Bridging multiscale interfaces for developing ionically conductive high-voltage iron sulfate-containing sodium-based battery positive electrodes

Abstract

Non-aqueous sodium-ion batteries (SiBs) are a viable electrochemical energy storage system for grid storage. However, the practical development of SiBs is hindered mainly by the sluggish kinetics and interfacial instability of positive-electrode active materials, such as polyanion-type iron-based sulfates, at high voltage. Here, to circumvent these issues, we proposed the multiscale interface engineering of Na2.26Fe1.87(SO4)3, where bulk heterostructure and exposed crystal plane were tuned to improve the Na-ion storage performance. Physicochemical characterizations and theoretical calculations suggested that the heterostructure of Na6Fe(SO4)4 phase facilitated ionic kinetics by densifying Na-ion migration channels and lowering energy barriers. The (11-2) plane of Na2.26Fe1.87(SO4)3 promoted the adsorption of the electrolyte solution ClO4− anions and fluoroethylene carbonate molecules, which formed an inorganic-rich Na-ion conductive interphase at the positive electrode. When tested in combination with a presodiated FeS/carbon-based negative electrode in laboratory- scale single-layer pouch cell configuration, the Na2.26Fe1.87(SO4)3-based positive electrode enables an initial discharge capacity of about 83.9 mAh g−1, an average cell discharge voltage of 2.35 V and a specific capacity retention of around 97% after 40 cycles at 24 mA g−1 and 25 °C.

A Fast Na‐Ion Conduction Polymer Electrolyte via Triangular Synergy Strategy for Quasi‐Solid‐State Batteries

“…As shown in Figure 2a and Supplementary Figure S4, FNCPE exhibited an improved oxidative stability to 4.5 V (vs. Na/Na + ), making it suitable for application in most high-voltage cathode materials. [13] The electrochemical impedance spectroscopy (EIS) measurement reveals a much higher ionic conductivity (σ) of 1.37 mS cm À 1 for FNCPE than the 0.79 mS cm À 1 for PE at 25 °C (Figure 2b, Supplementary Figure S5 and equation S1). Based on the Arrhenius formula (Supplementary equation S2), the activation energy (E a ) of FNCPE was determined as 0.124 eV, which is lower than PE (0.260 eV, Figure 2c and Supplementary Figure S6).…”

A Fast Na‐Ion Conduction Polymer Electrolyte via Triangular Synergy Strategy for Quasi‐Solid‐State Batteries

“…Electrochemical characterizations and molecular dynamics (MD) simulations were employed to determine the ion transport property of the quasi‐solid‐state polymer electrolyte. As shown in Figure 2a and Supplementary Figure S4, FNCPE exhibited an improved oxidative stability to 4.5 V (vs. Na/Na + ), making it suitable for application in most high‐voltage cathode materials [13] . The electrochemical impedance spectroscopy (EIS) measurement reveals a much higher ionic conductivity (σ) of 1.37 mS cm −1 for FNCPE than the 0.79 mS cm −1 for PE at 25 °C (Figure 2b, Supplementary Figure S5 and equation S1).…”

Research prospects of graphene-based catalyst for seawater electrolysis

“…Usually, this structure is composed of two or more catalyst materials, which is connected together by physical or chemical bonds [97], Most graphene composites are generally connected by Van der Waals forces [98,99], including core-shell structure, although material stacking can lead to a significant increase in HER activity, and the use of electronic coupling when 2D materials are stacked with metal surfaces greatly reduces the contact resistance, thereby improving the electron transfer from metal surfaces to Van der Waals catalysis planar [99], but totally it is generally poor in terms of tunability, stability and corrosion resistance. More recently, heterostructures linked by covalent bonds whose vertical covalent linkages allow control of interlayer distances and their chemical properties will facilitate communication between 2D materials, while longer, sufficiently rigid and insulating molecules will have to help decouple materials; on the other hand, the additional leverage brought by the molecular interface will improve the intrinsic properties of the material [100][101][102], therefore, we believe that the heterostructure composed of graphene materials will have great application potential in catalyzing seawater.…”