Home » Reference Library (Articles)
Return to Articles

Choosing between Lithium ION and Lithium Polymer Batteries

A brief article on how to choose between Lithium ION and Lithium Polymer Batteries

A Look Back

Lithium ion batteries have been commercially available since the early 1990s, possessing the highest energy density of all rechargeable battery chemistries and finding their way into almost every portable electronic device to date. In response to potential safety issues related to potential abuse events or conditions, battery pack designers and engineers have added several lines of defense with regard to battery safety. These include active circuits to maintain the battery voltage within a specific voltage window as well as short circuit protection, external PTCs to control the thermal environment of the battery pack and mechanical devices internal to the cell that disconnect the cell and arrest operation when abuse conditions occur.

In the early to mid-1990s, in response to safety considerations, as well as market pressures to make thinner and thinner cells that might not need active protection circuits, battery scientists looked for design techniques to mitigate the effects of overcharging or short circuits which could potentially harm consumers and users with shards of metal from a breeched cell can in the event of an explosion from abuse. Even though the many lines of defense were in place, continued attention to safety problems were at the forefront of engineer's minds. Lithium polymer technology provided an answer, whereby a gelled separator / electrolyte and a laminated aluminum bag substitute for a flooded electrolyte system and a sealed metal can. Less volume of volatile electrolyte was required for acceptable power rates and the bag would rupture a seal rather than violently release metal shards if over voltage or thermal runaway conditions occurred.

Polymer on the Rise

The adoption rate of lithium polymer technology in the marketplace since the early 1990s has been delayed by the instability of the supply chain as researchers struggled with manufacturing processes that combined plastics process technology with electrochemical engineering concepts, the need to manufacture the technology within reasonable economic limits and business models, and the requirement to keep pace with the rapidly growing performance of standard lithium ion chemistry. Early polymer cell and battery designs were very similar to that of conventional lithium ion batteries, offering no significant points of differentiation or enhanced product features and application engineers could not justify the tradeoffs with regard to increased design costs with the promised safety enhancements afforded by lithium polymer designs.

In the late 1990s, the combination of improving manufacturing yields, lower production costs, new and higher quality materials and a better understanding of cell design capabilities led the way to increasing the adoption rate of lithium polymer technology. Applications emerged, both in mass and niche markets, where new designs that utilized the thin, flat, form factor of lithium polymer justified design costs, market risk and consideration. Cell designs were better understood and could compete and surpass those afforded by conventional lithium ion batteries.

What's the Difference?

Lithium ion batteries consist of a cathode of lithiated metal oxide or phosphate, and a graphite anode separated by a polyethylene or polypropylene separator material in a non-aqueous electrolyte. When the battery is charged, lithium ions leave the cathode and are intercalated (inserted) into the layered structure of the graphite. As the battery discharges, lithium ions leave the anode and return to the cathode, while electrons travel in the opposite direction, completing the circuit.

Lithium polymer batteries have the same common electrochemistry as conventional lithium ion batteries - they have a lithiated oxide cathode and a graphite anode held together in a binder matrix of polyvinlydiene fluoride and coated and/or laminated to a current collector grid. However, they contain a highly porous separator, which converts to a gel when a minimum amount of electrolyte is added to operate the cell. Lithium polymer technology uses stacked plate cell architecture, as opposed to a wound "jelly roll" found in conventional lithium ion cells, which means that they consist of die-cut anode and cathode plates that are about the size of the battery and are stacked on top of each other like a deck of cards, with the plates connected in parallel.

Lithium polymer batteries have comparable energy density to lithium ion batteries and are achieving cost parity. The cells are sealed in a plastic aluminum laminate, so if the battery sees an overcharge condition, the seal ruptures and vents any gases due to electrolyte oxidation and the cell shuts down rather than having steel or aluminum casings fragment, as in the case of lithium ion batteries that may result in metal shards.

How to Choose

When our Applications Engineers receive inquiries from customers looking for small rechargeable batteries, they guide them through a number of questions in order make a sound recommendation.

First, they need to understand the application. Is it commercial, industrial, military or consumer? This invariably leads to sizing questions, mechanical constraints, and packaging parameters. From here, electrical needs are addressed including voltage, capacity and drain. And finally, yearly quantities and cost structures are discussed at very introductory levels.

From this round of discussions and guidance from the customer, a thoughtful recommendation can be made.

Generally, battery cavity restrictions and cost structures built into the product or application determine whether or not Lithium ion or Lithium polymer batteries are recommended. If an application needs a very thin battery, typically less than 4 or 5mm, lithium polymer is recommended as it can be manufactured to such degrees of thinness that can't be matched by Lithium ion. If the application's battery cavity is a bit more forgiving, then Lithium ion is typically recommended largely due it being less expensive to manufacture.

Other factors, of course, will play into whether or not Lithium ion or Lithium polymer is recommended such as weight and customization needs. But on a very general level, thickness and cost structures play a very large role in determining which battery type is right for you.

810-401 HP2-B115 070-461 70-480 HP2-H35 MB5-705 CCA-500 70-410 70-488 70-461 MB5-705 200-120 70-486 70-411 70-480 70-346 70-462 70-347 70-412 70-483 220-801 MB2-708 070-488 C4040-252 70-410 200-120 C4040-250 70-486 70-461 MB5-705 70-488 70-486 70-411 70-480 70-346 70-462 70-347 70-412 70-483 70-417 MB2-702 640-911 74-335 700-505 70-414 810-401 700-501 CCA-500 N10-005 70-243 E10-001 VCP-550 1Z0-062 70-466 200-101 70-489 MB2-701 640-864 A00-211 700-501 CCA-500 N10-005 70-243 E10-001 VCP-550 1Z0-062 70-466 200-101 70-489 MB2-701 640-864 70-534 98-349 70-341 300-208 400-051 98-365 HP5-B04D PMP 642-874 70-332 PRINCE2 HP5-B04D PMP 642-874 70-332 PRINCE2 1Z0-051 1Z0-052 1Z0-053 312-49v8 74-343 74-697 98-367 HP0-J34 SCNS 074-679 70-443 000-216 351-080 CLO-001 C2140-137 070-299 9L0-510 642-416 A2180-183 MB3-701 MB3-859 MB3-860 MB3-861 MB3-862 MB4-198 MB4-211 MB4-212 MB4-213 MB4-217 MB4-218 MB4-219 MB4-348 MB4-349 C4040-252 MB5-705 70-410 C4040-250 70-461 200-120 70-486 810-401 70-483 70-417 640-554 70-488 220-801 300-101 70-467 CISSP SY0-401 MB2-702 640-911 74-335 700-505 70-414 810-401 700-501 CCA-500 N10-005 70-486 70-410 70-488 70-461 MB5-705 200-120 70-486 70-410 70-488 70-461 MB5-705 200-120 70-486 70-411 70-480 70-346 70-462 70-347 70-412 70-483 70-417 MB2-703 70-331 220-802 C4040-252 C_TADM51_731 1Z0-061 70-487 400-101 CCD-410 100-101 MB2-700 1Z0-060 70-463 EX200 C4040-250 300-115 640-554 70-533
©2017 House of Batteries - 10910 Talbert Ave - Fountain Valley, California 92708
Phone: (800) 432-3385 / (714) 962-7600 - Fax: (714) 962-7644
 
Terms & Conditions | Privacy Policy | Map to our Facility | Employment Opportunities | Site Map
Site Credits: Ecreativeworks