The role of graphene aerogels in rechargeable batteries

Energy storage systems, particularly rechargeable batteries, play a crucial role in establishing a sustainable energy infrastructure. Today, researchers focus on improving battery energy density, cycling stability, and rate performance. This involves enhancing existing materials or creating new ones with advanced properties for cathodes and anodes to achieve peak battery performance. Graphene aerogels (GAs) possess extraordinary attributes, including a hierarchical porous and lightweight structure, high electrical conductivity, and robust mechanical stability. These qualities facilitate the uniform distribution of active sites within electrodes, mitigate volume changes during repeated cycling, and enhance overall conductivity. When integrated into batteries, GAs expedite electron/ion transport, offer exceptional structural stability, and deliver outstanding cycling performance. This review offers a comprehensive survey of the advancements in the preparation, functionalization, and modification of GAs in the context of battery research. It explores their application as electrodes and hosts for the dispersion of active material nanoparticles, resulting in the creation of hybrid electrodes for a wide range of rechargeable batteries including lithium-ion batteries (LIBs), Li-metal-air batteries, sodium-ion batteries (SIBs), zinc-ion batteries (AZIBs) and zinc-air batteries (ZABs), aluminum-ion batteries (AIBs) and aluminum-air batteries and other.

Dual Network Sponge for Compressible Lithium-Ion Batteries

Compressible energy devices have received increasing attention with the rapid development of flexible electronics and wearable devices due to their size adaptability and functional stability. However, it is hard to simultaneously achieve satisfactory energy density and mechanical stability for electrodes. Here an open-porous dual network sponge (DNS) with two networks of highly conductive carbon nanotubes and Li⁺ -intercalating TiO₂ -B nanowires is synthesized and employed as compressible lithium ion battery electrodes. All 1D components inside the DNS mutually penetrate with each other to form two physically distinct but functionally coupling networks, endowing DNS excellent compressibility and stability. A prototype compressible lithium-ion battery (C-LIB) is also demonstrated, in which the DNS exhibits a specific capacity of >238 mAh g^-1 under static 50% strain, and further in situ measurements show that under 1000 times of cyclic strains, DNS can charge and discharge normally maintaining a high capacity of 240 mAh g^-1 and exhibits robustness to fast strain rates up to 500% min^-1 . The dual network structure can be extended to design high-performance compliant electrodes that are promising to serve in future compressible and deformable electronics and energy systems.

Three-dimensionally ordered mesoporous multicomponent (Ni, Mo) metal oxide/N-doped carbon composite with superior Li-ion storage performance

Among the various nanostructures, porous materials with controlled pore structures have been widely used for designing transition metal-based anode materials for lithium-ion batteries, because they provide good access to electrolyte and can effectively accommodate stress arising from volume changes. In particular, ternary transition metal oxide materials containing nanovoids, arranged with high degree of periodicity, are ideal for enhancing lithium-ion storage capability. In this study, we provide a method using spray pyrolysis for the synthesis of mesoporous multicomponent metal oxide microspheres containing Ni and Mo components and N-doped carbon, in which three-dimensionally ordered 40 nm-sized mesopores are interconnected. During the synthesis, polystyrene nanobeads are used as a sacrificial template and are readily eliminated via thermal decomposition. Increased concentrations of polystyrene nanobeads enables the formation of open channels throughout the microspheres. When employed as a lithium-ion battery anode, the mesoporous multicomponent metal oxide microspheres containing Ni and Mo components and N-doped carbon exhibit high reversible capacity, good cycling stability, and excellent rate performance. After 1000 cycles, the microspheres deliver a discharge capacity of 693 mA h g^-1 at a current density of 1.0 A g^-1.

Graphene: a promising 2D material for electrochemical energy storage

Graphene, with unique two-dimensional form and numerous appealing properties, promises to remarkably increase the energy density and power density of electrochemical energy storage devices (EESDs), ranging from the popular lithium ion batteries and supercapacitors to next-generation high-energy batteries. Here, we review the recent advances of the state-of-the-art graphene-based materials for EESDs, including lithium ion batteries, supercapacitors, micro-supercapacitors, high-energy lithium-air and lithium-sulfur batteries, and discuss the importance of the pore, doping, assembly, hybridization and functionalization of different nano-architectures in improving electrochemical performance. The major roles of graphene are highlighted as (1) a superior active material, (2) ultrathin 2D flexible support, and (3) an inactive yet electrically conductive additive. Furthermore, we address the enormous potential of graphene for constructing new-concept emerging graphene-enabled EESDs with multiple functionalities of lightweight, ultra-flexibility, thinness, and novel cell configurations. Finally, future perspectives and challenges of graphene-based EESDs are briefly discussed.

Fabrication of Co3O4 nanoparticles in thin porous carbon shells from metal–organic frameworks for enhanced electrochemical performance

Ultrasmall Co₃O₄ nanoparticle with thin porous carbon shell is reported by employing metal–organic framework as precursor and CO₂ as oxidizing atmosphere, which exhibits a long cycling stability and high rate performance for Li-ion battery.

Nitrogen-doped carbon and high-content alumina containing bi-active cobalt oxides for efficient storage of lithium

Low-content ultrathin coating of non-active alumina (Al2O3) has been extensively utilized as one of the most effective strategies to improve electrochemical performances of electrodes for lithium-ion batteries (LIBs), however, typically by employing expensive atomic layer deposition equipment. We herein demonstrate a simple preparation of high-content and well-dispersed Al2O3 (24.33wt.%)-containing multi-component composite (CoO/Co3O4/N-C/Al2O3) by calcination of melamine/CoAl-layered double hydroxide (CoAl-LDH) mixture. The resulting composite bundles the advantages expected to improve electrochemical performances: (i) bi-active CoO/Co3O4, (ii) highly conductive N-doped carbon, and (iii) N-doped carbon and high-content non-active Al2O3 as buffering reagents, as well as (iv) good distribution of bi- and non-active components resulted from the lattice orientation and confinement effect of the LDH layers. Electrochemical evaluation shows that the composite electrode delivers a highly enhanced reversible capacity of 1078mAhg(-1) after 50cycles at 100mAg(-1), compared with the bi-active CoO/Co3O4 mixtures with and without non-active Al2O3. Transmission electron microscopy/scanning electron microscopy observations and electrochemical impedance spectra experimentally provide the information on the good distributions of multiple components and the improved conductivity underlying the enhancements, respectively. Our LDH precursor-based preparation route may be extended to design and prepare various multi-component transition metal oxides for efficient lithium storage.

Facile one-step synthesis of highly graphitized hierarchical porous carbon nanosheets with large surface area and high capacity for lithium storage

Hierarchical porous carbon nanosheets with both high graphitization degree and large specific surface area were prepared and applied as anode for lithium storage, exhibiting a high reversible discharge capacity.

Novel synthesis of RGO/NiCoAl–LDH nanosheets on nickel foam for supercapacitors with high capacitance

Hierarchically flower-like RGO/NiCoAl–LDH@NF hybrid has been fabricated by a facile, green approach, giving a high electrochemistry performance with high and stable specific capacitance.

In Situ Activation of Nitrogen-Doped Graphene Anchored on Graphite Foam for a High-Capacity Anode

We report the fabrication of a three-dimensional free-standing nitrogen-doped porous graphene/graphite foam by in situ activation of nitrogen-doped graphene on highly conductive graphite foam (GF). After in situ activation, intimate "sheet contact" was observed between the graphene sheets and the GF. The sheet contact produced by in situ activation is found to be superior to the "point contact" obtained by the traditional drop-casting method and facilitates electron transfer. Due to the intimate contact as well as the use of an ultralight GF current collector, the composite electrode delivers a gravimetric capacity of 642 mAh g(-1) and a volumetric capacity of 602 mAh cm(-3) with respect to the whole electrode mass and volume (including the active materials and the GF current collector). When normalized based on the mass of the active material, the composite electrode delivers a high specific capacity of up to 1687 mAh g(-1), which is superior to that of most graphene-based electrodes. Also, after ∼90 s charging, the anode delivers a capacity of about 100 mAh g(-1) (with respect to the total mass of the electrode), indicating its potential use in high-rate lithium-ion batteries.

Influence of electrolyte additives on a cobalt oxide-based anode's electrochemical performance and its action mechanism

The influences of different additives on the LIBs electrodes were investigated in detail. The action mechanism of SEI films between additives and CoO composites were confirmed too.

Fabrication of a high density graphene aerogel–gold nanostar hybrid and its application for the electrochemical detection of hydroquinone and o-dihydroxybenzene

We report the first synthesis of a high density graphene aerogel–gold nanostar hybrid with excellent mechanical and electrical properties and its application in the electrochemical detection of hydroquinone and o-dihydroxybenzene.