PEI/Super P Cathode Coating: A Pathway to Superior Lithium–Sulfur Battery Performance

Abstract

Lithium–sulfur batteries exhibit a high energy density of 2500–2600 Wh/kg with affordability and environmental advantages, positioning them as a promising next-generation energy source. However, the insulating nature of sulfur/Li2S and the rapid capacity fading due to the shuttle effect have hindered their commercialization. In this study, we propose a method to boost the performance of lithium–sulfur batteries by modifying the sulfur cathode with a coating layer composed of polyethyleneimine (PEI) and Super P conductive carbon. The PEI/Super P-modified electrode retained 73% of its discharge capacity after 300 cycles at the 2 C scan rate. The PEI/Super P coated layer effectively adsorbs lithium polysulfides, suppressing the shuttle effect and acting as an auxiliary electrode to facilitate the electrochemical reactions of sulfur/Li2S. We analyzed the PEI/Super P-modified electrodes using symmetric cells, electrochemical impedance spectroscopy, and cyclic voltammetry. The battery manufacturing method presented here is not only cost-effective but also industrially viable due to its compatibility with the roll-to-roll process.