Portable electronics such as notebooks, cell phones, and digital cameras have gained worldwide popularity resulting in higher demand for device mobility in our everyday lives. The need to have more power, longer life, and lighter solutions has led to the development of various battery chemistries such as lead-acid (SLA), nickel-cadmium (Ni-Cd), nickel-metal (Ni-MH), lithium-ion (Li-ion), and lithium-polymer (Li-polymer). These newly developed batteries have vastly improved the mobility and usage time of electronic devices through lighter-weight and the incorporation of higher energy densities.
There are numerous types of batteries that have different characteristics and applications. For portable electronic equipment, the primary end-user needs revolve around being lightweight and having both a high-energy density and long cycle life. The most common secondary batteries are Lead-acid batteries, Ni-Cd batteries, Ni-MH batteries and Lithium-Ion batteries. In addition to Alkaline batteries (primary batteries), secondary batteries (rechargeable batteries) have become a main stream solution for portable electronic products.
The following table displays a comparison of the main categories of secondary batteries:
|Nominal Voltage (V)||2||1.2||1.2||3.6 or 3.7||3.6|
|Positive electrode||PbO2||NiOOH||NiOOH||LiCoO2 or LiMn204||LiCoO2|
|Negative electrode||Pb||Cd||Hydrogen, storage alloy||Carbon||Carbon|
|Electrolyte||H2SO4||KOH||KOH||Organic solvent with LiPF6||Polymer gel|
|Charging Volt. Limit (V)||x||< 1.8||< 1.8||<= 4.2||<= 4.2|
|Cut-off discharging volt (V)||Depend on discharge rate||0.8 ~ 1.0||1||2.7 ~ 3.0||2.7 ~ 3.0|
|Capable of high discharge rate||1C *||10 C||2 ~ 3C||1 ~ 1.5C||1 ~ 1.5C|
|Capable of low discharge rate||Excellent||Excellent||Excellent||Excellent||Excellent|
|Self-discharge at 20 C (%/day)||0.1||1||1.5||0.3 ~ 0.6||0.3 ~ 0.6|
|Cycle life (Times)||200 ~ 400||200 ~ 500||> 500||> 500||> 500|
|Charging temp. range (C)||5 ~ 35||0 ~ 45||10 ~ 45||0 ~ 45||0 ~ 45|
|Discharging temp. range (C)||5 ~ 35||-10 ~ 60||-10 ~ 45||-10 ~ 60||-20 ~ 60|
|Environment Issue||Sulfuric acid solution may influence human health||Cadmium is a serious pollutant||Low pollutant||Low pollutant||Low pollutant|
|Package||Plastic case||Seal metal can||Seal metal can||Metal can Aluminum can||Aluminum laminate pack|
|Shape||Cube||Cylindrical||Cylindrical, Prismatic||Cylindrical, Prismatic||Prismatic|
|Price||Low||Low||More expensive than Ni-Cd||High||The highest|
|Consideration for electronic products||For low price products that require longer durability||Apply to products that requires higher discharge current and rapid charging||Apply to products that need greater battery capacity and easier charge/discharge||The same as Ni-MH, and especially for light weighted products||The same as Li-ion, and for products that require batteries of unique shape|
|Applications||Lightings system, UPS, toys||Power tools, cordless phone, camcorder, toys||Notebook, electronic razor, PDA, DVD player, cellular phone||Notebook, PDA, DVD player, digital camera, cellular phone||Notebook, PDA, cellular phone|
* C-rate: indicates the rate for the charge/discharge a battery. For instance, 0.2C mean it would require 0.2 times of nominal capacity to charge/discharge the battery.