Constructing hierarchical structures with heterointerfaces is an effective approach for developing high‐efficiency energy‐storage anodes for sodium‐ion batteries. In this study, MoS2@ZnIn2S4 nanorods are designed and fabricated for structural improvement. Theoretical calculations reveal that there are two different MoS2‐ZnIn2S4 heterointerfaces formed by MoS2 with the Zn and In facets of ZnIn2S4, which generate directional built‐in electric fields that provide additional driving forces for facilitating electron transfer. These two heterojunction interfaces, especially the MoS2‐In facet, exhibit enhanced Na+ adsorption energies and reduce Na+ diffusion energy barriers. The multistep reactions of MoS2 and ZnIn2S4 reveal a synergistic effect that promotes the entire electrochemical process. Furthermore, the synthesized hierarchical nanorods composed of nanosheets offer abundant Na+‐storage sites and multidirectional migration pathways and, importantly, accommodate the excessive volume change. Benefiting from the heterointerfaces and hierarchical structure, the composite electrode exhibits excellent electrochemical performance, with high reaction activity and rapid electron/ion diffusion kinetics.

Enhanced Ion/Electron Migration and Sodium Storage Driven by Different MoS2‐ZnIn2S4 Heterointerfaces

As an attractive cathode candidate for sodium-ion batteries, P2-type Na2/3Ni1/3Mn2/3O2 is famous for its high stability in humid air, attractive capacity, and high operating voltage. However, the low Na+ transport kinetics, oxygen-redox reactions, and irreversible structural evolution at high-voltage areas hinder its practical application. Herein, a comprehensive study of a microbar P2-type Ni2/3Ni1/4Mg1/12Mn2/3O2 material with {010} facets is presented, which exhibits high reversibility of structural evolution and anionic redox activity, leading to outstanding rate capability and cyclability. The notable rate performance (53 mA h g-1 at 20 C, 2.0-4.3 V) contributed to the high exposure of {010} facets via controlling the growth orientation of the precursor, which is certified by density functional theory calculation and lattice structural analysis. Mg substitution strengthens the reversibility of anionic oxygen redox and structural evolution in high-voltage areas that was confirmed by the in situ X-ray diffraction and ex situ X-ray photoelectron spectroscopy tests, leading to outstanding cyclic reversibility (68.9% after 1000 cycles at 5 C) and slowing down the voltage fading. This work provides new insights into constructing electrochemically active planes combined with heteroatom substitution to improve the Na+ transport kinetics and structural stability of layered oxide cathodes for sodium storage.

Heteroatom-Substituted P2-Na2/3Ni1/4Mg1/12Mn2/3O2 Cathode with {010} Exposing Facets Boost Anionic Activity and High-Rate Performance for Na-Ion Batteries.

The development of sodium ion batteries (NIBs) can provide an alternative to lithium ion batteries (LIBs) for sustainable, low-cost energy storage. However, due to the larger size and higher m/e ratio of the sodium ion compared to lithium, sodiation reactions of candidate electrodes are expected to differ in significant ways from the corresponding lithium ones. In this work, we investigated the sodiation mechanism of a typical transition metal-oxide, NiO, through a set of correlated techniques, including electro- chemical and synchrotron studies, real-time electron microscopy observation, and ab initio molecular dynamics (MD) simulations. We found that a crystalline Na2O reaction layer that was formed at the beginning of sodiation plays an important role in blocking the further transport of sodium ions. In addition, sodiation in NiO exhibits a "shrinking-core" mode that results from a layer-by-layer reaction, as identified by ab initio MD simulations. For lithiation, however, the formation of Li antisite defects significantly distorts the local NiO lattice that facilitates Li insertion, thus enhancing the overall reaction rate. These observations delineate the mechanistic difference between sodiation and lithiation in metal-oxide conversion materials. More importantly, our findings identify the importance of understanding the role of reaction layers on the functioning of electrodes and thus provide critical insights into further optimizing NIB materials through surface engineering.

Sodiation Kinetics of Metal Oxide Conversion Electrodes: A Comparative Study with Lithiation

Anatase TiO2 is a promising anode material for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) due to its high specific capacity, low cost, and excellent cycle stability. However, low electrical conductivity and poor Na+ ion transport in TiO2 limit its practical applications. Here, substantially boosted Na+ ion transport and charge transfer kinetics are demonstrated by constructing a near-ideal non-rectifying titanium carbonitride/nitrogen-doped TiO2 (TiCx N1- x /N-TiO2 ) heterostructure. Owing to the fast plasma effects and metastable hybrid phases, the TiCx N1- x is epitaxially grown on TiO2 . Energy band engineering at the interface induces high electron densities and a strong built-in electric field, which lowers the Na+ diffusion barrier by a factor of 1.7. As a result, the TiCx N1- x /N-TiO2 electrode exhibits excellent electrochemical performance. The reversible specific capacities at rates of 0.1 and 10 C reach 312.3 and 173.7 mAh g-1 , respectively. After 600 cycles of charge and discharge at 10 C, the capacity retention rate is 98.7%. This work discovers an effective non-equilibrium plasma-enabled process to construct heterointerfaces that can enhance Na+ ion transport and provides generic guidelines for the design of heterostructures for a broader range of energy storage, separation, and other devices that rely on controlled ionic transport.

https://rss.onlinelibrary.wiley.com/doi/am-pdf/10.1002/smll.202200694

Overcoming Ion Transport Barrier by Plasma Heterointerface Engineering: Epitaxial Titanium Carbonitride on Nitrogen-Doped TiO2 for High-Performance Sodium-Ion Batteries.

Tin dioxide (SnO2) has been widely implemented as an advanced anode material for lithium or sodium ion batteries (LIBs/SIBs) owing to the high capacity and moderate potential. However, conventional synthetic...

A Robust Solvothermal-Driven Solid-to-Solid Transition Route from Micron SnC2O4 to Tartaric Acid-Capped Nano SnO2 Anchored on Graphene for Superior Lithium and Sodium Storage

Ruize Wang

Papers

Size Effects in Sodium Ion Batteries