Wednesday, December 7, 2022

Lithium-ion Batteries Portable Power Source for Portable Devices

Portable devices must have a power source as portable as possible. with ample energy density in a smaller size and lesser weight, lithium-ion batteries have made inroads in every portable device -- Shweta Dhadiwal Baid

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However, Laxman Soma, CEO, GSK Technologies, informs, “For the Rs 600-million business of mobile phones, every battery used is imported.” There is no Li-ion battery manufacturing being done in India. Soma suggest that if we really want to promote the use of hybrid electric vehicles, it’s necessary to have a Li-ion battery manufacturing set-up in India.

At one of the forums, Sharon Xiao, vice president, BAK, said, “Production of Li-ion batteries is a very difficult and complex process. It needs a very clean environment for manufacturing as any kind of contamination may affect the performance of the battery.”

In the recent past, we have experienced a lot of low-quality or duplicate Li-ion batteries being supplied which greatly harm the electronics. To facilitate the promotion of standards, use of original batteries and positive future outlook, India and China Lithium-ion Technology Forum was formed. The forum will primarily focus on technical specifications for mobile phones and Li-ion batteries.

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Comparing situation in India and China, Soma says, “The Chinese government has provided funding and fiscal incentives to Li-ion producers. It has also raised export tax rebates for Li-ion products. There is no funding or incentives available to the producers in India. The Indian government has to understand that there is a need for home-grown products to generate more business avenues.”


As regards the cost, Kandhari cites, “When it comes to battery pack, Li-ion batteries are the most cost-effective. For applications which demand higher voltage and current ratings, many batteries are packed together. For example, if the demand is 6V, you will need five 1.2V NiMH/NiCd batteries. The cost increases with the number of batteries. In the case of Li-ion, you need two 3.7V batteries to give you 7.4V. Thus the cost and size both are affected.” Also, the prices of nickel metal are increasing day-by-day.

Understanding their basics
A lot of people confuse between lithium and Li-ion batteries. These differ in that a lithium battery uses lithium in pure form, which raises its energy density considerably but makes it highly unstable too, while a Li-ion battery uses lithium compounds, which makes it much more stable but pack lesser energy density than lithium batteries.

Ali feels that battery and power management weren’t a concern for embedded engineers when it came to applications based on primary (non-rechargeable) electrical storage. But in devices using secondary (rechargeable) electrical storage, “Multiple user-interface and transactional requirements of the various components and modules, and the overall performance and operational expectations of play-time from a user’s perspective have made it compelling to understand the battery,” he says.

Based on their construction, Li-ion batteries can be classified as cylindrical and prismatic in shape. Further differentiation is in the inner anode and cathode material which could be layered in fla stacks or a long coiled layout. These formats reflectthe selection of the cell type based on the application. The classifiction is also done based on the type of electrolyte used (lithium-iron phosphate, lithium polymer) and the combination of rare elements (magnesium, nickel, cobalt, etc), which can vary in performance and price.

Ali says, “The refined nature of the chemicals used plays an important role.”

 [stextbox id=”info”]Some Li-ion battery vendors
Henan Huanyu
Maxell Panasonic

The major disadvantages of Li-ion batteries are combustion due to over-heating and leakage. Also, very deep discharge may result in short-circuit. To avoid such a situation, the Li-ion battery uses a fail-safe circuitry which shuts down the cell outside the safe range of 3-4.2V.

let your battery last longer
The key reason for the fading performance of a battery is the chemistry of the cell. Degradation is bound to happen in any chemical composition but it can certainly be controlled by improving the way the battery is used.

Michael Lin, material scientist, Quallion, shares, “The cell ages faster if you push it to more extreme states. If there is a higher state of charge and higher depth of discharge, which means you are operating your battery over a large voltage range, then the ageing is faster. In the case of high-power input/output, there is larger polarisation and the voltage becomes too high/too low while charging or discharging again, leading to faster ageing. Also, very high temperature leads to faster self-discharge, while very low temperature leads to large polarisation, which again degrades the performance of the cell.”

But ultimately, it depends on the cell chemistry that you use in your battery.



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