Supercharged lithium batteries

Rechargeable lithium batteries for portable electronic devices, such as laptop computers and cellular phones, require electrodes that can conduct both electrons and ions. Today, most rechargeable batteries use lithium metal oxides, such as LiCoO₂, as the positive electrode. But despite its popularity, LiCoO₂ is a fairly expensive material so scientists are always on the lookout for cheaper alternatives. Researchers at MIT led by Yet-Ming Chiang report a surprising candidate in the October issue of Nature Materials.

Back in 1997, scientists discovered that lithium iron phosphate (LiFePO₄) can be used as a high-voltage electrode for lithium batteries. The material is cheap, environmentally friendly and non-toxic, yet commercial success was stymied by its extremely poor electronic conductivity. Chiang and colleagues now show that doping LiFePO₄ with a small amount of another metal ion, such as Nb⁵⁺, can boost its electronic conductivity by an astonishing eight orders of magnitude—some 10 million times better than before.

Electronically conductive phospho-olivines as lithium storage electrodes pp123-128

Sung-yoon Chung, Jason T. Bloking and Yet-ming Chiang

Published online: 22 September 2002 | doi 10.1038/nmat732

Abstract | Full text