Strategies for improving the lithium-storage performance of 2D nanomaterials

Abstract

2D nanomaterials, including graphene, transition metal oxide (TMO) nanosheets, transition metal dichalcogenide (TMD) nanosheets, etc., have offered an appealing and unprecedented opportunity for the development of high-performance electrode materials for lithium-ion batteries (LIBs). Although significant progress has been made on 2D nanomaterials for LIB applications in the recent years, some major challenges still exist for the direct use of these sheet-like nanomaterials, such as their serious self-agglomerating tendency during electrode fabrication and low conductivity as well as the large volume changes over repeated charging–discharging cycles for most TMOs/TMDs, which have resulted in large irreversible capacity, low initial Coulombic efficiency and fast capacity fading. To address these issues, considerable progress has been made in the exploitation of 2D nanosheets for enhanced lithium storage. In this review, we intend to summarize the recent progress on the strategies for enhancing the lithium-storage performance of 2D nanomaterials, including hybridization with conductive materials, surface/edge functionalization and structural optimization. These strategies for manipulating the structures and properties of 2D nanomaterials are expected to meet the grand challenges for advanced nanomaterials in clean energy applications and thus provide access to exciting materials for achieving high-performance next-generation energy-storage devices.

Honeycomb‐Inspired Heterogeneous Bimetallic Co–Mo Oxide Nanoarchitectures for High‐Rate Electrochemical Lithium Storage

“…in the exploration and design of favorable electrode materials with optimized composition and structure for boosting lithium ion storage is still a focus of related cutting‐edge fields . Rational design of nanostructured electrode nanomaterials, which possess the properties to enhance reaction kinetics, accommodate structural strains, facilitate rapid mass transport paths, and enlarge ion storage sites and interfaces, have been shown to be an exciting approach to boost the performance of energy storage devices . Unfortunately, some electrochemically favorable nanostructures lose their structural integrity during cycles and finally result in sluggish electrochemical reactions and rapid decay of capacity, particularly at high rates .…”

“…Unfortunately, some electrochemically favorable nanostructures lose their structural integrity during cycles and finally result in sluggish electrochemical reactions and rapid decay of capacity, particularly at high rates . Therefore, how to maintain structurally stable nanostructures with enhanced electrochemical performances is another research target for high‐rate energy storage devices …”

Toward Promising Cathode Catalysts for Nonlithium Metal–Oxygen Batteries

“…Apart from the carbon‐based catalysts, the conductive polymer materials have also been exploited to catalyze ORR for these batteries . For example, a biodegradable silk fibroin‐polypyrrole (SF‐PPy) film has been designed as the oxygen catalytic electrode for Mg–O 2 batteries .…”

“…In order to improve their OER activity and further enhance the ORR activity, modification of their surface electronic structures has been regarded as one of the most simple, straightforward, and cost‐effective strategy to induce the desirable OER/ORR activity on carbons . On the other hand, the actual catalytic activity of these doped carbons can also be enhanced by the rational design of various pore structures, which can simultaneously increase the surface area and active site numbers, improve the mass transport, and finally facilitate the kinetics of the catalysis processes …”

“…The rapid development of lithium ion batteries (LIBs) offers an unprecedented opportunity to meet the increasing requirements for the various electric/electronic devices. The limited energy density of LIBs (≈400 Wh kg −1 ) and their unsatisfying safety, unfortunately, are the major challenges for further expanding their practical application in the various potential fields, such as electric vehicles (EVs) with a long driving range . Even though the energy density can be considerably enhanced by replacing the current Li‐ion configuration into a Li–O 2 configuration that directly utilizes lithium metal and oxygen gas as the anode and cathode active species, there is still no doubt that the safety and cost issues can hardly be overcome due to the unavoidable involvement of scarce metallic lithium in these Li‐based battery chemistries .…”