Facile Construction of Hierarchical TiNb2O7/rGO Nanoflower With Robust Charge Storage Properties for Li Ion Batteries via an Esterification Reaction

Lei Hu,Jiajia Li,Yumeng Chen,Lili Wang,Yujie Tang,Xulai Yang,Haitao Zhang

doi:10.3389/fenrg.2021.794527

Abstract

TiNb2O7 (TNO) compound has been pursued tremendously due to its high theoretical capacity, high potential, and excellent cycle stability. Unfortunately, an intrinsic low electronic and ionic conductivity feature has restricted its broad applications in electrochemical energy storage fields. Two-dimensional (2D) nanostructures can effectively shorten Li-ion transport path and enhance charge transfer. Here, hierarchical structure TNO was constructed by using ethanol and acetic acid as particularly important organic chemicals of basic raw materials via a simple solvothermal reaction. Ethanol was found to play a critical role in the formation of 2D sheet structure. Meantime, reduced graphene oxide nanosheets can effectively improve electronic conductivity. As-obtained TiNb2O7 were wrapped further by graphene oxide nanosheets through a flocculation process. Their unique structure is beneficial to the final electrochemical performance. This study not only provides a general approach for the design of novel 2D nanomaterials wrapped by graphene because of the advantage of esterification reaction and flocculation reaction, but also improves the electronic and ionic conductivity simultaneously.

Highlights

Lithium ion batteries (LIBs) have shown great potential in portable devices and electric vehicles owing to their high energy and power densities (Yang et al, 2020; Baek et al, 2021; Hu et al, 2021; Liu et al, 2021a; Zhang et al, 2021a; Zhang et al, 2021b; Guo et al, 2021; He et al, 2021)
We introduced polyacrylamide (PAM) as a binder that provides the attachment mechanism between graphene oxide (GO) and TNO
A graphene oxide (GO) and TNO particles are well-dispersed in an aqueous solution to form a homogeneous suspension and subsequently added 1% PAM gel solution

Summary

INTRODUCTION

Lithium ion batteries (LIBs) have shown great potential in portable devices and electric vehicles owing to their high energy and power densities (Yang et al, 2020; Baek et al, 2021; Hu et al, 2021; Liu et al, 2021a; Zhang et al, 2021a; Zhang et al, 2021b; Guo et al, 2021; He et al, 2021). Previous reports (Fu et al, 2014; Kumar and Sahay, 2019) suggest that the addition of alcoholysis of NbCl5 can modulate the surrounding chemical environment, and the introduction of acetic acid as a hydrolysis and condensing agent can lead to the formation of complex via a reaction with alkoxide, make the alkoxide to be nucleated more uniformly, and effectively hinder the hydrolysis, and thereby prevent unexpected precipitation Based on these reactions, we have achieved the control of oriented growth of TNO materials. A compact TNO/rGO composite is formed after annealing treatment, which realizes the graphene wrapped micron-level TNO This effective carbon coating of TNO provides a conductive network of electrons, which can greatly improve robust charge storage and rapid charge-discharge capability. The structure evolution of TNO material was investigated by in situ X-ray diffraction (XRD) on the Rigaku Smart Lab at a current density of 1 C in the 2θ range from 20 to 50° with a scanning rate of 5°min−1

RESULTS AND DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT