Department of Chemical and Biomolecular Engineering, University of Maryland , College Park, Maryland 20742, United States.
Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University , Jinan 250100, P.R. China.
ACS Nano. 2017 May 23;11(5):4885-4891. doi: 10.1021/acsnano.7b01445. Epub 2017 May 4.
All-inorganic solid-state sodium-sulfur batteries (ASSBs) are promising technology for stationary energy storage due to their high safety, high energy, and abundant resources of both sodium and sulfur. However, current ASSB shows poor cycling and rate performances mainly due to the huge electrode/electrolyte interfacial resistance arising from the insufficient triple-phase contact among sulfur active material, ionic conductive solid electrolyte, and electronic conductive carbon. Herein, we report an innovative approach to address the interfacial problem using a NaPS-NaS-C (carbon) nanocomposite as the cathode for ASSBs. Highly ionic conductive NaPS contained in the nanocomposite can function as both solid electrolyte and active material (catholyte) after mixing with electronic conductive carbon, leading to an intrinsic superior electrode/electrolyte interfacial contact because only a two-phase contact is required for the charge transfer reaction. Introducing nanosized NaS into the nanocomposite cathode can effectively improve the capacity. The homogeneous distribution of nanosized NaS, NaPS, and carbon in the nanocomposite cathode could ensure a high mixed (ionic and electronic) conductivity and a sufficient interfacial contact. The NaPS-nanosized NaS-carbon nanocomposite cathode delivered a high initial discharge capacity of 869.2 mAh g at 50 mA g with great cycling and rate capabilities at 60 °C, representing the best performance of ASSBs reported to date and therefore constituting a significant step toward high-performance ASSBs for practical applications.
全固态钠硫电池（ASSB）由于其高安全性、高能量以及钠和硫资源丰富，是一种很有前途的固定储能技术。然而，目前的 ASSB 表现出较差的循环和倍率性能，主要是由于硫活性材料、离子导电固体电解质和电子导电碳之间的三相接触不足，导致电极/电解质界面电阻过大。在此，我们报告了一种使用 NaPS-NaS-C（碳）纳米复合材料作为 ASSB 正极来解决界面问题的创新方法。纳米复合材料中高离子导电性的 NaPS 在与电子导电碳混合后可同时充当固体电解质和活性材料（正极电解液），这导致电荷转移反应只需要两相接触，从而具有内在的优异电极/电解质界面接触。在正极中引入纳米尺寸的 NaS 可以有效提高容量。纳米复合材料正极中纳米尺寸的 NaS、NaPS 和碳的均匀分布可以确保高混合（离子和电子）电导率和足够的界面接触。NaPS-纳米 NaS-碳纳米复合材料正极在 60°C 时以 50 mA g 的电流密度下具有 869.2 mAh g 的初始高放电容量和出色的循环和倍率性能，代表了迄今为止报道的 ASSB 的最佳性能，因此朝着实用高性能 ASSB 迈出了重要一步。
