机械化学法合成钛钒赝二元系及其与锂钠的转化反应
Mechanochemical synthesis of pseudobinary Ti-V hydrides and their conversion reaction with Li and Na
摘要：
基于插入电极的锂离子电池（LiB）达到固有容量极限。性能的提高和成本的降低需要替代的反应机制和新的电池化学，如转换反应和钠离子电池（NaB），分别。本文研究了Ti_（1-x）H_2O（0 <x <1）的形成及其在LiB和NaB半电池中作为阳极的电化学性能。在氢气气氛下（PH2~8MPa），利用机械力化学法合成了氢化物。对于V含量低于80 at. %（x <0.8），形成单相准二元二氢化物Ti_（1-x）H_2。它们以萤石型结构结晶，具有高度纳米结构（微晶尺寸<10 nm）。它们的晶格常数随V含量线性减小，导致氢化物失稳。电化学研究首先在Li离子半电池中进行，其中Ti 1-xH2+和锂之间完全转化。转化反应的电势可以随着钒含量而逐渐调整，这是由于钒的去稳定作用。此外，富Ti（x <0.25）和富V（x> 0.7）合金的转化反应路径不同。Na离子半电池测量证明了（V，Ti）H2+和钠之间的反应性，尽管具有显著的动力学限制
英文摘要：
Lithium-ion batteries (LiBs) based on insertion electrodes reach intrinsic capacity limits. Performance improvements and cost reduction require alternative reaction mechanisms and novel battery chemistries such as conversion reactions and sodium-ion batteries (NaBs), respectively. We here study the formation of Ti1-xVxH2 hydrides (0 < x < 1) and their electrochemical properties as anodes in LiBs and NaBs half-cells. Hydrides were synthesized by mechanochemistry of the metal powders under hydrogen atmosphere (PH2~ 8 MPa). For V contents below 80 at.% (x < 0.8), single-phase pseudobinary dihydride compounds Ti1-xVxH2 are formed. They crystallize in the fluorite-type structure and are highly nanostructured (crystallite size < 10 nm). Their lattice parameter decreases linearly with the V content leading to hydride destabilization. Electrochemical studies were first carried out in Li-ion half cells with full conversion between Ti1-xVxH2 hydrides and lithium. The potential of the conversion reaction can be gradually tuned with the vanadium content due to its destabilization effect. Furthermore, different paths for the conversion reaction are observed for Ti-rich (x < 0.25) and V-rich (x > 0.7) alloys. Na-ion half-cell measurements prove the reactivity between (V,Ti)H2 hydrides and sodium, albeit with significant kinetic limitations
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