Electrode could lead to large-capacity rechargeable battery

Stanford researchers claim their latest technology could be used to develop an efficient, durable, high-power rechargeable battery to store large quantities of excess power.

They are reported to have created an electrode that employs crystalline nanoparticles of a copper compound in order to achieve this.

In laboratory tests, the electrode is reported to have survived 40,000 cycles of charging and discharging, after which it could still be charged to more than 80 per cent of its original charge capacity. The average lithium-ion battery can only handle about 400 charge/discharge cycles before it deteriorates too much to be of practical use.

‘At a rate of several cycles per day, this electrode would have a good 30 years of useful life on the electrical grid,’ said Colin Wessells, a graduate student in materials science and engineering who is the lead author of a paper describing the research, published this week in Nature Communications.

The electrode’s durability is reportedly derived from the atomic structure of the crystalline copper used to make it. The crystals have an open framework that allows ions — electrically charged particles whose movements en masse either charge or discharge a battery — to easily go in and out without damaging the electrode.

Most batteries fail because of accumulated damage to an electrode’s crystal structure.

The ions can move freely, so the electrode’s cycle of charging and discharging is extremely fast, which is important because the power derived from a battery is proportional to how fast the electrode can be discharged.

To maximise the benefit of the open structure, the researchers needed to use the correct-size ions, which turned out to be hydrated potassium.

‘It fits perfectly,’ said Yi Cui, co-author of the paper. ‘Potassium will just zoom in and zoom out, so you can have an extremely high-power battery.’

The speed of discharging the electrode is further enhanced because the particles of electrode material that Wessells synthesised were a mere 100 atoms across — tiny, even by nanoparticle standards.

Wessells has been able to readily synthesise the electrode material in gram quantities in the lab. He said the process should easily be scaled up to commercial levels of production.

‘We put chemicals in a flask and you get this electrode material. You can do that on any scale,’ he said. ‘There are no technical challenges to producing this on a big enough scale to actually build a real battery.’