It has been a couple of decades since the commercial debut of rechargeable lithium-ion batteries, and today they dominate the market as the top choice for portable power. G.N. Lewis pioneered work on these batteries as early as 1912 as a means of overcoming the inherent instability of highly reactive lithium metal. The lithium-ion battery boasts several advantages -- such as durability and eco-friendliness -- though it does have its share of disadvantages.
The lithium-ion battery's high energy density is perhaps its biggest edge over other rechargeables. By weight and by volume, it trumps the competition, storing as much as 150 watt-hours of energy in a single kilogram. Nickel-metal hydride (NiMH) battery packs, on the other hand, store only 60 to 70 watt-hours per kilogram, peaking at a comparatively low 100. Lead-acid batteries fare even worse, storing 25 watt-hours per kilogram -- a mere one-sixth of the lithium-ion battery's capacity. With respect to energy density, the lithium-ion battery is unquestionably the pound-for-pound champion.
Low Self-Discharge Rate
While a NiMH or a nickel-cadmium (NiCd) battery loses as much as 20 percent of its charge in a month, a lithium-ion battery loses around 5 percent, making it the perfect choice for travelers carrying electronic equipment. Prolonged storage, however, requires that the lithium-ion battery hold at least a 40 percent charge; storing a fully depleted battery cuts down on its overall life span significantly. Storage temperatures as low as -4 degrees Fahrenheit work best for extended periods, though newer lithium-ion battery packs function well after prolonged storage at room temperature.
The cost of the average lithium-ion battery often exceeds that of NiMH and NiCd batteries of the same capacity. For safe operation, manufacturers equip lithium-ion battery packs with a protection circuit, which limits the cell's voltage during charging and discharging to a specified safe range. The complexity involved in manufacturing this circuit translates to the added cost. However, in spite of the higher initial costs, the lithium-ion battery's power output over time makes it ultimately more economical than other rechargeable and disposable batteries. The life span of a typical lithium-ion battery extends to about two to three years.
Size- and Charger-Specific
There is currently no such thing as a universal lithium-ion battery; manufacturers design them to fit specific devices. Unlike NiMH and NiCd batteries, lithium-ion batteries do not come in standard cell sizes such as AA, C and D. Also, as a complete discharge or an overcharge damages or shortens the life of a lithium-ion battery, their chargers also come with sophisticated circuitry and are therefore more expensive.