Electric vehicle
Electric Vehicle Technology Explained, Second EditionTable 3.6
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| 52 Electric Vehicle Technology Explained, Second Edition Table 3.6 Nominal properties of lithium ion batteries Specific energy Wh kg −1 Energy density Wh l −1 Specific power W kg −1 Nominal cell voltage V Amphour efficiency Very good Internal resistance Very low Commercially available Larger LIBs have become the standard battery for electric road vehicles Operating temperature Ambient Self-discharge Very low per month Number of life cycles >1000 Recharge time h, but can be charged to 80% of their capacity in under 1 h about three times that of lead acid batteries, and this could give a car a very reasonable range. However, large batteries have until recently been prohibitively expensive, though the price has now dropped to the point where the LIB is the preferred battery for EVs. With recent developments and improved specific energies large companies have setup production lines. As with most components a ready market combined with quantity production often leads to rapid development and further price reductions. Most modern EVs including the Nissan Leaf, the Mitsubishi MiEV, the Tesla Roadster and the Chevrolet Volt use LIBs. The battery in the Leaf has a capacity of 24 kWh and the specific energy of the cells is 140 Wh kg. The predicted development of the battery by 2015 will give a specific energy of 200 Wh kg −1 3.7 Metal–Air Batteries 3.7.1 Introduction The metal–air batteries represent an entirely different development, in the sense that the batteries cannot be recharged simply by reversing the current. Instead the spent metal electrodes must be replaced or reprocessed. The metal electrodes can thus be considered as a kind of fuel. The spent fuel is then sent to a reprocessing plant where it will be turned into new fuel. The battery electrolyte will also normally need to be replaced. This is not a dissimilar concept to conventional IC engine vehicles where they stop periodically to refuel, with the added advantage that the vehicle will have the main attributes of an EV – quietness and zero emissions. As such it may appeal to motorists who are used to refuelling their vehicles and maybe slow to adapt to change. 3.7.2 The Aluminium–Air Battery The basic chemical reaction of the aluminium–air battery is essentially simple. Aluminium is combined with oxygen from the air and water to form aluminium hydroxide, |