Fresh water we can use for drinking or agriculture is only about 3 percent of the global water supply, and nearly 70 percent of that is trapped in glaciers and ice caps. So far, that was enough to keep us going, but severe draughts have left places like Jordan, Egypt, sub-Saharan Africa, Spain, and California with limited access to potable water.

One possible solution is to tap into the remaining 97 percent of the water we have on Earth. The problem is that this water is saline, and we need to get the salt out of it to make it drinkable. Desalination is also an energy-expensive process. But MIT researchers led by Jonathan Bessette might have found an answer to that. They built an efficient, self-regulating water desalination system that runs on solar power alone with no need for batteries or a connection to the grid.

Probing the groundwaters

Oceans are the most obvious source of water for desalination. But they are a good option only for a small portion of people who live in coastal areas. Most of the global population—more or less 60 percent—lives farther than 100 kilometers from the coast, which makes using desalinated ocean water infeasible. So, Bessette and his team focused on groundwater instead.

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If you're using a large battery for a specialized purpose—say grid-scale storage or an electric vehicle—then it's possible to tweak the battery chemistry, provide a little bit of excess capacity, and carefully manage its charging and discharging so that it enjoys a long life span. But for consumer electronics, the batteries are smaller, the need for light weight dictates the chemistry, and the demand for quick charging can be higher. So most batteries in our gadgets start to see serious degradation after just a couple of years of use.

A big contributor to that is an internal fragmentation of the electrode materials. This leaves some of the electrode material disconnected from the battery's charge handling system, essentially stranding the material inside the battery and trapping some of the lithium uselessly. Now, researchers have found that, for at least one battery chemistry, it's possible to partially reverse some of this decay, boosting the remaining capacity of the battery by up to 30 percent.

The only problem is that not many batteries use the specific chemistry tested here. But it does show how understanding what's going on inside batteries can provide us with ways to extend their lifespan.

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