice for heavy industries such as power-trains in vehicles etc.

By the year 2009 about 40 percent of the total revenue in batteries was Li-ion based. Lithium-based batteries are essentially low maintenance which cannot be said of all its competitors. The battery doesn’t have any memory and users do not have to employ the deliberate full discharge method to keep it in working condition. The Self discharge of these batteries is below half the levels of the nickel based ones. The nominal voltage of Li-ion battery which comes to 3.60V can easily power digital cameras and cell phones, thus avoiding complex multi-cell designs. The slight drawback of Lithium-based battery is the need for customized circuits for protection to be in place to prevent any abuse.