Electronic structural studies on the improved thermal stability of Li(Ni0.8Co0.15Al0.05)O2 by ZrO2 coating for lithium ion batteries

Abstract

The electronic structures of bare and ZrO 2 -coated Li(Ni 0.8 Co 0.15 Al 0.05 )O 2 electrode systems were investigated using a combination of time-resolved X-ray diffraction and soft X-ray absorption spectroscopy (XAS) techniques. The ZrO 2 coating on the surface of Li(Ni 0.8 Co 0.15 Al 0.05 )O 2 was effective in elevating the onset temperature of the dissociation of charged Li 0.33 (Ni 0.8 Co 0.15 Al 0.05 )O 2 , which will enhance the safety of Li-ion cells. Soft XAS spectra of the Ni L II,III -edge in the partial electron yield mode were obtained, which showed that the enhanced electrochemical properties and thermal stability of the cathode materials by ZrO 2 coating can be attributed to the suppression of unwanted Ni oxidation state changes at the surface.

Distinct Surface and Bulk Thermal Behaviors of LiNi0.6Mn0.2Co0.2O2 Cathode Materials as a Function of State of Charge

“…These phenomena are more complex than they at first appear; phase conversion is affected not only by temperature but also time of exposure, and oxygen release is affected by sample heterogeneity, , particle size, and morphology, and also intimately connected to chemomechanical occurrences such as particle cracking . Further complicating matters are interactions with other components in the cells such as carbon and binder. − To remove the effects of the latter, for this study, we prepared chemically delithiated LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC-622) samples to isolate reactions limited to those of the active materials themselves and examined materials in several different SOCs, corresponding not only to overcharge conditions but also normal top of charge (approximately 50% delithiated). We used several characterization methods designed to probe both particle surfaces and the bulk to understand the effects of thermal treatments on these model systems, with the goal of providing further information that might be useful for designing more robust cathode materials for safer batteries.…”

NCA, NCM811, and the Route to Ni-Richer Lithium-Ion Batteries

“…Actually, coating materials can be chosen among the high-k gate dielectrics that were extensively studied two decades ago to replace SiO2 gate in MOSFETs, namely TiO2, Al2O3, Y2O3, ZrO2 (see for instance [91] and citations therein), and indeed, all of them have been considered to coat NCA. For instance, the ZrO2 coating was effective not only to improve the electrochemical properties, but also in elevating the onset temperature of the dissociation in the charged state This improvement of the thermal stability is due to the suppression of Ni oxidation state changes at the surface [92]. TiO2 coating was reported by Liu et al [93], and Al2O3 by Du et al [94].…”

Advances and Prospects of Surface Modification on Nickel‐Rich Materials for Lithium‐Ion Batteries†

“…As mentioned before, the coating materials used in Ni‐rich materials include inorganics, organics, and some composite coating materials. For inorganics, the coating materials in recent works mainly include metal oxides (ZnO, [ 33 ] TiO 2 , [ 33‐37 ] Al 2 O 3 , [ 30,33,38‐42 ] ZrO 2 , [ 38,43‐46 ] Nb 2 O 3 , [ 47 ] Co 3 O 4 , [ 33,48 ] Cr 8 O 21 , [ 49 ] MgO, [ 38 ] MnO 2 , [ 50,51 ] V 2 O 3 , [ 33 ] and V 2 O 5 [ 52 ] ), metal fluorides (LiF, [ 53‐55 ] AlF 3 , [ 54,56 ] and FeF 3 [ 57 ] ), metal phosphates (LaPO 4 , [ 58‐60 ] FePO 4 , [ 61‐63 ] CoPO 4 , [ 62,63 ] AlPO 4 , [ 40,62,64‐65 ] and MnPO 4 [ 63,66 ] ), and some kinds of lithium compounds (LiBO 2 , [ 67 ] LiAlO 2 , [ 40,41,68‐71 ] Li 2 MoO 4 , [ 72 ] Li 2 ZrO 3 , [ 43,73‐74 ] Li 3 VO 4 , [ 75‐76 ] Li 3 PO 4 , [ 77‐78 ] Li 2 SiO 3 , [ 79‐81 ] Li 4 SiO 4 , [ 82 ] Li x Ti 2 O 4 , [ 70 ] Li 4 Ti 5 O 12 , [ 83‐84 ] LiZr 2 (PO 4 ) 3 , [ 85 ] and LiAlF 4 [ 54 ] ) and carbon materials (traditional carbon materials, [ 86‐88 ] modified carbon materials, [ 89‐90 ] carbon nanotube materials, […”