A Beginner's Guide to Buying Li-Ion Batteries

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Battery technology is continually developing, and one highly interesting type of battery in this development is the lithium-ion battery (Li-ion battery). They are most popular for use in portable electronics. Li-ion batteries are also developing their uses in electric vehicle, military, and aerospace applications.

About Li-ion Batteries

The three primary working components of a Li-ion battery are the negative electrode, positive electrode, and the electrolyte. When the battery charges, an over-voltage than that produced by the battery is applied by an external electrical power source, (for example, the charging circuit) forcing the current in a reversed direction. The lithium ions then migrate from the positive electrode to the negative electrode and become embedded. This process is also known as intercalation. During discharge, this is reversed, as the lithium ions make the current pass from the negative electrode to the positive electrode.

Lit-ion Battery Energy Density and Charge

Li-ion batteries are highly popular because they have high energy densities, (amount of energy) no memory effect, and very little loss of charge when not in use. Memory effect refers to an effect observed in batteries that causes them to hold less charge. It describes a specific situation in which batteries gradually lose their maximum energy capacity if they are repeatedly recharged after being only partially discharged. The battery appears to "remember" the smaller capacity. The memory effect occurs in rechargeable NiCD batteries. NiMH batteries can lose up to 40 per cent of their charge within a month, while Li-ion batteries lose up to 5 per cent. However, Li-ion batteries do have their faults. They have a higher initial cost, and cannot be charged using standard battery chargers. Specific chargers must be bought and this can be expensive as well as inconvenient. They are also known to have had safety problems in the past. Li-ion batteries do not come in 'convenient' sizes such as AA, AAA, C, or D and they will usually only last 2 or 3 years from the date of manufacture; whether the battery is used or not. Fortunately, researchers are working to develop new improvements to traditional Li-ion battery technology, focusing on durability, energy density, cost, and intrinsic safety.

Choosing Li-ion Batteries

Like every other product, Li-ion batteries come in a variety of sizes and formats for the consumer to choose from. Consider uses, materials, costs, and brands before buying. Li-ion batteries are available in a range of formats, which can be divided into four general groups.


Small cylindrical

Large cylindrical




Solid body without any terminals

Solid body with large, threaded terminals

Soft, and usually quite small, flat body

Plastic case which is semi-hard with large, threaded terminals

There are also a number of materials Li-ion batteries can be made from, and different materials have unique target applications and benefits. Take a look at the following table.

Technology (materials used)

Target application


Manganese spinel (LMO)

Hybrid electric vehicle, cell phone, laptop

durability, cost

Lithium iron phosphate

Power tools, (such as drills) aviation products, automotive hybrid systems

moderate density

Lithium nickel manganese cobalt (NMC)


good density and output, safe to use



good power, safe to use

Lithium iron fluorophosphate


durability, affordable cost

Lithium air


density, safe to use

5 per cent Vanadium-doped Lithium iron phosphate olivine



Lithium purpurin


organic material, inexpensive cost for production
90 mA•h/g after 50 charge/discharge cycles

Lithium Manganese Di-oxide on porous Tin

Automotive, electronics

high energy density and power, rapid charge time when using microstructured porous tin

Lithium titanate battery

Automotive, electrical grid, bus

low charge time, good durability (up to 20 years and approx. 9000 cycles), safe to handle, operates at low and high temperatures

Lithium vanadium oxide


density of 745Wh/l

Cobalt-oxide nanowires from genetically modified virus


density, thickness

3D porous particles made up of curved 2D nanolayers

High energy batteries for electronics and electrical vehicles

specific capacity of more than 2000 mA•h/g, good efficiency, fast, inexpensive synthesis

Iron-phosphate nanowires from genetically modified virus


density, thickness

Silicon/titanium dioxide composite nanowires from genetically modified tobacco virus

Explosive detection sensors, biomimetic structures, water-repellent surfaces, micro/nanoscale heat pipes

density, short charge time

Silicon whisker on carbon nanofiber composite

Portable electronics, electrical vehicles, electrical grid

high capacity, short charge time, good cycle life

Nanosised wires on stainless steel

Wireless sensors networks

limited density, and issues with durability (cracks in wire)

Metal hydrides


density of 1480 mA•h/g

Silicon nanotubes/nanospheres confined within rigid carbon outer shells

Stable high energy batteries for electronic devices including cell phones, laptops, sensors, and also electrical vehicles

specific capacity of 2400 mA•h/g, very high efficiency and very good stability

Silicon nanopowder in conductive polymer binder

Automotive and electronics

compatible with commercial silicon, high capacity and good cycling characteristics

Silicon oxide-coated double-walled silicon nanotubes

Automotive and electronics

good durability, thousands of charge cycles



power density of 1500 watt-hours/kg. (note- non-rechargeable)



power density of up to 10,000 mA•h/g.

Electro-plated tin

Consumer electronics

cheaper price. Three times capacity compared to conventional Li-ion

Solid-state plated copper antimonide nanowire

Consumer electronics

less charging time and more energy density. 750 charging cycles.

Boron-doped silicon nanospheres


less charging time and better density.

Hard carbon

Consumer electronics

30 per cent more storage capacity compared to graphite



durability, safety (limited density)






operation at low and high temperature

Nickel/Tin on porous Nickel

Automative, electronics

energy density and power using microstructured metal as the substrate for thin film.

Lithium imide

Consumer electronics

Reduced thermal expansion. 750 - 800 charging cycles with over 80 per cent of original capacity.

Different Li-ion batteries or individual cells may be called a variety of names. The following table examines the names, typical capacities, dimensions and related sizes of different Li-ion batteries.

Common name of cell

Other names

Typical capacity (mAh)

Dimensions (max) dia x l. (mm)

Related cell sizes




10 x 18





10 x 28





10 x 44

Same size as AAA cell.




14 x 25

Same size as 1/2 AA cell.




14 x 50

Same size as AA cell.




14 x 65





15 x 27

Substitute for CR2 primary lithium. 3V.




16 x 34

Alternate substitute for CR123A primary lithium. Unprotected. (16 × 36, some protected versions)


17340, R123, RCR123, 2/3A, Tenergy 30200


17 x 34.5

Same size as, and substitute for, CR123 primary lithium for cameras and flashlights. Size 2/3A. Protected version.




17.3 x 50

The same size as an A cell, and 1.5 times the length of a CR123A.




17 x 67

2 times the length of a standard CR123A.




18 x 35 (nominal)





18.3 x 49.8

About the same size as an A cell, but larger diameter.




18.6 x 65.2

This cell type is used in many laptop batteries and the Tesla Roadster and LED flashlights.


Protected 18650


19 x 67

Correct designation of 'protected 18650'




19.3 x 49.2

About the same size as a C cell.




19.5 x 65.4





32 x 61.9

About the same size as a D cell.

Find Li-ion Batteries on eBay

Go to the eBay homepage and begin by opening the All Categories tab and clicking on the link for Electronics, followed by Batteries, Chargers. From this page, click on Batteries. This will then open up a few more options underneath, including Rechargeable. Choose Li-ion to get to Li-ion batteries. Search through the available item listings, or continue to refine the search further by using more detailed options in the left hand column. Entering specific keywords into the search bar at the top of any eBay page will also provide results.


The advantages that Li-ion batteries have over other rechargeable batteries, justify any faults they may have. They are highly recommended for people willing to spend a little more to see real benefits in the long run. When looking for a good purchase, remember not to focus so much on price, but rather consider what the battery will be used for, how much power can be held and for how long it can be used for.

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