Wednesday, January 4, 2012

Batteries that have Li-ion Reliability

By James Steph


A new breed of functional, high-energy lithium batteries is changing the shape of next-generation products. Light and portable electronic devices, starting from notebook computers to handheld medical equipment to power tools, are benefiting from constant developments in energy density, together with from the popularity of thin-format laminate cells. For design and style engineers, the bottom line is that compact products together with extended charge times are more possible than ever.

Without a doubt, designers of consumer items are carrying out just that. Apple Inc. has notably previously used laminate-style lithium polymer power packs towards advantage in the Ipod and iPad, as well as in the paper-thin MacBook Air.

General Motors and Nissan are actually employing similar laminate-style technology on the Volt and Leaf, whereas Tesla Motors is utilizing 6,800 cylindrical lithium-ion batteries within its remarkably marketed Roadster. On the other hand, lithium is actually getting a major niche within the health care industry, whereby cart-based instruments are which gives way to portable screens.

Some of the keys to the recent rise of lithium-ion cells can be the consistent increase in capacity. Just lately, two.2Amp-hour cobalt-based lithium power packs were all the rage, however in the previous five-years; they're replaced by lithium cells that utilized nickel-manganese, and then nickel-aluminum. Throughout this march of success, battery capacities went up by to 2.6A-hr. and after that 2.9A-hr.

Around June, Panasonic presented the NCR18650A, a good lithium-ion cell that once again lengthens battery pack capacity, this time to 3.1A-hr. Later on this year, some battery power manufacturers would like to move to 3.4A-hr. Plus 4.0A-hr. batteries in the popular 18650 form aspect (cylindrical battery packs slightly bigger than an AA) might be released as soon as 2013, they assert.

Cylindrical cells push the envelope Engineers say the higher-energy breed of batteries is opening innovative applications in countless companies, but specifically in healthcare. There, clients are incorporating these items within portable ultrasound, portable o2 concentrators, and also portable work stations for the purpose of keeping track of clients. At the same time, a classical number of customers still is making use of lithium-ion as an alternative for nickel-metal hydride battery packs in notebook pc's, cell phones, digicams, and even power tools.

Laminate batteries make a comeback Even at the lithium-ion grouping, however, a sub-category is gaining momentum. Lithium polymer, another branch of lithium-ion which utilizes a flat laminate structure, is reaching a growing array of applications. "There's definitely a trend toward lithium polymer in portable devices because there's a race to make them all thinner," TI's Barsukov claims. "All of the newest, coolest gadgets out there, starting with Apple and Android devices, are using polymer because of the thin cells and the high energy density."

In fact, Apple's MacBook air measures 0.sixty seven " thick, thanks to some extent to its utilization of lithium polymer battery packs. Lithium polymer presents additional strengths. One of them:

Overall flexibility, that permits technical engineers to easily modify any design to adjust to an approved space Aspect ratio, which makes it better to create a large, flat cell Higher C-rate, that makes it possible to provide more current in a shorter time Lithium polymer provides many possibilities mainly because it uses a laminate structure that has an electrolyte which can range between liquid to gel to solid. Not like conventional lithium-ion cells, that happen to be included in a metal can, lithium polymer cells reside in a minimized foil bag, just like any potato chip bag. The multi-layered bag prevents fluids from moving into the battery and also avoids electrolytes from leaking out, however it offers an additional benefit: It's far lighter and also slimmer compared to cylindrical metal covering of an 18650. That, in turn, makes it possible to create a battery pack that is definitely comparable in form to a loose-leaf notebook.

What's more, lithium polymer cells offer you increased rates of discharge. The C-rate -- a parameter that describes the time it takes to fully discharge a battery -- is significantly better in polymer batteries than in cylindrical or even prismatic lithium-ion battery packs. Whereas traditional lithium-ion battery packs top out at C-rates of roughly 2, lithium polymer batteries is capable of having C-rates approaching 15 or more. The ability to discharge current on quicker rates translates to increased power for the apps.




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