The interfacial properties of electrode materials have a crucial impact on enhancing their charge transfer. However, a deep understanding of this aspect remains elusive. Herein, we provide an effective strategy to manipulate the internal electric field (E-field) of metal sulfide heterostructures to accelerate their Na-ion storage kinetics. To prove this concept, we selected ZnS and Fe₉S₁₀ with a large energy bandgap difference as model components with the aim to build a strong E-field at their hetero-interfaces, thus fabricating stable ZnS/Fe₉S₁₀ heterostructures for high-rate and high-capacity sodium ion storage. The emerging built-in E-field in the carbon-coated ZnS/Fe₉S₁₀ heterostructures can accelerate ion/electron migration rates and facilitate charge transfer behavior by the internal driving force of the E-field, guaranteeing enhanced reaction reversibility and sodium storage kinetics. These engineered heterostructures deliver a high initial coulombic efficiency of 85.3%, a high reversible capacity of 636 mA h g⁻¹ at 500 mA g⁻¹ and stable cycling performance. In particular, they also exhibit superior rate capacities of 295 mA h g⁻¹ at 30 A g⁻¹ and 235 mA h g⁻¹ at 50 A g⁻¹, indicating that this battery can be fully charged within 17 s. More importantly, this design concept can be extended to construct other heterostructures, such as ZnS and Sn₂S₃.

FeCl ₃ -intercalated graphite intercalation compounds are developed as stable anodes for optimized lithium storage based on a strong chemical anchoring effect.

Efficient three-dimensional (3D) spatial charge transfer in carbon anodes is crucial for improving the storage kinetics of alkali metal ion batteries. To achieve this, regulating the sp²-hybrid carbon skeleton within 3D penetration networks is an innovative approach. In this study, delocalized CS groups decorating the sp²-hybridized carbon skeleton for a 3D penetration structure were developed. The delocalized CS could optimize the spatial π-electron conjugation and the formation of spatial sp²-hybridization between carbon layers, thereby providing superior electronic and atomic structural properties. The resulting carbon skeleton of hollow carbon spheres containing CS (C5S/HCSs) facilitated an efficient 3D charge transfer channel and exhibited fast electrochemical kinetics. Specifically, compared with the control sample in potassium-ion batteries, the C5S/HCSs anode delivers a desirable reversible capacity of 238 mA h g⁻¹ at 2.0 A g⁻¹ after 2000 cycles and a high rate capability of 158 mA h g⁻¹ at 10.0 A g⁻¹, accompanied by an order-of-magnitude greater electronic conductivity and ionic diffusion coefficient. This finding offers valuable insights into the design of 3D spatial charge transfer in the carbon skeleton for achieving fast reversible ion storage kinetics.

FeCl₃-intercalated graphite intercalation compounds (GICs) with high reversible capacity and high volumetric energy density are attractive anode material alternatives of commercial graphite. However, the rapid capacity decay, which was induced by chloride dissolution and shuttling issues, hindered their practical application. To address this problem, here, we introduce flake-like Fe₂O₃ species with inherently polar surface on the edge of FeCl₃-intercalated GICs through microwave-assisted transformation of a fraction of FeCl₃ component. Theoretical simulations and physical/electrochemical studies demonstrate that the introduced Fe₂O₃ component can afford sufficient polar active sites for chemically bonding the soluble FeCl₃ and LiCl species based on the polar—polar interaction mechanism, further inhibiting the outward diffusion of the chlorides and immobilizing them within the GIC material. In a lithium ion cell, the FeCl₃-intercalated GIC with a suitable Fe₂O₃ content shows remarkably improved cycling stability with a high reversible capacity of 1,041 mAh·g⁻¹ at a current density of 200 mA·g⁻¹. Capacity retention of 91% is achieved at a high current density of 1,000 mA·g⁻¹ over 300 cycles. This work opens up the new prospect for immobilizing chlorides by introducing inorganic species in GIC for long-cycle electrochemical batteries.