New Insight into the Mechanism of Multivalent Ion Hybrid Supercapacitor: From the Effect of Potential Window Viewpoint

Abstract

Multivalent ion hybrid supercapacitors have been developed as the novel electrochemical energy storage systems due to their combined merits of high energy density and high power density. Nevertheless, there are still some challenges due to the limited understanding of the electrochemical behaviors of multivalent ions in the electrode materials, which greatly hinders the large scale applications of its based hybrid supercapacitors. Herein, the long‐term electrochemical behaviors of MnO2‐based electrode in the divalent Mg2+ ions electrolyte are systematically studied and linked with the morphological and electronic evolution of MnO2 by cycling at different potential windows (spanning to 1.2 V). It reveals that the different potential windows result in the different electrochemical behaviors, which can be divided into two ranges (below and above −0.2 V). And, the electrode cycled at a potential window of 0–1.2 V delivers the highest capacitance of 967 F g−1 at a scan rate of 10 mV s−1, in which the MnO2 is transformed into a uniformly distributed and nonagglomerated nanoflake morphology promoting the intercalation and deintercalation of Mg2+ ions. This study will enrich the understanding of the charge storage mechanism of multivalent ions and provide significant guidance on the performance improvement of the hybrid supercapacitors.

Atomically Thin Materials for Next-Generation Rechargeable Batteries

“…Batteries based on multivalent metals are promising alternatives to LIBs due to the abundance of elements in the Earth’s crust, high volumetric energy density, and safe operation . However, due to the strong polarization of multivalent cations, their diffusion within the electrode is extremely slow, which undoubtedly leads to sluggish intercalation/deintercalation kinetics, irreversible storage capacity, and inferior rate performance. , Therefore, developing cathode materials with high voltage and high capacity holds the key to overcoming the bottleneck of current multivalent-ion batteries . With the advantages of atomic thickness, easily tuned electronic properties, high mechanical strength, and high flexibility, ATMs are promising cathode materials for multivalent-ion batteries.…”

Co-doped MnO2 with abundant oxygen vacancies as a cathode for superior aqueous magnesium ion storage

“…can realize a wide working voltage from ∼1.6 to 2.0 V, which is another promising strategy to improve the energy density of waterborne ASCs. [41][42][43] Among them, the abundant resources and the possibility of processing metals in the surrounding environment lower the cost of Mg. 44,45 Moreover, the insertion/desorption of divalent Mg 2+ provides the advantage of each ion charging two electrons to the battery-type material and offers high specific energy. 46,47 More importantly, Mg 2+ has a similar radius and electrochemical properties to Li + , but it displays better chemical stability and lower electrode potential in the atmospheric environment.…”

Biomass-Derived Carbon Materials for Advanced Metal-Ion Hybrid Supercapacitors: A Step Towards More Sustainable Energy

“…Bunker and his colleague's work on materials such as ZHSCs and PIHCs attempts to understand a battery that delivers optimal functionality [21,38]. Furthermore, researchers have created multivalent-ion HSCs to attain elevated energy and power densities [39]. MIHSCs constitute a significant advancement in energy storage technology that combines the benefits of batteries and supercapacitors.…”