Battery Chemistry

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
Protection Module Nil Nil Nil Yes Yes
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
Trickle Charging Yes Yes No No No
Memory effect No Yes No No No
Charging method CC-CV CC CC CC-CV CC-CV
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.