Sodium-ion batteries have the potential to be an alternative to lithium-ion batteries especially for applications such as large-scale grid energy storage. The development of suitable cathode materials is crucial to th...Sodium-ion batteries have the potential to be an alternative to lithium-ion batteries especially for applications such as large-scale grid energy storage. The development of suitable cathode materials is crucial to the commercialization of sodium-ion batteries.Sodium-based layered-type transition metal oxides are promising candidates as cathode materials as they offer decent energy density and are easy to be synthesized. Unfortunately, most layered oxides suffer from poor air-stability, which greatly increases the cost of manufacturing and handling. The air-sensitivity severely limits the development and commercial application of sodium-ion batteries. A review that summarizes the latest understanding and solutions of air-sensitivity is desired. In this review,the background and fundamentals of sodium-based layered-type cathode materials are presented, followed by a discussion on the latest research on air-sensitivity of these materials. The mechanism is complex and involves multiple chemical and physical reactions. Various strategies are shown to alleviate some of the corresponding problems and promote the feasible application of sodium-ion batteries, followed by an outlook on current and future research directions of air-stable cathode materials. It is believed that this review will provide insights for researchers to develop practically relevant materials for sodium-ion batteries.展开更多
Molybdenum ditelluride(MoTe_(2))has recently emerged as a quantum material platform,especially exhibiting the fractional quantum anomalous Hall(FQAH)effect and unconventional superconductivity in its twisted bilayer c...Molybdenum ditelluride(MoTe_(2))has recently emerged as a quantum material platform,especially exhibiting the fractional quantum anomalous Hall(FQAH)effect and unconventional superconductivity in its twisted bilayer configuration.However,a deep understanding of the strong many-body correlations and superconductivity in this system requires systematic real-space studies of the electronic and structural properties of few-layer MoTe_(2)by scanning tunneling microscopy(STM).This remains challenging due to the high air-sensitivity of MoTe_(2)and the difficulties associated with STM device fabrication.Here,we adopted an encapsulation strategy employing monolayer hexagonal boron nitride(hBN)that enabled atomic-scale characterization of air-sensitive MoTe_(2)devices via scanning probe techniques.This approach allowed us to probe both natural and twisted bilayer MoTe_(2)(tMoTe_(2))(with twist angleθ=2.35◦)directly while preserving their intrinsic electronic states.Our high-resolution scanning tunneling spectroscopy(STS)measurements detected the extremely weak valence band at the K-valley,in agreement with large-scale density functional theory(DFT)calculations.This work not only establishes a framework for studying air-sensitive quantum materials but also provides fundamental insights into moiré-engineered correlated and topological states in van der Waals heterostructures.展开更多
基金supported by the National Natural Science Foundation of China (22179021)the Basic Science Center Project of National Natural Science Foundation of China (51788104)+1 种基金the Natural Science Foundation of Fujian Province (2019J01284)21C Innovation Laboratory Contemporary Amperex Technology Ltd (21C-OP-202011)。
文摘Sodium-ion batteries have the potential to be an alternative to lithium-ion batteries especially for applications such as large-scale grid energy storage. The development of suitable cathode materials is crucial to the commercialization of sodium-ion batteries.Sodium-based layered-type transition metal oxides are promising candidates as cathode materials as they offer decent energy density and are easy to be synthesized. Unfortunately, most layered oxides suffer from poor air-stability, which greatly increases the cost of manufacturing and handling. The air-sensitivity severely limits the development and commercial application of sodium-ion batteries. A review that summarizes the latest understanding and solutions of air-sensitivity is desired. In this review,the background and fundamentals of sodium-based layered-type cathode materials are presented, followed by a discussion on the latest research on air-sensitivity of these materials. The mechanism is complex and involves multiple chemical and physical reactions. Various strategies are shown to alleviate some of the corresponding problems and promote the feasible application of sodium-ion batteries, followed by an outlook on current and future research directions of air-stable cathode materials. It is believed that this review will provide insights for researchers to develop practically relevant materials for sodium-ion batteries.
基金supported by the National Key R&D Program of China(Nos.2022YFA1405400,2022YFA1402401,2022YFA1402404,2021YFA1401400,2022YFA1402702,2021YFA1400100,2020YFA0309000,2024YFF0727103)the National Natural Science Foundation of China(Nos.22325203,12350403,12174249,12174250,12141404,92265102,12374045,92365302,92265105,92065201,12074247,12174252,22272050,21925201,12304230)+5 种基金the Innovation Program for Quantum Science and Technology(Nos.2021ZD0302600 and 2021ZD0302500)the Natural Science Foundation of Shanghai(No.22ZR1430900)S.W.,T.L.and X.L.acknowledge the Shanghai Jiao Tong University 2030 Initiative Program.X.L.acknowledges the Pujiang Talent Program 22PJ1406700T.L.acknowledges the Yangyang Development Fund.Y.Z.acknowledges support from AI-Tennessee and Max Planck partner lab grant on quantum materials.C.L.acknowledges China Postdoctoral Science Foundation(No.GZB20230422)N.M.acknowledges the support from the Alexander von Humboldt Foundation.K.W.and T.T.acknowledge support from the JSPS KAKENHI(Nos.21H05233 and 23H02052)World Premier International Research Center Initiative(WPI),MEXT,Japan.
文摘Molybdenum ditelluride(MoTe_(2))has recently emerged as a quantum material platform,especially exhibiting the fractional quantum anomalous Hall(FQAH)effect and unconventional superconductivity in its twisted bilayer configuration.However,a deep understanding of the strong many-body correlations and superconductivity in this system requires systematic real-space studies of the electronic and structural properties of few-layer MoTe_(2)by scanning tunneling microscopy(STM).This remains challenging due to the high air-sensitivity of MoTe_(2)and the difficulties associated with STM device fabrication.Here,we adopted an encapsulation strategy employing monolayer hexagonal boron nitride(hBN)that enabled atomic-scale characterization of air-sensitive MoTe_(2)devices via scanning probe techniques.This approach allowed us to probe both natural and twisted bilayer MoTe_(2)(tMoTe_(2))(with twist angleθ=2.35◦)directly while preserving their intrinsic electronic states.Our high-resolution scanning tunneling spectroscopy(STS)measurements detected the extremely weak valence band at the K-valley,in agreement with large-scale density functional theory(DFT)calculations.This work not only establishes a framework for studying air-sensitive quantum materials but also provides fundamental insights into moiré-engineered correlated and topological states in van der Waals heterostructures.
