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Polar host materials with strong adsorption capacity of polysulfides are designed to limit the shuttle effect in sulfur cathodes. However, a critical problem is to control diffusion and deposition of lithium polysulfides during cycling, which significantly impacts cycling stability and sulfur utilization. Here, we report using a sequential adsorption-guided self-assembly to design two types of core-shell sulfur particles with opposite polysulfide adsorption gradients to explore quantitatively the regulation of polysulfide diffusion and deposition. We show that a positive core-shell design of sulfur particles (PCSD@SP), i.e., polysulfide adsorption capability decreasing from the interior to the exterior of the host, is more effective in restricting polysulfide diffusion and regulating polysulfide deposition than the negative core-shell counterpart (NCSD@SP). As a result, the PCSD@SP electrode with a sulfur loading of 7 mg cm -2 exhibits a stable areal capacity of 6 mAh cm -2 over 130 cycles at 0.2C. At intermittent discharge/charge, the PCSD@SP electrode retains excellent stability compared with the NCSD@SP. We conclude that rational design of positive core-shell active materials can be used to regulate polysulfide diffusion and deposition to boost electrochemical reaction dynamics and performance. The reported findings will be of immediate benefit to a range of researchers in the design of high-performance lithium-sulfur batteries.

Fast recovery in a nonaqueous environment is a big challenge for hydrogel actuators. In this work, a temperature-responsive hydrogel actuator with outstandingly rapid recovery in air was reported. The hydrogel with bionic large-ranged gradient structure was fabricated by copolymerization of hydrophilic monomer hydroxyethyl acrylate (HEA) and N-isopropylacrylamide in the dispersion of Laponite utilizing a facile electrophoretic method. The deformation degree and time can be regulated by varying the concentration of HEA to change the lower critical solution temperature (LCST) and swelling of the hydrogel. A dynamic equilibrium between the water into and out of the hydrogel was observed, and the hydrogel showed no shrink above LCST. The synthesized hydrogels showed fast response in hot water and rapid recovery in air. Such nonshrink characteristics and excellent reversibility made it possible for these hydrogels to be used as temperature-controlled microfluidic switches. This work provided an approach to design fast recovery hydrogel actuators by the incorporation of hydrophilic monomers and extend the application of the hydrogel actuators into fields such as soft robots, micromanipulation, microfluidics and artificial muscles in various environments.