2D MXene-based nanomaterials have attracted tremendous attention because of their unique physical/chemical properties and wide range of applications in energy storage, catalysis, electronics, optoelectronics, and photonics. However, MXenes and their derivatives have many inherent limitations in terms of energy storage applications. In order to further improve their performance for practical application, the nanoengineering of these 2D materials is extensively investigated. In this Review, the latest research and progress on 2D MXene-based nanostructures is introduced and discussed, focusing on their preparation methods, properties, and applications for energy storage such as lithium-ion batteries, sodium-ion batteries, lithium-sulfur batteries, and supercapacitors. Finally, the critical challenges and perspectives required to be addressed for the future development of these 2D MXene-based materials for energy storage applications are presented.

Nanoengineering of 2D MXene-Based Materials for Energy Storage Applications

The development of sodium-ion batteries for large-scale applications requires the synthesis of electrode materials with high capacity, high initial Coulombic efficiency (ICE), high rate performance, long cycle life, and low cost. A rational design of freestanding anode materials is reported for sodium-ion batteries, consisting of molybdenum disulfide (MoS2) nanosheets aligned vertically on carbon paper derived from paper towel. The hierarchical structure enables sufficient electrode/electrolyte interaction and fast electron transportation. Meanwhile, the unique architecture can minimize the excessive interface between carbon and electrolyte, enabling high ICE. The as-prepared MoS2@carbon paper composites as freestanding electrodes for sodium-ion batteries can liberate the traditional electrode manufacturing procedure, thereby reducing the cost of sodium-ion batteries. The freestanding MoS2@carbon paper electrode exhibits a high reversible capacity, high ICE, good cycling performance, and excellent rate capability. By exploiting in situ Raman spectroscopy, the reversibility of the phase transition from 2H-MoS2 to 1T-MoS2 is observed during the sodium-ion intercalation/deintercalation process. This work is expected to inspire the development of advanced electrode materials for high-performance sodium-ion batteries.

MoS2 Nanosheets Vertically Aligned on Carbon Paper: A Freestanding Electrode for Highly Reversible Sodium Ion Batteries

Recent progress in the synthesis of graphene and derived materials for next generation electrodes of high performance lithium ion batteries

Metal-organic frameworks (MOFs), also quoted as porous coordination polymers (PCPs), are causing great concern in supercapacitors (SCs) field owing to their ultra-high surface-areas, tailorable pore-sizes and shapes, and diverse structural architectures. This review mainly focuses on the recent progress in various branches of MOFs materials including porous coordination networks, two-dimensional (2D) MOFs, entangled MOFs, polyoxometalate MOFs (POMOFs), heterometallic MOFs, and some new emerging MOFs, as well as their applications in SCs. The superiority and the deficiency of various MOF types were systematically introduced and summarized. Additionally, the challenges and perspectives relate to pristine MOFs and MOFs-based composites for the applications in SCs have also been discussed. We hope that our review could provide guiding frameworks to design and fabricate MOFs materials with more practical energy-storage applications.

Recent progress in metal-organic frameworks as active materials for supercapacitors

The rapid development of electrochemical energy storage (EES) systems requires novel electrode materials with high performance. A typical 2D nanomaterial, layered transition metal dichalcogenides (TMDs) are regarded as promising materials used for EES systems due to their large specific surface areas and layer structures benefiting fast ion transport. The typical methods for the preparation of TMDs and TMD-based nanohybrids are first summarized. Then, in order to improve the electrochemical performance of various kinds of rechargeable batteries, such as lithium-ion batteries, lithium-sulfur batteries, sodium-ion batteries, and other types of emerging batteries, the strategies for the design and fabrication of layered TMD-based electrode materials are discussed. Furthermore, the applications of layered TMD-based nanomaterials in supercapacitors, especially in untraditional supercapacitors, are presented. Finally, the existing challenges and promising future research directions in this field are proposed.

Layered Transition Metal Dichalcogenide-Based Nanomaterials for Electrochemical Energy Storage.

The invention relates to a preparation method of an SnO -TiO @ graphene ternary composite nanomaterial. By a one-step method, with pyrolyzed and reduced graphene oxide, stannous chloride hydrate (SnCl .2H O) and titanyl sulfate (TiOSO ) as raw materials, and water and ethanol as solvents, the SnO -TiO @ graphene ternary composite nanomaterial with a uniform structure is obtained under the action of hydrochloric acid by a simple hydrothermal synthesis method. From an XRD spectrogram, according to the prepared SnO -TiO @ graphene ternary composite nanomaterial, crystalline phases of two metal oxides SnO and TiO coexist in the composite material; and the SnO -TiO @ graphene ternary composite nanomaterial prepared by the method has a potential application prospect in the fields of new energy and the like.

SnO -TiO @ graphene ternary composite nanomaterial and preparation method thereof

Nanoengineering of metal anode materials shows great potential for energy storage with high capacity. Zero-dimensional nanoparticles are conducive to acquire remarkable electrochemical properties in sodium-ion batteries (SIBs) because of their enlarged surface active sites. However, it is still difficult to fulfill the requirements of practical applications in batteries owing to the deficiency of efficient and scalable preparation approaches of high-performance metal electrode materials. Herein, an electrochemical cathodic corrosion method is proposed for the tunable preparation of nanostructured antimony (Sb) by the introduction of a surfactant, which can efficiently avoid the agglomeration of Sb atom clusters generated from the Zintl compound and further stacking into bulk during the electrochemical process. Subsequently, graphene as the support and conductive matrix is uniformly interspersed by generating Sb nanoparticles (Sb/Gr). Moreover, the reversible crystalline-phase evolution of Sb ⇋ NaSb ⇋Na3Sb for Sb/Gr was studied by in situ X-ray diffraction (XRD). Benefiting from the interconnection of the conductive network, Sb/Gr anodes deliver a high capacity of 635.34 mAh g-1, a retained capacity of 507.2 mAh g-1 after 150 cycles at 0.1 C (1 C = 660 mAh g-1), and excellent rate performance with the capacities of 473.41 and 405.09 mAh g-1 at 2 and 5 C, respectively. The superior cycle stability with a capacity of 346.26 mAh g-1 is achieved after 500 cycles at 2 C. This electrochemical approach offers a new route toward developing metal anodes with designed nanostructures for high-performance SIBs.

Laiqiang Xu

Papers

SnO -TiO @ graphene ternary composite nanomaterial and preparation method thereof

Electrochemically Engineering Antimony Interspersed on Graphene toward Advanced Sodium-Storage Anodes.

Electrochemical Zintl Cluster Bi22− Induced Chemically Bonded Bismuth / Graphene oxide Composite for Sodium-Ion Batteries

In-situ construction of multifunctional interlayer enabled dendrite-free garnet-based solid-state batteries

Wood-derived carbon anode for sodium-ion batteries