How a lithium-ion battery works
A. It is conventional with lithium batteries to refer to the negative electrode as the anode, and the positive electrode as the cathode. The two electrodes, with an electrically insulating separator between them, are often rolled up like a Swiss roll.
B. During discharge, electrical current flows from the anode to the cathode through the device the battery is powering (symbolised here by a light bulb). Simultaneously, positively charged lithium ions travel from the anode to the cathode through the separator.
C. On reaching the cathode, the lithium ions embed themselves in its metal oxide structure, which simultaneously accepts electrons from the external circuit.
D. The anode is typically made of carbon, the cathode is typically made of a cobalt or manganese oxide. The electrolyte (the liquid surrounding the electrodes) is usually composed of lithium salts in an organic solvent, such as ether.
E. During charging the process occurs in reverse. That matters, because the less energy the battery can store, the more limited the car's range. The limited range of electric cars is one of the main reasons people are unwilling to switch to them. But the good news is there is scope for improvement. Professor Brandon reckons we could see a five-fold increase in energy density over the next two decades, perhaps even 10-fold or more, if new technologies prove successful. A lot of current research is focused on "lithium-air" batteries, where much of the battery would be replaced with oxygen drawn from the atmosphere. Even so, says Professor Brandon, the limits of lithium battery chemistry mean they will never come near gasoline in terms of energy density. Indeed, in most handheld gadgets improvements in running time have had less to do with the performance of batteries than with the great steps that have been made reducing power consumption. The same is likely to be true for electric vehicles for the foreseeable future - engineers will have to design them around the limitations of batteries.
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B. During discharge, electrical current flows from the anode to the cathode through the device the battery is powering (symbolised here by a light bulb). Simultaneously, positively charged lithium ions travel from the anode to the cathode through the separator.
C. On reaching the cathode, the lithium ions embed themselves in its metal oxide structure, which simultaneously accepts electrons from the external circuit.
D. The anode is typically made of carbon, the cathode is typically made of a cobalt or manganese oxide. The electrolyte (the liquid surrounding the electrodes) is usually composed of lithium salts in an organic solvent, such as ether.
E. During charging the process occurs in reverse. That matters, because the less energy the battery can store, the more limited the car's range. The limited range of electric cars is one of the main reasons people are unwilling to switch to them. But the good news is there is scope for improvement. Professor Brandon reckons we could see a five-fold increase in energy density over the next two decades, perhaps even 10-fold or more, if new technologies prove successful. A lot of current research is focused on "lithium-air" batteries, where much of the battery would be replaced with oxygen drawn from the atmosphere. Even so, says Professor Brandon, the limits of lithium battery chemistry mean they will never come near gasoline in terms of energy density. Indeed, in most handheld gadgets improvements in running time have had less to do with the performance of batteries than with the great steps that have been made reducing power consumption. The same is likely to be true for electric vehicles for the foreseeable future - engineers will have to design them around the limitations of batteries.
Follow @LaNUBlog & @Hon_KingSIMEO on Twitter for Updates
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