On the Durability of Protective Titania Coatings on High‐Voltage Spinel Cathodes

Abstract

TiO 2 -coating of LiNi 0.5-x Mn 1.5 + x O 4 (LNMO) by atomic layer deposition (ALD) has been studied as a strategy to stabilize the cathode/electrolyte interface and mitigate transition metal (TM) ion dissolution. The TiO 2 coatings were found to be uniform, with thicknesses estimated to 0.2, 0.3, and 0.6 nm for the LNMO powders exposed to 5, 10, and 20 ALD cycles, respectively. While electrochemical characterization in half-cells revealed little to no improvement in the capacity retention neither at 20 nor at 50 °C, improved capacity retention and coulombic efficiencies were demonstrated for the TiO 2 -coated LNMO in LNMO j j graphite full-cells at 20 °C. This improvement in cycling stability could partly be attributed to thinner cathode electrolyte interphase on the TiO 2 -coated samples. Additionally, energy-dispersive X-ray spectroscopy revealed a thinner solid electrolyte interphase on the graphite electrode cycled against TiO 2 -coated LNMO, indicating retardation of TM dissolution by the TiO 2 -coating.

Controlling Cell Components to Design High‐Voltage All‐Solid‐State Lithium‐Ion Batteries

“…The shaping of CEI, surface reconstruction, and electrode protection have been done using thin titania coating on LMNO. [24][25][26] Østli et al [27] used the Atomic layer deposition (ALD) technique to coat TiO 2 of less than 1 nm thick using 20 ALD cycles to cycle LMNO to 4.9 V. The polarization and excellent reversibility of the cell was in accordance with the absence of the LiF peak in the after-cycle electrodes (Figure 2a). However, with the use of organic electrolytes along with the titaniacoated positive electrode, the coating can't provide safety from F À attack for longer cycles.…”

“…Østli et al [27] . used the Atomic layer deposition (ALD) technique to coat TiO 2 of less than 1 nm thick using 20 ALD cycles to cycle LMNO to 4.9 V. The polarization and excellent reversibility of the cell was in accordance with the absence of the LiF peak in the after‐cycle electrodes (Figure 2a).…”

“…High‐potential (>4.7 V) charging also promotes oxidation reaction of the electrolytes since common carbonate‐based solvents are unstable at such high potential [82] . Many studies have dedicated themselves to preventing the detrimental side reactions by means of coating, electrolyte engineering, and doping LNMO to alter its crystal structure [27,83] …”

“…[82] Many studies have dedicated themselves to preventing the detrimental side reactions by means of coating, electrolyte engineering, and doping LNMO to alter its crystal structure. [27,83] In this review, we aim to focus on the interfaces between solid-state electrolytes (SSEs) and LNMO. Indeed, the mentioned methods would help stabilize the SSE j LNMO interface.…”

Atomic Layer Deposition Titanium Oxide Coating for C-Rate Improvement of Li-Ion Cathodes

“…For these reasons, a titanium oxide coating was chosen as the study object. 4 In particular, some scientific groups work with titanium oxide thin films [10][11][12][13][14][15][16][17][18] and complex films, which include titanium, 17,19 on cathode surfaces, but the presented works do not consider the temperature factor of applied coating, as well as its effect on the electrochemical characteristics of modified cathodes. Only the C.-T. Hsieh's and I. Bloom groups synthesized the titanium oxide coatings on the cathode surfaces at three (120, 150, and 180 °C) and two (100 and 150 °C) different temperatures, respectively, but did not describe the causes of the achieved effect and did not focus on it.…”