2D Graphene/MnO Heterostructure with Strongly Stable Interface Enabling High‐Performance Flexible Solid‐State Lithium‐Ion Capacitors

Abstract

The delicate structural engineering is widely acknowledged as a powerful tool for boosting the electrochemical performance of conversion-type anode materials for lithium storage. Here, a general electrostatic self-assembly strategy is proposed for the in situ synthesis of MnO nano-cabbages on negatively charged reduced graphene oxide (rGO/MnO). The strong interfacial heterostructure and robust lithium storage mechanism related to fast Li + diffusion kinetics and high Li-adsorption ability of rGO/MnO heterostructure are confirmed through operando experimental characterizations and theoretical calculation. Owing to the rapid charge transfer, enriched reaction sites, and stable heterostructure, the as-synthesized rGO/MnO anode delivers a high capacity (860 mAh g −1 at 0.1 A g −1 ), superior rate capability (211 mAh g −1 at 10 A g −1 ), and cycle stability. Notably, the as-assembled flexible pouch cell of activated carbon//rGO/MnO solid-state lithium-ion capacitors (LICs) possesses an exceptional energy density of 194 Wh kg −1 and power density of 40.7 kW kg −1 , both of which are among the highest flexible solid-state LICs reported so far. Further, the LICs possess an ultralong life span with ≈77.8% retention after 10 000 cycles and extraordinary safety, demonstrative of great potential for practical applications.

Advanced Two-Dimensional Layered Compound-Based Materials for High Performance Lithium/Sodium-Ion Capacitors

“…Among various 2D nanomaterials, transition metal oxide (TMO) has some special physical and chemical properties, such as high temperature superconductivity and multiferroics, as well as unique optical, mechanical, and thermal phenomena, which have been commercially applied in electrochemical and electronic systems. 41,109,110 ■ 2D TRANSITION METAL OXIDE AS ANODE…”

Enabling rapid pseudocapacitive multi-electron reactions by heterostructure engineering of vanadium oxide for high-energy and high-power lithium storage

“…16–18 Moreover, coupling two different nanosheets to form heterostructures could generate heterogeneous interfaces with a built-in electric field, thus accelerating interfacial charge transfer. 19–21 More importantly, with substantially improved electron and ion transport by rational nanostructuring, the electrochemical signature of a battery material can be transformed into a pseudocapacitive one, which is free from solid-state diffusion limitation and exhibits rapid surface-controlled kinetics. 22,23 In particular, a pseudocapacitive reaction with greater than one-electron redox is extremely attractive due to its ability to achieve high capacity and rate capability simultaneously, which, however, has been rarely reported and remains highly challenging owing to the increased complexity in both thermodynamics and kinetics.…”

Metal–organic frameworks and their derivatives for metal-ion (Li, Na, K and Zn) hybrid capacitors

“…32 A great deal of effort has been made to resolve the imbalance in capacity and kinetics. 33–37 For battery-type anodes, it is necessary to develop advanced nanostructures that facilitate ion diffusion to improve sluggish kinetics. 38–40 Meanwhile, electronic conductivity and stability as important indicators also need to be considered.…”