Ni‐rich cathodes are considered feasible candidates for high‐energy‐density Li‐ion batteries (LIBs). However, the structural degradation of Ni‐rich cathodes on the micro‐ and nanoscale leads to severe capacity fading, thereby impeding their practical use in LIBs. Here, it is reported that 3‐(trimethylsilyl)‐2‐oxazolidinone (TMS‐ON) as a multifunctional additive promotes the dissociation of LiPF6, prevents the hydrolysis of ion‐paired LiPF6 (which produces undesired acidic compounds including HF), and scavenges HF in the electrolyte. Further, the presence of 0.5 wt% TMS‐ON helps maintain a stable solid–electrolyte interphase (SEI) at Ni‐rich LiNi0.7Co0.15Mn0.15O2 (NCM) cathodes, thus mitigating the irreversible phase transformation from layered to rock‐salt structures and enabling the long‐term stability of the SEI at the graphite anode with low interfacial resistance. Notably, NCM/graphite full cells with TMS‐ON, which exhibit an excellent discharge capacity retention of 80.4%, deliver a discharge capacity of 154.7 mAh g−1 after 400 cycles at 45 °C.

Atomically thin semiconducting oxide on graphene carries a unique combination of wide band gap, high charge carrier mobility, and optical transparency, which can be widely applied for optoelectronics. However, study on the epitaxial formation and properties of oxide monolayer on graphene remains unexplored due to hydrophobic graphene surface and limits of conventional bulk deposition technique. Here, we report atomic scale study of heteroepitaxial growth and relationship of a single-atom-thick ZnO layer on graphene using atomic layer deposition. We demonstrate atom-by-atom growth of zinc and oxygen at the preferential zigzag edge of a ZnO monolayer on graphene through in situ observation. We experimentally determine that the thinnest ZnO monolayer has a wide band gap (up to 4.0 eV), due to quantum confinement and graphene-like structure, and high optical transparency. This study can lead to a new class of atomically thin two-dimensional heterostructures of semiconducting oxides formed by highly controlled epitaxial growth.

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Nickel-rich layered oxides are currently considered the most practical candidates for realizing high-energy-density lithium metal batteries (LMBs) because of their relatively high capacities. However, undesired nickel-rich cathode–electrolyte interactions hinder their applicability. Here, we report a satisfactory combination of an antioxidant fluorinated ether solvent and an ionic additive that can form a stable, robust interfacial structure on the nickel-rich cathode in ether-based electrolytes. The fluorinated ether 1,1,2,2-tetrafluoroethyl-1H,1H,5H-octafluoropentyl ether (TFOFE) introduced as a cosolvent into ether-based electrolytes stabilizes the electrolytes against oxidation at the LiNi0.8Mn0.1Co0.1O2 (NCM811) cathode while simultaneously preserving the electrochemical performance of the Li metal anode. Lithium difluoro­(bisoxalato)­phosphate (LiDFBP) forms a uniform cathode–electrolyte interphase that limits the generation of microcracks inside secondary particles and undesired dissolution of transition metal ions such as nickel, cobalt, and manganese from the cathode into the electrolyte. Using TFOFE and LiDFBP in ether-based electrolytes provides an excellent capacity retention of 94.5% in a Li|NCM811 cell after 100 cycles and enables the delivery of significantly increased capacity at high charge and discharge rates by manipulating the interfaces of both electrodes. This research provides insights into advancing electrolyte technologies to resolve the interfacial instability of nickel-rich cathodes in LMBs.

Seawater batteries have attracted significant attention for use as grid-scale energy storage systems (ESSs) due to the effective utilization of abundant resources of seawater as a catholyte. Sodium ions in seawater selectively transfer through a solid electrolyte to the anode for saving the chemical energy. For the selective transfer of sodium ions, NASICON (Na3Zr2Si2PO12) electrolytes are one of the suitable candidates for the solid electrolyte to prevent a short circuit between the catholyte and anode. However, NASICON powder is known to be dissolved in water because of the structural instability, leading to catastrophic failure of the system, while NASICON solid electrolytes are stable in seawater during the battery operation. In this regard, we have carefully compared the stability of NASICON powder and pellets in both DI water and seawater associated with different degradation mechanism. Figure shows the structural stability of NASICON pellets after the immersion tests in DI water and seawater indicative of the chemical stability of NASICON in seawater. In addition, the electrochemical performance shows higher stability of the seawater-immersed electrolyte than the DI water-immersed electrolyte. The corresponding analyses are carried out to confirm the effect of the investigation. Furthermore, we have employed polymer coating methods to enhance stability and performance as a seawater battery system. The coating layer enables to prevent direct contact with seawater, resulting in longer stability during operation without compromising ionic conductivity. These results reveal that NASICON solid electrolytes can be operated in seawater with high stability and performance. Figure. The chemical stability comparison of NASICON in seawater and DI water References Mauvy, F., Siebert, E., & Fabry, P. (1999). Reactivity of NASICON with water and interpretation of the detection limit of a NASICON based Na+ion selective electrode. Talanta , 48(2), 293–303. Fuentes, R. O., Figueiredo, F., Marques, F. M. B., & Franco, J. I. (2001). Reaction of NASICON with water, Solid State Ionics , 263, 309–314. Kim, Y., Kim, H., Park, S., Seo, I., & Kim, Y. (2016). Na ion- Conducting Ceramic as Solid Electrolyte for Rechargeable Seawater Batteries. Electrochimica Acta , 191, 1–7. Jung, J. Il, Kim, D., Kim, H., Jo, Y. N., Park, J. S., & Kim, Y. (2017). Progressive Assessment on the Decomposition Reaction of Na Superionic Conducting Ceramics. ACS Applied Materials & Interfaces , 9(1), 304–310. Figure 1

In article number 2000012, Sang Kyu Kwak, Nam‐Soon Choi and co‐workers show that 3‐(trimethylsilyl)‐2‐oxazolidinone as a multifunctional electrolyte additive, promotes the dissociation of LiPF6, prevents the hydrolysis of ion‐paired LiPF6, scavenges HF in the electrolyte, and enhances the structural and compositional stability of solid–electrolyte interphase layers on Ni‐rich LiNi0.7Co0.15Mn0.15O2 cathodes and graphite anodes.