Electrochromic Corundum-like Compound Based on the Reversible (De)insertion of Lithium: Li₂Ni₂W₂O₉

Abstract

The search for efficient anodic electrochromic materials is essential to the development of electrochromic devices, such as smart windows. Magnetron-sputtered lithium-nickeltungsten mixed oxides are good candidates to tackle this issue; however, they display a complicated microstructure, making it difficult to pinpoint the origin of their electro-optical properties. Herein, by exploring the Li 2 O−NiO−WO 3 phase diagram, we obtained a new phase, Li 2 Ni 2 W 2 O 9 , that crystallizes in the orthorhombic Pbcn space group. This material can reversibly uptake/release 0.75 Li + (31 mA h•g −1 ) when cycled between 2.5 and 5.0 V versus Li + /Li. Moreover, through operando optical microscopy, we show that this new phase is electrochromic, and crucial information can be accessed about the diffusion-limited insertion of lithium at the single-particle scale. This study sets the ground for future syntheses of electrochemically active materials crystallizing in the ramsayite structure and details how the electrochromic properties of battery materials can be used to shed some light on their electrochemical mechanisms.

Recent Advance in Electrochromic Materials and Devices for Display Applications

“…[53] However, poor cycling stability and the limited difference in transmittance between bleached and colored states limit the applications. To solve these problems, Redor et al [51] undertook the synthesis of a novel phase named Li 2 Ni 2 W 2 O 9 (LNWO) via a solid-state reaction. This compound exhibits a layered structure characterized by the alternating arrangement of NiO 6 and WO 6 octahedra, and Li + is located in the interlayer gap.…”

“…Reprinted (adapted) with permission. [51] Copyright 2023 American Chemical Society. (g) Device structure.…”

“…(f) Average discharge capacity (green dots) and average coulombic efficiency (black diamonds). Reprinted (adapted) with permission [51] . Copyright 2023 American Chemical Society.…”

Deciphering the Interplay between Local and Global Dynamics of Anodic Metal Oxidation

“…RM is a label-free optical imaging technique that leverages local changes in the refractive index at the image interface to elucidate various (electro-)­chemical phase transformations. − Garcia et al ,, demonstrated that, in the context of metal oxidation, light intensities correlated ex situ with surface analysis techniques can indicate phenomena such as dealloying, subsurface corrosion, etching, or pitting in Al alloys. Recently, optical models utilizing light interference at oxidized metal interfaces have shown that variations in optical intensities can quantitatively relate to the thickness (to nanometer precision) and composition of surface films. ,,, These parameters are central to our understanding of metal passivation and corrosion protection.…”

Optics Determines the Electrochemiluminescence Signal of Bead-Based Immunoassays

“…They enable deciphering at high throughput and high spatial resolution intricate chemical mechanisms. − ECL imaging is indeed also used to decipher the coreactant pathways or reactivity of different micro-/nano-objects. ,− In particular, the (electro)­chemical mechanisms operating in bead-based ECL immunoassays have been investigated by analyzing the ECL signals. ,,,,, Mechanistic insights are most often reached by considering the modeling of the transport and chemical reactivity of the ECL reaction intermediates. However, as in other optical microscopy configurations, ,,− modeling the optical wave propagation in the objects under investigation (and the optical properties of the media used) enables further mechanistic insights. In the context of ECL, considering interference effects, for example, enabled probing the coreactant intermediate stability .…”