Lithium-sulfur batteries with superior cycle stability by employing porous current collectors

Conventional lithium-sulfur (Li-S) batteries suffer from severe capacity fade and self-discharge attributed to sulfur dissolution and polysulfide diffusion. Here we present a porous cathode architecture which suppresses the loss of active material and self-discharge behavior in Li-S systems. 3D sulfur-nickel foam cathodes (SNF cathodes) have porous, electrically conductive Ni foam substrates as bifunctional current collectors. It was found that these cathodes have a stable cycle life with a high discharge capacity retention rate of 92% after 50 cycles. Moreover, the SNF cathodes reduce the self-discharge and retain 85% of their original capacities after resting for two months. The porous architecture of Ni foam accommodates the active material and traps polysulfides in the cathode region during cycling and battery storage, effectively reducing the loss of active material and capacity. In addition, it provides an excellent internal electron transport network by ensuring intimate contact between the active material and Ni foam, resulting in low internal impedance and improved capacities. The study demonstrates that the 3D Ni foam is an attractive bifunctional current collector for Li-S batteries. (C) 2013 Elsevier Ltd. All rights reserved.