Although mostly unnoticed, batteries have made significant progress over the last 20 years. We don’t perceive this because our use of electronics has increased much more and hence we keep feeling a shortage of battery capacity (electronics has also become much more energy savvy, but at the same time the number of transistors we use has skyrocket eating up all the savings in energy requirement per transistor).
The density of energy storage has increased significantly with lithium-ions batteries, the ones we have in our smartphones, with some undesired results as it became evident with the recent “explosion” of a few Samsung Galaxy Note 7 (a very insignificant percentage but more than enough to make headlines and force Samsung to stop production).
High energy density in “wearable” devices is a must since we want to keep their dimension to a minimum and pack lot of energy to support their intense use. However, in other kind of application this density requirement is not as stringent.
Here comes the result obtained at the University of Waterloo where chemists have managed to create a zinc-ion based battery costing half of an equivalent lithium-ion battery although requiring a bigger space (because of lower energy density).
Even more interesting is the use of water based electrolyte as a medium to transport electrons, rather than the flammable organic electrolyte needed in a lithium-ion battery. Also, the manufacturing process is cheaper since it does not require special precaution to ensure a dry production environment and care to manage flammable substances.
The challenge chemists had to overcome is that Zinc is ok for the negative electrode (because of its potential high energy density) but it has problem compatibility with positive electrode. They solved this by creating a positive electrode made with vanadium oxide bronze pillared by Zn2+ ions.
The resulting battery lends itself to application for storing power in a grid, like storing power created by residential photovoltaic systems whilst application in wearable devices or as car accumulator are not suitable.