Stable lithium–sulfur full cells enabled by dual functional and interconnected mesocarbon arrays

Abstract

Lithium metal–sulfur (Li–S) batteries have gained wide attention due to extremely high energy density, but their application was hindered by the challenges related to both the sulfur cathode and Li anode. Herein, we designed dual functional, highly ordered, and interconnected mesoporous carbon (MPC) to address the challenges related to the cathode and anode simultaneously. On the anode, a thin layer of MPC annealed at 500 °C (MPC-500) was introduced to mechanically suppress Li dendrite growth, which provided interfacial protection on the Li metal and stabilized the Li plating/stripping. This novel anode showed excellent cycling stability at a high current density of 3 mA cm⁻². On the cathode, MPC annealed at 1300 °C (MPC-1300) was utilized to confine sulfur. The interconnected mesoporous carbon sphere with a large surface area significantly alleviated the shuttle effect, which contributes to the cycling stability of the Li–S battery. Meanwhile, the conductive carbon promotes electron transfer. When a Li–S full cell was assembled with MPC-500 and MPC-1300 as an anode interface layer and cathode additive, respectively, an exceptional reversible capacity of 607 mA h g⁻¹ was achieved at a discharge rate of 1 C (1675 mA g⁻¹) and maintained at a high capacity retention of 87.5% after 100 cycles.