A combined electrolyte and separator for rechargeable lithium-ion batteries developed at Rice University in the US supplies energy at usable voltages and in high temperatures. An essential part of the non flammable, toothpaste-like composite is hexagonal boron nitride (h-BN), also known as ‘white graphene’.
The team, led by materials scientist Pulickel Ajayan, said batteries made with the composite functioned ‘perfectly’ in temperatures of 150°Cfor more than a month with negligible loss of efficiency. Test batteries operated consistently from room temperature to 150°C – one of the widest temperature ranges reported for such devices, the researchers said.
Researcher Marco-Túlio Rodrigues said: “We tested our composite against benchmark electrodes and found that the batteries were stable for more than 600 cycles of charge and discharge at high temperatures.”
Rodrigues added that batteries with the new electrolyte are more likely to be used in industrial and aerospace applications than in mobile phones. “[Oil and gas companies] put a lot of sensors around drill bits, which experience extreme temperatures,” he said. “It’s a real challenge to power these devices when they are thousands of feet downhole.”
Because h-BN is not a conductor and is not known to be an ionic conductor, the researchers didn’t expect it to assist battery performance. “But we thought a material that is chemically and mechanically resistant, even at very high temperatures, might give some stability to the electrolyte layer,” Rodrigues noted.
Lead researcher Ajayan concluded. “Pushing the boundaries of working temperature ranges is very interesting. There is no commercial battery product that works above about 80°C. Our interest is to break this barrier and create stable batteries at twice this temperature limit or more.”
Pic: Pic: Jeff Fitlow/Rice University
Author
Graham Pitcher
Source: www.newelectronics.co.uk