In situ synthesis of flexible elastic N-doped carbon foam as a carbon current collector and interlayer for high-performance lithium sulfur batteries

Abstract

A flexible elastic N-doped carbon foam (NCF) has been successfully synthesized in situ via direct carbonization/pyrolysis of polyurethane foam, which is a facile, cost-effective and environmentally friendly method. Due to its uniform three-dimensional connected structure, its reasonable composition with N doping and its high electronic conductivity, the NCF can function as both a three-dimensional current collector and a carbon interlayer for lithium sulfur batteries. As a typical model, cathodes consisting of NCF and CNT/S were prepared. The resulting batteries deliver a large reversible capacity of 1124 mA h g⁻¹ at 0.5C and retain a high specific capacity of 902.8 mA h g⁻¹ after 100 cycles, with a coulombic efficiency of 98.6% throughout the cycles. Furthermore, a discharge capacity of 691.8 mA h g⁻¹ is still attainable when the rate is increased to 2.0C. The excellent cycling performance and rate capability are contributed to the uniform flexible elastic, conductive 3D framework and good porosity, and may have great significance for large-scale commercial applications of Li–S batteries.