A fundamental understanding of the electrochemical reaction process and mechanism of electrodes is very crucial for developing high-performance electrode materials. In this study, we report the sodium ion storage behavior and mechanism of orthorhombic V₂O₅ single-crystalline nanowires in the voltage window of 1.0–4.0 V (vs. Na/Na⁺). The single-crystalline nanowires exhibit a large irreversible capacity loss during the first discharge/charge cycle, and then show excellent cycling stability in the following cycles. At a current density of 100 mA g⁻¹, the nanowires electrode delivers initial discharge/charge capacity of 217/88 mA h g⁻¹, corresponding to a Coulombic efficiency of only 40.5%; after 100 cycles, the electrode remains a reversible discharge capacity of 78 mA h g⁻¹ with a fading rate of only 0.09% per cycle compared with the 2^nd cycle discharge capacity. The sodium ion storage mechanism was investigated, illustrating that the large irreversible capacity loss in the first cycle can be attributed to the initially formed single-crystalline α′-Na_xV₂O₅ (0.02 < x < 0.88), in which sodium ions cannot be electrochemically extracted and the α′-Na_0.88V₂O₅ can reversibly host and release sodium ions via a single-phase (solid solution) reaction, leading to excellent cycling stability. The Na+ diffusion coefficient in α′-Na_xV₂O₅ ranges from 10⁻¹² to 10^−11.5 cm² s⁻¹ as evaluated by galvanostatic intermittent titration technique (GITT).

对电极的电化学反应过程和机理的基本了解对于开发高性能电极材料至关重要。在这项研究中，我们报告了斜方晶V ₂ O ₅单晶纳米线在1.0–4.0 V（vs。Na / Na ⁺）的电压窗口中的钠离子存储行为和机理。单晶纳米线在第一个放电/充电循环中表现出很大的不可逆容量损失，然后在随后的循环中表现出优异的循环稳定性。在100 mA g ^-1的电流密度下，纳米线电极的初始放电/充电容量为217/88 mA hg ^-1，对应的库仑效率仅为40.5％；在100次循环后，电极的可逆放电容量为78 mA hg ^-1，与^第二次循环放电容量相比，每个循环的衰落率仅为0.09％。钠离子存储机制进行了研究，示出了在第一次循环的不可逆容量大损耗可以归因于初始形成的单晶α'钠_X V ₂ ø ₅（0.02 < X <0.88），其中钠离子不能被电化学萃取，α'-的Na _0.88 V ₂ ø ₅能够可逆主机和释放钠离子通过单相（固溶体）反应，导致出色的循环稳定性。在α'-钠Na +的扩散系数_X V ₂ ø ₅范围为10 ^-12至10 ^-11.5厘米^2个小号^-1通过恒电流间歇滴定技术（GITT）作为评价。