Mapping polaronic states and lithiation gradients in individual V2O5 nanowires

Abstract

The rapid insertion and extraction of Li ions from a cathode material is imperative for the functioning of a Li-ion battery. In many cathode materials such as LiCoO2, lithiation proceeds through solid-solution formation, whereas in other materials such as LiFePO4 lithiation/delithiation is accompanied by a phase transition between Li-rich and Li-poor phases. We demonstrate using scanning transmission X-ray microscopy (STXM) that in individual nanowires of layered V2O5, lithiation gradients observed on Li-ion intercalation arise from electron localization and local structural polarization. Electrons localized on the V2O5 framework couple to local structural distortions, giving rise to small polarons that serves as a bottleneck for further Li-ion insertion. The stabilization of this polaron impedes equilibration of charge density across the nanowire and gives rise to distinctive domains. The enhancement in charge/discharge rates for this material on nanostructuring can be attributed to circumventing challenges with charge transport from polaron formation.

Localized Electrons Enhanced Ion Transport for Ultrafast Electrochemical Energy Storage

“…[ 7,8 ] Different from the conventional mechanism, it was reported that during the charging or discharging step, the ion transport can be strongly affected by the coupled interaction between the ions and movable electrons from exteriorly injecting. [ 14,15 ] Nowadays, however, there is still little study on how highly localized electrons inside the materials affect the ion transport. Such electrons can be introduced in defective materials instead of exteriorly injecting, [ 16–19 ] such as the localized excess electrons at Ti atoms near the oxygen vacancy in TiO 2 .…”

“…Some works reported that the movable electrons injected from the external circuit can strongly affect the transport of ions. [ 14,15 ] Referring to these works, the localized electrons near the oxygen vacancy should also affect the ion transport. Here, the migration barriers of Li + in different configurations are investigated to reveal the effects of how localized electrons affect the transport of Li + .…”

Structure‐Induced Switching of the Band Gap, Charge Order, and Correlation Strength in Ternary Vanadium Oxide Bronzes

“…Ternary vanadium oxide bronzes exhibit many unique structural and electronic properties . Their layered and tunnel structures facilitate the intercalation of a variety of cations, making them candidates for the next generation of Li‐ and multivalent‐ion battery cathodes .…”

“…Te rnary vanadium oxide bronzes exhibit many unique structural and electronic properties. [1][2][3] Their layered and tunnel structures facilitatet he intercalation of av ariety of cations, making them candidates for the next generation of Li-and multivalent-ion battery cathodes. [2,4,[5][6][7][8][9][10] At the same time, this can lead to the creation of many unique V 2 O 5 bronzes (M x V 2 O 5 , M = Ca, Sr,K ,P b.…”

Recent Advances in Nanostructured Vanadium Oxides and Composites for Energy Conversion

“…In general, low valence vanadium oxide nanowires could be firstly prepared via hydrothermal method and then convert to V 2 O 5 nanowires by calcination. [74] Avoiding multiple steps during the synthesis, centimeter-long [75] The oxidation state of V 2 O 5 has been maintained during the recrystallization process, and no further heat-treatment is required. However, lowered recrystallization temperature may lead to poorly crystallized V 2 O 5 .…”