Unlocking Enhanced Capacitive Deionization of NaTi2(PO4)3/Carbon Materials by the Yolk-Shell Design

作者：Liu, Xiaohong; Xu, Xingtao^*; Xuan, Xiaoxu; Xia, Wei; Feng, Guilin; Zhang, Shuaihua; Wu, Zhen-Guo; Zhong, Benhe; Guo, Xiaodong; Xie, Keyu; Yamauchi, Yusuke^*

来源：Journal of the American Chemical Society, 2023.

DOI：10.1021/jacs.3c01755

• METAL-ORGANIC-FRAMEWORKS
• PERFORMANCE
• CARBON
• GRAPHENE
• NANOCRYSTALS
• ELECTROLYTE
• SUPERIOR
• SPHERES

The low salt adsorption capacities (SACs) of benchmark carbon materials (usually below 20 mg g-1) are one of the most challenging issues limiting further commercial development of capacitive deionization (CDI), an energetically favorable method for sustainable water desalination. Sodium superionic conductor (NASICON)-structured NaTi2(PO4)3 (NTP) materials, especially used in combination with carbon to prepare NTP/C materials, provide emerging options for higher CDI performance but face the problems of poor cycling stability and dissolution of active materials. In this study, we report the development of the yolk- shell nanoarchitecture of NASICON-structured NTP/C materials (denoted as ys-NTP@C) using a metal-organic framework@ covalent organic polymer (MOF@COP) as a sacrificial template and space-confined nanoreactor. As expected, ys-NTP@C exhibits good CDI performance, including exemplary SACs with a maximum SAC of 124.72 mg g-1 at 1.8 V in the constant-voltage mode and 202.76 mg g-1 at 100 mA g-1 in the constant-current mode, and good cycling stability without obvious performance degradation or energy consumption increase over 100 cycles. Furthermore, X-ray diffraction used to study CDI cycling clearly exhibits the good structural stability of ys-NTP@C during repeated ion intercalation/deintercalation processes, and the finite element simulation shows why yolk-shell nanostructures exhibit better performance than other materials. This study provides a new synthetic paradigm for preparing yolk-shell structured materials from MOF@COP and highlights the potential use of yolk-shell nanoarchitectures for electrochemical desalination.

• 单位
  西北工业大学; 山东大学; y; 四川大学