Dual interface engineering of NiO/NiCo2O4/CoO heterojunction within graphene networks for high-performance lithium storage

Selenium-enriched hollow NiCo2O4/NiO heterostructured nanocages as an efficient electrocatalyst for oxygen evolution reaction

Finding clean, sustainable, and environmentally friendly technologies is especially crucial in addressing both energy and environmental challenges. To accelerate the oxygen evolution reaction (OER) and to overcome the obstacle of high energy consumption, exploring high-performance electrocatalysts is imperative to maximize the practical applicability of water splitting. Developing electrocatalyst through strategic surface modifications represents a significant approach for the construction of active catalytic centers. In the present work, we successfully synthesized selenium-incorporated hollow NiCo2O4/NiO heterostructured nanocages as electrocatalysts for the OER by precisely controlling the structure and composition of the material. The findings demonstrated that the surface-reconstructed hollow 5 wt% Se-NiCo2O4/NiO heterostructured nanocages resulted in an increased number of active sites through interfacial engineering. Benefiting from the structural control, mass transport was further expedited and due to increased conductivity, accelerated the charge transfer processes within the system. The electrocatalyst exhibited remarkable activity for the OER and displayed a low overpotential (η = 288 mV) at a current density (j) of 10 mA cm-2, small Tafel slope (66.7 mV dec-1) and better stability. This work offers a viable and adaptable method for fabricating a range of functional coordinated MOF compounds that are capable of utilization across diverse energy applications, including storage, conversion and environmental purposes.

Computational Investigation of LiF Formation at Graphite-Electrolyte Interfaces

The performance of rechargeable batteries is strongly influenced by the solid-electrolyte interphase (SEI), and a comprehensive understanding of SEI formation from the atomic level is crucial for effective battery design. The dynamics of the electrode-electrolyte interface is important and needs to be considered when evaluating the mechanism of the SEI formation. Here, we employed ab initio molecular dynamics (AIMD) and density functional theory (DFT) calculations to examine interfacial behaviors and LiF formation. Through molecular dynamics and structure sampling, we successfully constructed an electrochemical stability diagram correlating the thermodynamic free energy with the potential, which is determined by the work function of electrode surfaces. DFT calculations revealed that LiF formation at the graphite-electrolyte interfaces occurs easily via the intermediate LiHF complex. Interestingly, LiF tends to be solvated by solvents rather than directly deposited onto electrode surfaces (e.g., the Au electrode), a phenomenon we identify as a critical determinant of the porous and uneven nature of the LiF layer observed on graphite electrodes. Our finding offers new mechanistic insights into LiF formation at graphite-electrolyte interfaces.

Porous Co3O4/NiO@C Chains Assembled from Nanosheets with Excellent Lithium Storage Performance

Carbon layers-coated porous Co3O4/NiO (denoted as PCNO@C) chains are synthesized by the facile solvothermal method and subsequently annealing treatment under an Ar atmosphere, which are assembled from numerous Co3O4/NiO nanosheets. Benefiting from the unique porous chain structure, the volume change of the electrode is greatly relieved during the long-term cycling processes, and then an excellent cycling stability is obtained (the reversible specific capacity of the 1000th cycle can reach 637.3 mA h g-1 at 5000 mA g-1). Besides, a continuous conductive network is constructed by the coated carbon layers and long chains, the movement rate of electrons is effectively accelerated, and the high rate capability is obtained (the high reversible specific capacity of 480.6 mA h g-1 is retained at 10,000 mA g-1). This work contributes a new idea to construct porous chain structure anode materials.

Recent Advances on Heterojunction-Type Anode Materials for Lithium-/Sodium-Ion Batteries

Rechargeable batteries are key in the field of electrochemical energy storage, and the development of advanced electrode materials is essential to meet the increasing demand of electrochemical energy storage devices with higher density of energy and power. Anode materials are the key components of batteries. However, the anode materials still suffer from several challenges such as low rate capability and poor cycling stability, limiting the development of high-energy and high-power batteries. In recent years, heterojunctions have received increasing attention from researchers as an emerging material, because the constructed heterostructures can significantly improve the rate capability and cycling stability of the materials. Although many research progress has been made in this field, it still lacks review articles that summarize this field in detail. Herein, this review presents the recent research progress of heterojunction-type anode materials, focusing on the application of various types of heterojunctions in lithium/sodium-ion batteries. Finally, the heterojunctions introduced in this review are summarized, and their future development is anticipated.