Preparation Of Layered Vanadate-based Integrated Hybrid Electrode And Its Application In Ion Batteries

Lithium-ion batteries（LIBs）dominate the rechargeable battery market in virtue of their high energy density and long cycle life,and are widely used in various electronic devices.Sodium-ion batteries（SIBs）are considered as a competitive alternative to LIBs in the field of large-scale energy storage due to their advantages in cost and safety.However,they are both limited by the low theoretical specific capacity(only～372 mAh g^–1)of the carbon-based anode,which makes it difficult to meet the ever-growing demand for high-density energy storage.Therefore,the exploration of novel electrode materials with high specific capacity is essential to achieve high-density energy storage.Vanadates have received much attention due to their structural diversity,high electrochemical activity and high specific capacity.Among them,the unique layer structure of layered vanadates facilitates the storage and diffusion of energy storage ions between the layers.However,the limited interlayer spacing is not conducive to the repeated embedding and disembedding of ions during cycling,which easily causes structural damage and affects the stability and lifespan of the batteries.Pre-intercalation is considered as a common strategy to expand the interlayer spacing and optimize the ion storage performance of the layered materials.The commonly used intercalation guests are mainly Li⁺,Na⁺,Ca²⁺,and Al³⁺ions.However,the pre-intercalated ions are difficult to maintain stable during the repeated charging and discharging,and their intrinsic sizes limit the extent of interlayer spacing expansion.Pre-intercalating tunable organic molecular to expand the interlayer spacing of the host materials can provide an effective strategy for ion storage,thus achieving fast,reversible and stable ion diffusion kinetics.Therefore,in order to achieve elastic tuning of the interlayer spacing and obtain electrode materials that are favorable for ion transport,the research in this thesis is as follows:（1）The vanadate material（H₃N（CH₂）₃NH₃）[V₄O₁₀]（denoted as PDA-VO）was prepared by pre-intercalating 1,3-propanediamine as a pillar into the interlayer of vanadium oxide,and（2）1,4-butanediamine and 1,6-hexanediamine with longer carbon chains were used as pre-intercalating guests to further expand the interlayer spacing of vanadium oxide to meet the needs of sodium-ion batteries,and the elastic regulation of the interlayer spacing was successfully achieved,with a linear relationship between the carbon chain length of the pre-intercalated guests and the interlayer spacing.In addition,thanks to the serrated V–O layer structure and the extended interlayer spacing,the sodium-ion battery based on（H₃N（CH₂）₆NH₃）[V₆O₁₄]/NF（denoted as HDA-VO/NF）electrode provides a specific capacity of up to 597 mAh g^–1 at a current density of 0.09 A g^–1,which is better than most recently reported vanadium-based materials.The Galvanostatic intermittent titration technique（GITT）test results show that the HDA-VO/NF electrode has a fast ion diffusion rate,and Density functional theory（DFT）calculations reveal and explain its ion transport kinetics.