Junqin Li

Electrospun N-Doped Hierarchical Porous Carbon Nanofiber with Improved Degree of Graphitization for High-Performance Lithium Ion Capacitor

The lithium-ion capacitor (LIC) has been regarded as a promising device that combines the merits of lithium-ion batteries and supercapacitors, and that meets the requirements for both high energy and high power density. The development of advanced electrode materials is the key requirement. Herein, we report the bottom-up synthesis of activated carbon nanofiber (a-PANF) with a hierarchical porous structure and a high degree of graphitization. Electrospinning has been employed to prepare an interconnected fiber network with macropores, and ferric acetylacetonate has been introduced as both a mesopore-creating agent and a graphitic catalyst to increase the degree of graphitization. Furthermore, chemical activation enlarges the specific surface area by producing abundant micropores. Half-cell evaluation of the as-prepared a-PANF gave a discharge capacity of 80u2005mAu2009hu2009g-1 at 0.1u2005Au2009g-1 within 2-4.5u2005V and no capacity fading after 1000 cycles at 2u2005Au2009g-1 , which represents a significant improvement compared to conventional activated carbon (AC). Furthermore, an as-assembled LIC with a-PANF cathode and Fe3 O4 anode showed a superior energy density of 124.6u2005Wu2009hu2009kg-1 at a specific power of 93.8u2005Wu2009kg-1 , which remained at 103.7u2005Wu2009hu2009kg-1 at 4687.5u2005Wu2009kg-1 . This indicates promising application potential of a-PANF as an electrode material for efficient energy storage systems.

NaCl-templated synthesis of hierarchical porous carbon with extremely large specific surface area and improved graphitization degree for high energy density lithium ion capacitors

Li ion capacitors (LICs) are emerging as a promising device to integrate the high power density of supercapacitors with the high energy density of Li ion batteries. However, the insufficient specific capacity of the conventional capacitive electrode presents a great challenge in achieving high energy density for LICs. Herein, we demonstrate the synthesis of hierarchical porous carbon with an extremely large specific surface area of 3898 m2 g−1 and an improved graphitization degree by using egg white biomass as a precursor and NaCl as a template, in which dual functional NaCl served both as a macropore creating template and a graphitic catalyst to enhance the graphitization degree. With rational design, the developed porous carbon exhibits a noticeably enhanced specific capacity of 118.8 mA h g−1 at 0.1 A g−1 with excellent rate capability and improved cycling stability over 4000 cycles in an organic Li ion conducting electrolyte. Furthermore, the obtained porous carbon was employed as a cathode paired with a Fe3O4@C anode for LIC applications, which delivers an integrated high energy density of 124.7 W h kg−1 and a power density of 16u2006984 W kg−1 as well as a superior capacity retention of 88.3% after 2000 cycles at 5 A g−1, demonstrating the promising application as potential electrode candidates for efficient energy storage systems.