Feng Lanxiang, Yu Peng, Fu Xuewei, Zhang Zheng-Min, Davey Kenneth, Wang Yu, Guo Zaiping, Yang Wei
College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, Sichuan, China.
State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu 610065, Sichuan, China.
ACS Nano. 2022 May 24;16(5):7982-7992. doi: 10.1021/acsnano.2c00882. Epub 2022 Apr 29.
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 exhibits a stable areal capacity of 6 mAh cm 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.
设计具有强多硫化物吸附能力的极性主体材料，以限制硫阴极中的穿梭效应。然而，一个关键问题是在循环过程中控制多硫化锂的扩散和沉积，这对循环稳定性和硫利用率有显著影响。在此，我们报告利用顺序吸附引导的自组装来设计两种具有相反多硫化物吸附梯度的核壳硫颗粒，以定量探索多硫化物扩散和沉积的调控。我们表明，硫颗粒的正核壳设计（PCSD@SP），即多硫化物吸附能力从主体内部到外部降低，在限制多硫化物扩散和调节多硫化物沉积方面比负核壳对应物（NCSD@SP）更有效。因此，硫负载量为7 mg cm的PCSD@SP电极在0.2C下130次循环中表现出6 mAh cm的稳定面积容量。在间歇充放电时，与NCSD@SP相比，PCSD@SP电极保持了优异的稳定性。我们得出结论，合理设计正核壳活性材料可用于调节多硫化物扩散和沉积，以促进电化学反应动力学和性能。所报道的研究结果将立即惠及一系列高性能锂硫电池设计领域的研究人员。
