Boosting the Energy Density of Bowl ‐Like MnO2@Carbon Through Lithium‐Intercalation in a High‐Voltage Asymmetric Supercapacitor with “Water‐In‐Salt” Electrolyte

MnO2 nanoflowers are successfully grown on mesoporous bowl-like carbon (MBC) particles to generate MnO2/MBC composite, which can largely improve the electrochemical performance. An asymmetric supercapacitor MnO2/MBC//AC device in 21  m LiTFSI electrolyte involves the occurrence of reversible reactions ofMnO2 +xLi+ +xe−↔LixMnO2 on charging and discharging, which greatly enhances the energy density of MnO2/MBC//AC device. AbstractHighly concentrated “‘water-in-salt”’ (WIS) electrolytes are promising for high-performance energy storage devices due to their wide electrochemical stability window. However, the energy storage mechanism of MnO2 in WIS electrolytes-based supercapacitors remains unclear. Herein, MnO2 nanoflowers are successfully grown on mesoporous bowl-like carbon (MBC) particles to generate MnO2/MBC composites, which not only increase electroactive sites and inhibit the pulverization of MnO2 particles during the fast charging/discharging processes, but also facilitate the electron transfer and ion diffusion within the whole electrode, resulting in significant enhancement of the electrochemical performance. An asymmetric supercapacitor, assembled with MnO2/MBC and activated carbon (AC) and using 21  m LiTFSI solution as the WIS electrolyte, delivers an ultrahigh energy density of 70.2  Wh kg−1 at 700  W kg−1, and still retains 24.8  Wh kg−1 when the power density is increased to 28  kW kg−1. The ex situ XRD, Raman, and XPS measurements rev...

Source: Small - April 18, 2024 Category: Nanotechnology Authors: Yudan Qian, Zhiming Zhou, Qingcheng Zhang, Huaping Zhao, Heng Chen, Jintong Han, Haiting Wan, Huile Jin, Shun Wang, Yong Lei Tags: Research Article Source Type: research