Symmetric Sodium-Ion Capacitor Based on Na0.44MnO2 Nanorods for Low-Cost and High-Performance Energy Storage

• Published in: ACS applied materials & interfaces Vol. 10; no. 14; pp. 11689 - 11698
• Main Authors: Chen, Zhongxue, Yuan, Tianci, Pu, Xiangjun, Yang, Hanxi, Ai, Xinping, Xia, Yongyao, Cao, Yuliang
• Format: Journal Article
• Language: English
• Published: American Chemical Society 11.04.2018
• Subjects: batteries; capacitance; cost effectiveness; electric power; electric vehicles; electrochemistry; energy; energy density; nanorods; sodium; Na0.44MnO2 nanorods; symmetric sodium-ion capacitor; energy storage; low cost; high performance
• DOI: 10.1021/acsami.8b00478
• ISSN: 1944-8244; 1944-8252

Batteries and electrochemical capacitors play very important roles in the portable electronic devices and electric vehicles and have shown promising potential for large-scale energy storage applications. However, batteries or capacitors alone cannot meet the energy and power density requirements because rechargeable batteries have a poor power property, whereas supercapacitors offer limited capacity. Here, a novel symmetric sodium-ion capacitor (NIC) is developed based on low-cost Na0.44MnO2 nanorods. The Na0.44MnO2 with unique nanoarchitectures and iso-oriented feature offers shortened diffusion path lengths for both electronic and Na+ transport and reduces the stress associated with Na+ insertion and extraction. Benefiting from these merits, the symmetric device achieves a high power density of 2432.7 W kg–1, an improved energy density of 27.9 Wh kg–1, and a capacitance retention of 85.2% over 5000 cycles. Particularly, the symmetric NIC based on Na0.44MnO2 permits repeatedly reverse-polarity characteristics, thus simplifying energy management system and greatly enhancing the safety under abuse condition. This cost-effective, high-safety, and high-performance symmetric NIC can balance the energy and power density between batteries and capacitors and serve as an electric power source for future low-maintenance large-scale energy storage systems.