Types of Batteries

Batteries can be divided into two types: primary or disposable batteries and secondary or rechargeable batteries.

Advantages of Batteries over Fuel Cells

The main advantages of batteries over fuel cells are their:

· Availability

· Portability

· Low cost

· Wide range of operating conditions

Disadvantages of Batteries When Compared to Fuel Cells

Batteries, however, have much shorter life spans and lack the power output of fuel cells. Power outputs of batteries are typically on the order of 100's of watts, whereas fuel cells can provide kilowatt to megawatt outputs, power enough to light a building or fuel a vehicle for hours. Under heavy energy demands, batteries can build up dangerous levels of heat and pressure, degrading the battery and possibly causing leaks of toxic compounds or even explosions. In addition, the limited life of primary batteries and the limited cycle life (number of times it can be recharged) of most secondary batteries necessitates the need for disposal of often dangerous and toxic battery materials.

Common Types of Primary and Secondary Batteries

Table 1 summarizes some of the common types of primary and secondary batteries.

Table 1. Some common types of Batteries.

	Battery Type	Anode	Cathode	Electrolyte	Advantages	Disadvantages
Primary Batteries	Alkaline Cell	Zn	MnO2	KOH	High energy density, long shelf life, good leak resistance, performs well under heavy or light use.	Costlier than zinc-carbon cell but more efficient
	Aluminum/Air Cell	Al	O2	KOH or neutral salt solution	Can operate exposed to sea water (neutral salt solution), easily replaceable electrolytes/electrodes	Anode quickly degrades, short shelf life, short operational life
	Leclanché Cell (Zinc Carbon or Dry Cell)	Zn	MnO2	NH4Cl or ZnCl2	Cheap and common (oldest available battery type)	Poor performance under heavy or continuous use.
	Lithium Cell	Li	Various liquid or solid materials	SOCl2, SO2Cl2, or organic solutions	Very high energy density, long shelf life, long operational life	Poor performance under heavy use, vulnerable to leaks or explosions
	Mercury Oxide Cell	Zn or Cd	HgO	KOH	Higher energy density than (Zn/MnO2) alkaline cell	High cost and being phased out due to toxicity concerns
	Zinc/Air Cell	Zn	O2	KOH	Environmentally benign, cheap, very high energy density, and virtually unlimited shelf life	Short operational life, low power density
Secondary (rechargeable) Batteries	Iron Nickel Cell	Fe	Ni(OH)2	KOH	Long life under a variety of conditions, excellent back-up battery	Low rate-performance, slow recharge rate
	Lead/Acid Cell	Pb	PbO2	dilute H2SO4(aq)	Low cost, long life cycle, operates well under a variety of conditions. Common car batteries	Minor risk of leakage
	Lithium Ion Cell	C, carbon compounds	Li2O, intercalated into graphite	LiPF6, LiBF4, related compounds	Relatively cheap, high energy density, long shelf life, long operational life, long cycle life	Minor risk of leakage
	Nickel/Cadmium Cell	Cd	Ni(OH)2	KOH	Good performance under heavy discharge and/or low temperature	High cost, can temporary loose cell capacity if not fully discharged before recharging (memory effect)
	Nickel/Metal Hydride (NiMH) Cell	Lanthanide or Ni alloys	Ni(OH)2	KOH	High capacity and power density	High cost, some memory effect
	Nickel/Zinc Cell	Zn	NiO	KOH	Low cost, low toxicity, good for high discharge rates	Zinc on the electrolyte tends to redeposit unevenly on anode, severely reducing efficiency
	Sodium/Sulfur Cell	Molten Na	Molten S	Al2O3	Inexpensive materials, long cycle life, high energy and power	High operational temperature lower efficiency, some danger of explosion upon degradation

Primary Components of a Battery

The primary component materials of a battery are the anode, cathode, electrolyte, and semi-permeable materials. In addition various catalysts have been used to enhance the performance of electrodes. For example, ruthenium(IV) oxide is used as a catalyst in a vanadium redox battery system. Table 1 summarizes some of the types of electrodes and electrolytes used in common batteries. Many advanced battery designs focus upon new materials for these key components.
Lithium Ion Batteries

Much of the recent battery work has focused on lithium-ion batteries, since they are the primary power source for the ever-growing field of small, rechargeable electronic devices. Nickel sulfide (Aldrich product 34,247-5), for example, was recently explored as a cathode material for rechargeable lithium batteries.2 Current research is also concerned with some very mundane materials in electrodes. New morphologies of graphite flakes, as a case in point, have been studied as anode material in lithium-ion batteries.3 Electrolytes are also very important in battery performance. An LiBF4 solution, for example in a butyrolacetone/ethylene carbonate solution has proven to be a highly conductive and highly thermally stable electrolyte for lithium-ion batteries.