Batteries based on water are one step closer to being commercially viable, thanks to a new design that drastically extends their lifespan. The first application could be in powering e-scooters, say researchers.
Lithium-ion batteries, which are currently used in everything from smartphones to electric cars, offer many benefits such as a high energy density, but can also explode or catch fire when they fail because they use dangerous organic solvents as an electrolyte in combination with a lithium anode.
As such, teams around the world are working to develop replacement technologies. 鈥淥ur strategy is to replace the organic electrolytes currently used in lithium-ion batteries with a water electrolyte,鈥� says at RMIT University in Melbourne, Australia.
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It isn鈥檛 possible to simply put water in a lithium-ion battery because water and lithium are highly explosive in combination. Instead, the team鈥檚 batteries use a mix of water and inorganic salts as an electrolyte and zinc as the anode.
However, a major issue with water batteries has been the growth of spiky metallic structures, called dendrites, on the zinc anodes. These dramatically reduce battery life and lead to short circuits and other technical problems.
To address this, the team has developed a new process in which the anode and cathode of the battery are coated in a metal compound called bismuth oxide. Previous water batteries would lose half of their capacity after 500 charging cycles, but Ma says the new ones only lose 15 per cent in that time.
Still, the batteries aren鈥檛 quite ready to power a car, he says, with even their best prototypes having only 30 per cent of the energy density of a battery used in Tesla electric vehicles. But Ma says he is almost certain that, given the pace of progress with water batteries in recent years, they will eventually reach parity with lithium-ion versions.
In fact, he believes their latest water batteries could be used on e-scooters today, as these devices don鈥檛 need huge amounts of power.
at the University of Adelaide, Australia, says he is impressed with the durability of the zinc anodes in the research. 鈥淎chieving this level of performance is truly remarkable,鈥� he says.
Advanced Materials
