All‐Graphene Quantum Dot‐Derived Battery: Regulating Redox Activity Through Localized Subdomains

Abstract

In the quest for materials sustainability for grid‐scale applications, graphene quantum dot (GQD), prepared via eco‐efficient processes, is one of the promising graphitic‐organic matters that have the potential to provide greener solutions for replacing metal‐based battery electrodes. However, the utilization of GQDs as electroactive materials has been limited; their redox behaviors associated with the electronic bandgap property from the sp2 carbon subdomains, surrounded by functional groups, are yet to be understood. Here, the experimental realization of a subdomained GQD‐based anode with stable cyclability over 1000 cycles, combined with theoretical calculations, enables a better understanding of the decisive impact of controlled redox site distributions on battery performance. The GQDs are further employed in cathode as a platform for full utilization of inherent electrochemical activity of bio‐inspired redox‐active organic motifs, phenoxazine. Using the GQD‐derived anode and cathode, an all‐GQD battery achieves a high energy density of 290 Wh kgcathode−1 (160 Wh kgcathode+anode−1), demonstrating an effective way to improve reaction reversibility and energy density of sustainable, metal‐free batteries.

Lithium Pre‐Storage Enables High Initial Coulombic Efficiency and Stable Lithium‐Enriched Silicon/Graphite Anode

“…And the peak of ‐COOLi shifts to 1401 cm −1 in LESG, similar to the EELS results [35] . Furthermore, Time‐of‐Flight Secondary Ion Mass Spectrometry (TOF SIMS) also reveals the presence of COOLi in LEG (Figure S8) [36] . Therefore, it is inferred that Li elements are incorporated into the graphite as COOLi during the lithium pre‐storage process.…”

Lithium Pre‐Storage Enables High Initial Coulombic Efficiency and Stable Lithium‐Enriched Silicon/Graphite Anode

“…[35] Furthermore, Time-of-Flight Secondary Ion Mass Spectrometry (TOF SIMS) also reveals the presence of COOLi in LEG (Figure S8). [36] Therefore, it is inferred that Li elements are incorporated into the graphite as COOLi during the lithium pre-storage process. Both EELS and FTIR analyses indicate a lower bond energy for COOLi in LESG compared to LEG.…”

Engineering functionalization and properties of graphene quantum dots (GQDs) with controllable synthesis for energy and display applications

“…Moreover, recent research has reported controlled redox sites in LIBs where GQDs are introduced into every component of the battery. 29 In this study, the anode was prepared through π–π stacking between non-oxidized graphene flakes (NOGF) and GQDs, while the cathode was prepared through the selective esterification reaction between the carboxyl groups of GQDs and phenoxazine (PXZ). This resulted in a metal-free battery with an energy density of 290 W h kg cathode −1 (160 W h kg cathode+anode −1 ) and stable cycling for over 1000 cycles.…”

“…17–19 Moreover, GQDs exhibit outstanding reactivity based on solvent dispersibility and physicochemical adsorption capabilities. 20,21 As a result, GQDs have garnered significant attention in various applications, including biotechnology, 22–24 water purification, 25,26 catalysis, 20,27,28 energy storage, 29–32 and displays. 33,34…”