3D interconnected crumpled porous carbon sheets modified with high-level nitrogen doping for high performance lithium sulfur batteries

Abstract

To enable the theoretically appealing Li–S electrochemistry in battery, the issues of the low conductivity and volume variation of the active materials as well as the intermediates diffusion need to be comprehensively addressed, which calls for rational structure design of multifunctional host material for sulfur. Herein, a novel strategy is proposed to construct 3D graphene-based N-doped porous carbon for Li–S batteries. In this strategy, interconnected macropore channels, abundant mesopores and highly accessible micropores are synergistically integrated into a conductive framework constructed by crumpled carbon sheets, and a high content of N-doping (∼18 at%) is simultaneously achieved. The obtained porous carbon possesses 3D conductive network, interconnected hierarchical porosities as well as large polarized specific surface, which endow the carbon matrix multifaceted structural merits for electrons/ions transfer, sulfur accommodation, and polysulfides immobilization. The obtained carbon sulfur composite exhibits a high reversible capacity of 1280 mA h g−1 at 0.2C, remarkable rate capabilities up to 3C and a prolonged cycling life over 500 cycles at 1C, showing intriguing promise for constructing high energy density Li–S batteries. This strategy provides a new perspective to porosity engineering and surface chemistry modification of carbon-based sulfur hosts and also other electrochemical electrode material.