Preparation And Research Of Electrochemical Properties Of Anode Materials For 3D Flexible TiO₂-based Lithium Ion Battery

With growing demand for low-or even zero-emission sources of energy,rechargeable lithium-ion batteries,as an attractive power source,have received widespread attention in the past decades.Researchers persevere in optimizing lithium-ion materials to meet people's needs for high-performance lithium-ion batteries.Titanium dioxide?Ti O₂?is an attractive host material for these nanoheterostructures because of its advantages of low cost,nontoxicity,relatively high discharge potential,and negligible volume change upon cycling.Its lower theoretical capacity(about 168 m Ahg^-1)can be offset by hybridization with other oxide materials that have large theoretical capacity.Electrochemically active one-dimensional?1D?hollow nanoarrays with high length-to-diameter ratio have been deemed to effectively enhance the rate capabilities by shortening the lithium-ions diffusion path.Additionally,two-dimensional?2D?single-layer nanosheets with reasonable arrangements impart electrodes with excellent electronic properties as a result of their large effective contact area and high tolerance to volume variations.Under large surface-to-volume ratios and synergic effects,incorporating multiple 1D hollow nanoarrays and 2D nanosheets into well-defined three-dimensional?3D?nanoheterostructure arrays can provide anode materials with high power capabilities.Therefore,it is predicted that the fabrication of 3D nanocomposites by coating 2D nanosheets on the core of Ti O₂ hollow nanofiber arrays would be an effective mitigation strategy toward achieving high-performance rechargeable batteries.With the increasing demand for flexible and bendable electronic devices,flexible energy storage devices have been extensively studied.Fabrication of nanostructured arrays on carbon cloth?CC?substrates also has become more mainstream,particularly given the enhanced conductivity as well as the freestanding binder-free characteristics,good flexibility,stability,and excellent mechanical properties.With this superior combination of flexible carbon fiber cloth?CC?and three-dimensional nanoheterostructure arrays is expected to be applied to the next generation of lithium ion batteries with high energy density.In this paper,the preparation and electrochemistry properties of flower-like 3D flexible CC/Ti O₂@Zn O and Ni O@Ti O₂/CC were studied.The specific work is as follows:?1?The flexible three-dimensional hierarchical carbon cloth?CC?/Ti O₂@Zn O hollow nanoflower arrays are synthesized in facile seed-free solvothermal method,chemical thermal bath method and annealing.This composite nanostructure with a lavender-like shell has a large specific surface area.The mesoporous hollow architecture and the direct contact with the CC current collector impart the as-prepared electrodes an efficient electronic pathway.The electrochemical measurements indicate that the flexible three-dimensional hierarchical CC/Ti O₂@Zn O hollow nanoflower arrays show high-rate capability,prominent specific capacity,and long-term cyclic performance because of their unique hierarchical structure.Even after 200 cycles at a current density of 200 m Ag^-1,the capacity retention of the flexible three-dimensional hierarchical CC/Ti O₂@Zn O hollow nanoflower arrays is still up to 846 m Ahg^-1.?2?The transversally staggered 3D binder-free Ni O@Ti O₂ flower-like nanotube network arrays on carbon cloth substrates are synthesized through a simple two-process,seed-free solvothermal method and annealing to meet the escalating demands for flexible devices operated steadily under mechanical deformation.Their porous hollow inner and binder-free peculiarity ensure an expedite transport of lithium-ions and electrons upon cycling.The transversally staggered flower-like shells destroy the integrity of passivation layers,leading to a remarkable reduce in the irreversible capacity loss without sacrifice of the specific surface area.Even after 200 cycles at a current density of 200 m Ag^-1,this unique structure keeps a specific capacity about 736.4 m Ahg^-1 and rate capacity of 439m Ahg^-1 even at high current densities of 2000 m Ag^-1.Their full cells maintain excellent electrochemical performance even following serious bend.