Polyethyleneimine inducing the N-doped porous carbon skeleton to boost Na3V2(PO4)3 with excellent sodium storage and thermal safety properties

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-10, Vol.498, p.155536, Article 155536
• Main Authors: Qian, Chenghao, Wang, Shengsi, Liu, Changcheng, Huang, Que, Zhang, Baofeng, Chen, Yanjun
• Format: Article
• Language: English
• Subjects: N-doped porous carbon framework; Na3V2(PO4)3; Polyethyleneimine; Sodium ion batteries; Thermal safety properties
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.155536

[Display omitted] •N-doped porous carbon skeleton from PEI is utilized to modify NVP.•This carbon substrate possesses larger surface, relieves stress-strain and allows accelerated electronic transportation.•3wt.%PEI reveals excellent electrochemical performance in both half and full cells.•Thermodynamic and kinetic properties are analysed using accelerated rate calorimetry in half and full cells.•In-situ EIS testing is conducted to explore the kinetic characteristics during charge/discharge process. The poor intrinsic electron/ion conductivity of Na3V2(PO4)3 (NVP) makes it challenging to achieve satisfactory electrochemical performance. Herein, in-situ construction of N-doped porous carbon framework derived from polyethyleneimine (PEI) is employed to modify NVP system. PEI is a highly branched polymer containing abundant carboxyl and amine groups, and the free electrons of nitrogen atoms facilitate the formation of stable complexes with metal ions, thereby enhancing the cyclic stability of NVP. Meanwhile, the N-doped porous carbon framework possesses larger surface area to supply more active sites. The unique porous construction can relieve the stress–strain to enhance the structural stability. Besides, N-doped carbon substrate allows accelerated electronic transportation to improve the kinetics of NVP. Accordingly, Na3V2(PO4)3/C@3wt.%PEI (3wt.%PEI) exhibits an impressive specific capacity of 116.6 mAh g−1 at 0.1 C. Furthermore, after 1000 cycles at a current density of 20 C, it maintains a capacity of 74.6 mAh g−1, with an impressively low capacity decay rate of 0.0822 %. Moreover, the initial discharge specific capacity of the CHC//3wt.%PEI full cell is 266.02 mAh g−1, with an average voltage of 1.95 V and an energy density of 439.78 Wh kg−1. In-situ electrochemical impedance spectroscopy testing is conducted to explore the kinetic characteristics during the charge and discharge process. Additionally, the thermodynamic and kinetic properties are quantitatively compared using the accelerated rate calorimetry in both half-cell and full-cell configurations.