Monday, 12 June 2017

Future Car - Electricity & Battery Technology

Rechargeable Battery

Even though a rechargeable battery also uses chemicals it does so in a different way. The chemistry is used primarily to move electrons from one place in the battery to another. The chemicals do eventually wear out, but at a far slower rate than a standard electrochemical battery. When a rechargeable battery is put to use electron flow moves from one part of the battery to another. When the battery is recharged that electron flow is reversed. Common rechargeable batteries include;

Lead-Acid batteries (common car battery)

Nickle Cadmium (NiCad)

Nickle Metal Hydride (NiMH)

Lithium Ion (Li-ion)

Lead-Acid Battery: The first rechargeable battery was invented by Frenchman Gaston Plante in 1859. This is the lead-acid battery so commonly found in gasoline or diesel engined cars. The battery consists of alternating plates of lead and lead dioxide. Between these plates is a solution of sulfuric acid. As the battery is used (dischar ged) the lead on the lead-plate combines with the sulfur to create lead sulfate. This process also frees up an electron. Then the lead dioxide, some hydrogen ions, sulfate ions, plus electrons from the lead plate, work together to create lead-sulfate and water on the lead dioxide plate.This reaction is completely reversible by applying more voltage to the battery than it produces. The excess voltage (about 13.4 volts) breaks up the lead-sulfate, combines the sulfate with water (producing sulfuric acid) and rebinds the previously free electrons back to the lead plate.

These lead-acid batteries last a considerable amount of time, have no "memory", and though heavy are quite reliable. They are also quite cheap (despite what you pay for them) to produce.

Nickel Cadmium Battery: These batteries are similar to the lead-acid type except that electrodes are nickel-hydroxide (instead of lead-dioxide) and cadmium (instead of lead), with potassium-hydroxide (instead of sulfuric-a cid) as the electrolyte. NiCad batteries suffer from a "memory effect" in that if the battery is discharged to a certain level then fully recharged after x number of recharges the battery will stop discharging once it reaches that point again. e.g. if the battery is routinely discharged to 50% of capacity it will stop producing current when it reaches that capacity again after a recharge. On the upside NiCad batteries lose little energy to the air, do well in the cold, and can take a trickle charge.

Nickel Metal Hydride:This battery is similar to the Nick el Cadmium except that it uses a hydrogen absorbing alloy of metals (this alloy is a metal hydride; good at storing hydrogen) instead of cadmium at the negative electrode. NiMH batteries have two to three times the storage capacity of NiCad batteries. They have a long shelf-life, wide operating temperature range, and like NiCad do not "leak" a great deal of energy to the air. A.K.A. self-discharge.

Lithium-Ion: The lithium ion battery has the three same basic internal structures; a cathode, anode, and electrolyte. In the case of the Li-ion battery the cathode is either lithium cobalt oxide, lithium iron phosphate, or lithium manganese oxide. The anode is typically graphite or a lithium graphite alloy. When Li-ion cells are discharging, the lithium is extracted from the anode and inserted onto the cathode. When the Li-ion cell is charging the lithium-ions reverse flow; depositing ions onto anode from the cathode. The electrolyte is typically a lithium salt.

Lithium-ion Electrician Service College Station batteries, unlike NiCads, do not suffer from a "memory" effect, do not self-discharge readily (only about 5% per month), and can be charged and discharged hundreds of times.

Energy Density: Energy density is the amount of energy storage per kiogram of weight. By this measure the following battery types store; (source for table below

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