Font Size: a A A

Synthesis Of Hierarchical TiO2-Based Free-Standing Films For High-Performance Lithium/Magnesium Ion Batteries

Posted on:2021-12-17Degree:DoctorType:Dissertation
Country:ChinaCandidate:C DongFull Text:PDF
GTID:1361330632950691Subject:Materials Science and Engineering
Abstract/Summary:PDF Full Text Request
Novel nanomaterials with high specific capacity show great potential to replace commercial electrode materials.However,the aggregation and volumetric variation of these electrode materials during the charge-discharge process lead to the low rate performance and poor cycling stability.Therefore,an efficient strategy is proposed to assemble TiO2-based free-standing films for high performance lithium/magnesium ion batteries.The strategy paves the way for disighing and preparing novle electrode materials with high capacity,excellent rate performance and superior cycling stability.The research work of this thesis includes the following four parts.(1)An efficient strategy is proposed to assemble defect-rich TiO2(B)nanosheets into a 3D-scaffold structured free-standing film,which can preserve high chemical activity and prevent their aggregation.The inherent pores of Teflon lining are employed as load-bearing base to construct 3D scaffolds,and then,a rapid dissolution-recrystallization hydrothermal process is developed to fabricate defect-rich TiO2(B)nanosheets on the 3D scaffolds.Given the numerous defects,enormous exposed surface and characteristic interpenetrating nanosheet scaffolds,defect-rich TiO2(B)nanosheets-based binder-and substrate-free electrode exhibits high rate capability and superior cycling stability in Lithium ion batteries.(2)TiO2@SnO2@C free-standing films with core-sheath structure are synthesized by one-pot hydrothermal reaction,which employing the titanate free-standing films as template.SnO2 nanoparticles are anchored on the stable TiO2 scaffolds.The co-deposition of C and SnO2 prevents the aggregattion of SnO2 nanoparticles and protects it effectively,which endows the composite electrode with excellent cycling stability.(3)A Teflon column with storage room is employed in the pressure induced hydrothermol reaction to release raw materials gradually and boost the assembly of nanohelical titanate frameworks.Based on the frameworks,nanohelical TiO2@Co3O4@CNTs core-sheath flexible films are synthesized,which contain nanohelical TiO2 skeleton,hollow Co3O4 nanoparticles and CNT networks.The mechanical stress caused by Co3O4 volumetric variation is successfully exported into the nanohelical frameworks via spring-like free stretching,which endows the electrode with superior cycling stability.(4)Bimetallic MOFs are employed as precursors to prepare cubic MgMn2O4 nanomaterials at low temperature.As a cathode materials for magnesium ion batteries,the MgMn2O4 electrode shows excellent cycling stability owing to its ordered nanoparticle stacking and broadened ion inserted channels.In addition,the MgMn2O4 electrode materials are activated in the early period of charge-discharge processes,leading to gradually increased specific capacity and more obvious charge-discharge platform.
Keywords/Search Tags:TiO2, Metal organic frameworks, Free-standing films, Hydrothermal reactions, Lithium ion batteries
PDF Full Text Request
Related items