Controlling Interfacial Reduction Kinetics and Suppressing Electrochemical Oscillations in Li₄Ti₅O₁₂ Thin‐Film Anodes

Abstract

Understanding the fundamentals of surface decoration effects in phase‐separation materials, such as lithium titanate (LTO), is important for optimizing the lithium‐ion battery (LIB) performance. LTO polycrystalline thin‐film electrodes with and without doped Al–ZnO (AZO) surface coating decoration are used as ideal models to gain insights into the mechanisms involved. Operando shear force modulation spectroscopy is used to observe for the first time the nanoscale dynamics of solid‐electrolyte‐interphase (SEI) formation on the electrode surfaces, confirming that the AZO coating is electrochemically converted into a stiff, homogenous SEI layer that protects the surface from the electrolyte‐induced decomposition. This AZO layer and its resultant artificial SEI‐layer have higher Li‐ion transport rates than the unmodified surface. These layers can reduce barriers to surface nucleation and facilitate rapid redistribution of lithium‐ions during the Li4Ti5O12 ⇄ Li7Ti5O12 phase separation, significantly inhabiting the orderly collective phase‐separation behavior (electrochemical oscillation) in the LTO electrode. The suppressed voltage oscillations indicate more homogeneous local exchange current density and de/intercalation states with the decorated electrodes, thereby extending their battery efficiency and long‐term cycling stability. This work highlights the ultimate importance of surface treatment for LIB materials for determining their interfacial chemistry and phase transition during the intercalation/deintercalation.

Constructing an Al3+/Zn2+-Based Solid Electrolyte Interphase to Enable Extraordinarily Stable Al3+-Based Electrochromic Devices

“…The presence of amorphous alumina and the substitution of Zn 2+ by Al 3+ ions can account for these changes, which lead to increased lattice disorder and a decrease in the crystalline lattice constant. The findings are consistent with previous reports. , The inverse fast Fourier transform (FFT) technique, utilizing Digital Micrograph, is utilized to isolate and filter the square region corresponding to the AZO/WO 3 thin film. The high-resolution TEM (HRTEM) image reveals lattice fringes of 0.169, 0.078, 0.092, and 0.240 nm.…”

“…The findings are consistent with previous reports. 38,39 The inverse fast Fourier transform (FFT) technique, utilizing Digital Micrograph, is utilized to isolate and filter the square region corresponding to the AZO/ WO 3 thin film. The high-resolution TEM (HRTEM) image reveals lattice fringes of 0.169, 0.078, 0.092, and 0.240 nm.…”

Electrochemical oscillation during galvanostatic charging and discharging of Zr-modified Li4Ti5O12 in Li-ion batteries

“… 5 Chen et al reported that the charge/discharge oscillations of Li 4 Ti 5 O 12 electrodes were suppressed by doped Al-ZnO surface coatings decoration, which can reduce barriers to surface nucleation. 13 Lim et al revealed the memory effect as well as the electrochemical oscillation of Li 4 Ti 5 O 12 with oxygen defects on the surface. 14 And we have reported the electrochemical oscillation in an Al-doped Li 4 Ti 5 O 12 composite, that has an ultra-high Al content far beyond the saturation doping concentration to form Al 2 O 3 phase.…”

Pre-lithiated Li4+xTi5O12 (0 ≤ x ≤ 3) anodes towards building high-performance Li-ion capacitors

“…The inserted Li atoms occupy octahedral 16c sites and as a result of coulombic interaction between tetrahedral sites (mutual repulsive force between newly inserted and initially present Li + ions) cause the migration of Li + ions present in the tetrahedral 8a site to octahedral 16c sites in a two-phase separation mechanism with partial reduction of Ti 4+ to Ti 3+ ions. Thus, the material exhibits a theoretical discharge capacity of $175 mA h g −1 , which operates between the de- [20][21][22][23] The equation of the reaction can be represented as:…”

“…Thus, the material exhibits a theoretical discharge capacity of ∼175 mA h g −1 , which operates between the de-lithiated spinel state Li 4 Ti 5 O 12 and lithiated rock salt state Li 7 Ti 5 O 12 . 20–23 The equation of the reaction can be represented as:(spinel LTO)Li 4 Ti 5 O 12 + 3Li + + 3e − ↔ Li 7 Ti 5 O 12 (rock salt LTO)However, both spinel and rock salt states of LTO display very similar lattice parameters with ∼0.77% lattice shrinkage in the lithiated phase (Li 7 Ti 5 O 12 ; Fm 3̄ m ). In addition to cycling stability and safety, factors such as low-cost precursors and easy fabrication methods made LTO an attractive LIC anode.…”