A positive-temperature-coefficient electrode with thermal cut-off mechanism for use in rechargeable lithium batteries

A novel positive-temperature-coefficient (PTC) electrode was prepared by coating a thin layer of epoxy-carbon PTC material in between the electroactive LiCoO2 layer and the electrode substrate and used for self-actuating thermal cut-off of Li-ion batteries when the batteries are overheated. Experimental results from cyclic voltammetry, impedance spectrometry and charge-discharge measurements demonstrate that the PTC electrode exhibits normal electrochemical behaviors at ambient temperature, but shows an enormous increase in the resistance at the temperature range of 100-130 degreesC. This PTC behavior of the electrode provides a current-limiting effect, acting as a reversible thermal shutdown switch for rechargeable lithium batteries. (C) 2004 Elsevier B.V. All rights reserved.