Constructing mesoporous hollow polysulfane spheres bonded with short-chain sulfurs (Sx, x≤3) as high-performance sulfur cathodes in both ether and ester electrolytes

Although organic polysulfanes are promising cathodes for high-performance lithium-sulfur batteries because of the covalently bonded sulfur to suppress the shuttle effect, those with linear polymer substrates tend to generate long-chain sulfurs (S-x, x = 4-16) that is liable to yield soluble lithium polysulfides and thus could not effectively prevent the shuttle effect. Herein, novel mesoporous hollow sulfurized aminophenol-formaldehyde resin (polysulfane)/carbon nanotube (SAC) spheres with covalently linked short-chain sulfurs (S-x, x <= 3) are synthesized using a self-template polymerization reaction followed by dissolution and vulcanization processes. The three-dimensional network of aminophenol-formaldehyde resin, the mesoporous hollow structure, and the vulcanization temperature benefit the formation of the short-chain sulfurs (S-x, x <= 3), suppressing the shuttle effect efficiently. The ex-situ analyses confirm that the unlithiated part of C-S bond could boost the electrochemical kinetics of delithiated reaction. Therefore, the as-prepared SAC cathode exhibits excellent rate performances and high reversible capacities at varied densities, even obtaining a superior structure stability and a very stable cyclability with a loss as low as 0.022% per cycle within 1000 cycles at 2 C. Moreover, the SAC could perform stably both in ester and the ether electrolytes.