The use of mixed carbon materials with improved oxygen transport in a lithium-air battery

Two commercial carbon blacks, Ketjen black EC600JD (KB600) and Super P with quite different porosity parameters, are used for the cathode of a lithium-air battery. With high specific pore volume, KB600 shows a higher weight specific capacity. However, Super P exhibits a super high volume specific capacity, about 7 times higher than that of KB600, ascribed to its higher proportion of pores with suitable size for the deposition of solid products. The effects of O-2 partial pressure and discharge rate on the specific capacity are investigated, combined with characterizations of contact angle and the structure of the electrodes. It is demonstrated that the Super P electrode possesses better O-2 transport that improves the use of the whole electrode volume, and the special mechanism of O-2 diffusion in the Super P electrode is proposed. By mixing KB600 with Super P with a weight ratio of 5:1, an electrode is obtained that exhibits increased O-2 transport. The weight specific capacity is 1219 mAh g(-1), about 1.2 times higher than that of KB600. (C) 2013 Elsevier B.V. All rights reserved