Self-Supported NaTi2(PO4)3 Nanorod Arrays: Balancing Na+ and Electron Kinetics via Optimized Carbon Coating for High-Power Sodium-Ion Capacitor

Ming Chen; Qinnan Zhou; Asma Iqbal; Xuejiao Liu; Ali Nazakat; Changyu Yan; Heng Tian; Wenqian Li; Yuchi Zhang; Boxu Dong; Jiantao Zai; Xuefeng Qian

doi:10.1021/acsami.0c13766

Self-Supported NaTi₂(PO₄)₃ Nanorod Arrays: Balancing Na⁺ and Electron Kinetics via Optimized Carbon Coating for High-Power Sodium-Ion Capacitor

ACS Appl Mater Interfaces. 2020 Nov 11;12(45):50388-50396. doi: 10.1021/acsami.0c13766. Epub 2020 Oct 27.

Authors

Affiliation

¹ Shanghai Electrochemical Energy Devices Research Center, School of Chemistry and Chemical Engineering and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, P. R. China.

PMID: 33108718
DOI: 10.1021/acsami.0c13766

Abstract

The NaTi₂(PO₄)₃ (NTP) anode materials exhibit high Na⁺ diffusion dynamics; carbon-based materials can effectively improve its limited electronic conductivity. However, the low Na⁺ diffusion of NTP/C composite materials from inhomogeneous carbon mixing or uncontrollable carbon coating cannot keep up with fast electron transfer, leading to undesirable electrochemical performances. Herein, a uniform and controllable carbon layer is designed on the self-supported-coated NTP nanorod arrays with binder-free (NTP@C NR) to improve Na⁺ and electron kinetics simultaneously. As a result, the NTP@C NR electrodes possess initial coulombic efficiency (ICE = 97%), good rate capabilities (89.1 mA h g^-1 at 100 C), and stability with ≈78.4% of capacity retention rate at even 30 C over 1200 cycles. The sodium-ion capacitors with NTP@C NR as an anode and commercially activated carbon as a cathode exhibit ∼9180.0 W kg^-1 of power density at 10 A g^-1 and super high retention of ≈94.5% at 1 A g^-1 over 7000 cycles. This work will help balance transport kinetics between the ion and electron for materials applied in storage devices.

Keywords: controllable carbon coating; self-supported NaTi2(PO4)3 nanorod arrays; sodium-ion capacitors; stable surface; ultrafast transport kinetics.