At last, a phone battery that lasts longer – much longer

A new type of battery that carries twice the energy of today's lithium-ion ones could arrive in smartphones as early as next year.

The "lithium metal" technology is an engineering breakthrough that allows a battery to hold twice as many ions - the particles that store a battery's charge - as lithium-ion products.

It could mean manufacturers being able to shrink the batteries inside phones and maintain their capacity, or use batteries of the same size that can keep a phone running for twice as long.

Smartphone and laptop manufacturers have long sought to extend their products' battery life but have been frustrated by the chemical limits of lithium-ion technology, which has improved only marginally in recent years even as microchips get exponentially more powerful.

The new batteries have been developed by SolidEnergy Systems, a company started at the Massachusetts Institute of Technology, which plans to make them available to smartphone and wearable manufacturers next year and electric car makers the year after.

In typical lithium-ion batteries, ions move from a negatively-charged graphite cathode to a positively-charged anode through a solution known as an electrolyte, sending electrons that were attached to the ions through a circuit that powers a device such as a phone.

While graphite has proved the best and most reliable substance for a cathode to date, it can only hold so many ions. Researchers have long aimed to replace this with a lithium-metal foil, which can hold more ions, but the foil has typically reacted badly with the electrolyte, causing it to overheat, potentially igniting and rapidly losing capacity.

SolidEnergy Systems has developed a hybrid electrolyte solution which does not react badly with the lithium-metal foil, making it as safe and reliable as an everyday battery.

''It is kind of the holy grail for batteries,'' Qichao Hu, SolidEnergy's chief executive, told MIT News.

''With two-times the energy density, we can make a battery half the size, but that still lasts the same amount of time, as a lithium ion battery. Or we can make a battery the same size as a lithium ion battery, but now it will last twice as long.''

As well as vastly increasing phone life, allowing two days or more of charge, the new battery could double the range of electric cars, reducing the ''range anxiety'' that has afflicted many electric car drivers.

Several other purported replacements for lithium-ion have been touted, but Hu said the lithium-metal technology would fit with current manufacturing processes.