Ni-rich lithium nickel manganese cobalt oxides (LiNi x Mn y Co1–x–y O2, x ≥ 0.5, NMCs) are high-capacity cathode materials for Li-ion batteries, but they exhibit limited cycling stability under high cutoff potentials. Various aspects, including transition metal dissolution, structural disordering, particle cracking, surface film thickening, etc., have already been investigated in terms of their performance degradation in the battery research community. Interestingly, these phenomena were primarily observed at the surface layer of the cathode material, implying that they may also be facilitated by some interfacial parasitic reactions between the delithiated NMC electrode and the non-aqueous electrolyte. In this study, LiNi0.6Mn0.2Co0.2O2 (NMC 622) electrodes chemically modified with TiO2 via atomic layer deposition were used as a model system to demonstrate the criticalness of the interfacial parasitic reactions. The suppression of the interfacial parasitic reactions effectively reduced the hike of the cathodic surface film resistance, decreased the level of dissolution of transition metals, decreased the level of particle fragmentation, and mitigated the cation mixing of NMC 622. All of these results demonstrated that careful design of the interfacial layer by surface modifications is a key approach for improving the durability of Ni-rich NMCs under high-voltage cycling.

Since the discovery of graphene, there has been an ever-increasing interest in two-dimensional (2D) layered materials with exceptional properties. To this end, a variety of synthesis methods have been developed. However, it is still challenging to produce large-scale high-quality single-crystalline 2D materials. In this regard, atomic layer deposition (ALD) has recently shown great promise and has stimulated more and more research efforts, ascribed to its unique growth mechanism and distinguished capabilities to achieve nanoscale films with excellent uniformity, unrivaled conformality, and atomic-scale controllability. This review comprehensively summarizes recent progress on ALD for 2D atomic sheets, including 25 different materials and more than 80 ALD processes. This work highlights different technical routes to ALD, their precise controllability, and their underlying principles for 2D materials. It is expected that this work will help boost more research efforts for controllable growth of high-quality 2D materials via ALD.

Considering the high energy consumption during processing, and the low compliance and adhesion of ceramic electrolytes, the integration of polymer into ceramic electrolytes provides a way to mitigate the interfacial issues. However, the severe ion concentration gradient, low ionic conductivity, and instability toward Li metal and high-voltage cathodes become the major concerns in applying hybrid electrolytes. In this work, we report a single-ion-conducting hybrid electrolyte (SIE-LLZO) with 64 wt % Li7La3Zr2O12(LLZO) particles embedded in a fluoroboron-centered Li-conductive polymer framework (LiBFSIE). The SIE-LLZO electrolyte exhibited a high Li transference number of 0.94 and electrochemical stability up to 5.6 V vs Li/Li+. Promising averaged Coulombic efficiencies of 99.97% and 99.91% were achieved in cells with LiNi0.8Co0.15Al0.05O2 and LiNi0.6Mn0.2Co0.2O2 cathodes for 400 and 200 cycles, respectively. The Li-conducting pathway in the hybrid electrolyte was further investigated by a 6Li-to-7Li isotope replacement method, indicating that Li transport mainly relies on the LLZO and interface between LiBFSIE and LLZO.

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