Ni-rich LiNi 1– x–yMn xCoyO 2 (NMC) materials are attractive as cathodes for Li-ion batteries due to their high energy density and low Co content. This study is favorable for designing high-performance NMC cathodes. This study revealed that the beneficial effects of the Al 2O 3 ALD coatings are multiple: (i) serving as an artificial layer of solid electrolyte interphase to mitigate undesirable interfacial reactions (ii) acting as a physical barrier to inhibit metal dissolution of NMC and (iii) forming a reinforced networked overcoating to boost the mechanical integrity of NMC cathodes. To this end, we utilized a suite of characterization tools and performed a series of electrochemical tests to clarify the effects of the ALD Al 2O 3 coatings. Furthermore, the ALD coatings can significantly improve the rate capability of NMC622. Particularly, the beneficial effects of the ALD Al 2O 3 coatings are more remarkable at higher upper cutoff voltages (4.5 and 4.7 V). It was found that, under different upper cutoff voltages (4.3, 4.5, and 4.7 V), the ALD Al 2O 3 coatings enable enhanced performance of NMC622 cathodes with better cyclability and higher capacity. To improve the interfacial and structural stability of NMC cathodes, herein we deposited an ultrathin layer of Al 2O 3 coatings (<5 nm) more » conformally over NMC622 composite electrodes directly using atomic layer deposition (ALD). The performance degradation typically is exhibited as capacity fading and voltage drop, mainly originating from an instable interface between the NMC622 and electrolyte as well as the evolution of the NMC structure. However, it still suffers from some evident performance degradation, especially under high cutoff voltages (i.e., >4.3 V versus Li/Li +). Vehicle Technologies Office OSTI Identifier: 1889160 Report Number(s): BNL-223469-2022-JAAM Journal ID: ISSN 2095-4956 Grant/Contract Number: SC0012704 OIA-1457888 AC02-06CH11357 Resource Type: Journal Article: Accepted Manuscript Journal Name: Journal of Energy Chemistry Additional Journal Information: Journal Volume: 69 Journal ID: ISSN 2095-4956 Publisher: Elsevier Country of Publication: United States Language: English Subject: 36 MATERIALS SCIENCE Nickel-rich cathodes Atomic layer deposition Lithium sulfide Microcracking Phase transition Interfacial = ,Īscribed to their higher capacity and lower cost compared to conventional LiCoO 2, the Ni-rich layered LiNi 0.6Mn 0.2Co 0.2O 2 (NMC622) is now considered as one promising cathode for lithium-ion batteries (LIBs). (BNL), Upton, NY (United States) Sponsoring Org.: USDOE Office of Science (SC), Basic Energy Sciences (BES) National Science Foundation Grant (NSF) USDOE Office of Energy Efficiency and Renewable Energy (EERE), Transportation Office. Publication Date: Research Org.: Brookhaven National Lab. National Synchrotron Light Source II (NSLS-II) Chemical Sciences and Engineering Division of Chinese Academy of Sciences, Beijing (China) Chinese Academy of Sciences (CAS), Beijing (China) Univ.of Arkansas, Fayetteville, AR (United States) Argonne National Lab. of Arkansas, Fayetteville, AR (United States) Thus, this study is significant and has demonstrated that sulfides may be an important class of coating materials to tackle the issues of NMCs and other layered cathodes in lithium batteries. In this regard, we disclosed that the Li 2S layer has reacted with the more » released O 2 from the NMC lattices, and thereby has dramatically mitigated electrolyte oxidation and electrode corrosion. Particularly, this study also has revealed that the nano-Li 2S coating has played some unique role not associated with traditional non-sulfide coatings such as oxides. Our investigation further revealed that all these beneficial effects of the ALD-deposited nano-Li 2S coating lie in the following aspects: (i) maintain the mechanical integrity of the NMC811 electrode (ii) stabilize the NMC electrode/electrolyte interface and (iii) suppress the irreversible phase transition of NMC structure. In addition, the Li 2S coating remarkably improved the rate capability of the NMC811 cathode. Here, our study revealed that the conformal nano-Li 2S coating shows exceptional protection over the NMC811 cathodes, accounting for the dramatically boosted capacity retention from ~11.6% to ~71% and the evidently mitigated voltage reduction from 0.39 to 0.18 V after 500 charge–discharge cycles. Different from the coatings reported in literature to date, in this work, we for the first time report a sulfide coating, amorphous Li 2S via atomic layer deposition (ALD). To address these issues, surface modification has been well-recognized as an effective strategy. The commercialization of nickel-rich LiNi 0.8Mn 0.1Co 0.1O 2 (NMC811) has been hindered by its continuous loss of practical capacity and reduction in average working voltage.
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