High Redox Potential Research Articles

Rational Design of Three‐Dimensional Self‐Supporting Structure for Advanced Lithium Metal Anode

AbstractLithium metal anode (LMA) is the next generation of high‐performance electrochemical energy storage materials because of its unique advantages (high capacity and low redox potential). However, a discontinuous solid electrolyte interface (SEI) layer and lithium dendrites are formed during battery charging, leading to serious safety problems. For this purpose, researchers have devised many solutions, such as artificial SEI, modified current collector, and lithium alloy layer. Among them, the three‐dimensional (3D) current collector with a high surface area can not only reduce the local current density of lithium deposition but also promote lithium‐ion transfer and nucleation, thus inhibiting dendrite growth. In this progress report, we review the design of the LMA 3D‐structured current collector in accordance with the classification. Firstly, we discuss the latest development of advanced metal current collectors. Secondly, the 3D design of carbon‐based current collectors is summarized to improve the overall performance of lithium metal batteries (LMBs). Finally, the main challenges and development prospects of LMBs’ current collectors in the future are discussed.

Electrically conductive metal oxide-Assisted multifunctional separator for highly stable Lithium-Metal batteries

Lithium (Li) metal anodes have received intensive attention owing to its high specific capacity and low redox potential. However, chronic issues related to dendritic Li growth have hindered the pragmatic use of Li-metal batteries (LMBs). As one of feasible approaches, depositing a functional material on the separator is an efficient strategy for improving the electrochemical stability of LMBs. In this paper, we report a functionalized separator, comprising a nitrided niobium dioxide (named as n-NbO2) and a polypropylene (PP) separator. It is identified that niobium oxide interact with metallic Li, resulting in redistributing the localized Li ion. The n-NbO2-coated separator with enhanced electrical conductivity promotes Li plating/stripping process, reinforcing the Li ion redistribution effect. Due to these properties, Li-Cu cells with the n-NbO2-coated separator show the most outstanding cycle stability with high Coulombic efficiency (CE) over 200 cycles.

G-C3N4-based homojunction induced by Ag and P selective doping for improved photocatalytic H2 evolution coupled with tetracycline degradation: Type-II versus S-scheme mechanism

The reasonable design of g-C3N4(CN)-based homojunctions is a promising method to improve the photocatalytic performance. Controlling the interfacial charge-transport process is challenging. Herein, Ag and P-doped CN (ACN and PCN) were selectively synthesized. The band edges of CN move downward continuously with increasing Ag or P doping concentration. CN/4ACN (type-II), CN/8PCN (S-scheme) and 4ACN/8PCN (S-scheme) were formed by suitable energy level matching, and their charge transfer mechanisms were confirmed via VB-XPS, UPS and ESR analysis. In the presence of the hole sacrificant triethanolamine (TEOA), both CN/4ACN and 4ACN/8PCN exhibited better H2 evolution reaction (HER) rate than CN/8PCN due to the improvement in conductivity caused by Ag doping. However, only CN/8PCN and 4ACN/8PCN exhibited HER coupled with tetracycline (TC) degradation performance owing to the high redox potential of the S-scheme. Benefiting from a good carrier transport property and high redox potential, 4ACN/8PCN exhibited the best HER rate (2305.6 μmol·g−1·h−1) with TEOA as the hole sacrificant, which was 11.7 times than that of pure CN, respectively, and achieved a high HER rate (117.8 μmol·g−1·h−1) coupled with simultaneous TC degradation. This study provides a basic understanding of CN homojunctions, which shows potential for expanded applications in photocatalytic H2 evolution and pollutant degradation.

Systematic screening strategy for fungal laccase activity of endophytes from Otoba gracilipes with bioremediation potential

Fungal laccases are promising for biotechnological applications, including bioremediation and dye biotransformation, due to their high redox potential and broad substrate specificity. However, current bioprospecting methods for identifying laccase-producing fungi can be challenging and time-consuming. For early detection, it was developed a three-step, multi-criteria weighting system that evaluates fungal strains based on: First, the biotransformation capacity of three dyes (i.e., Congo red, brilliant blue G-250, and malachite green), at three different pH values, and with a relative weighting supported for the redox potential of each colorant. The relative decolorization coefficient (RDC), used as th2e first classification criterion, expressed their potential performance. Second, under the same conditions, laccase activity was estimated by observing the different degrees of oxidation of a given substrate. The selection criterion was the relative oxidation coefficient (ROC). Finally, laccase activity was quantified in submerged fermentations using three inducers (i.e., loofah sponge, Tween 80, and veratyl alcohol). This multicriteria screening strategy evaluated sixteen isolated endophytic fungal strains from Otoba gracilipes. The system identified Beltraniopsis sp. ET-17 (at pH values of 5.00 and 5.50) as a promising strain for dye biotransformation, and Phlebia floridensis as the best laccase producer, achieving a high activity of 116 μmol min−1 L−1 with loofah sponge as an inducer. In-vitro testing confirmed the efficacy of P. floridensis, with 53.61 % decolorization of a dye mixture (brilliant blue-Congo red. ratio 1:1) after 15 days of incubation. Thus, with the proposed screening strategy it was possible to highlight two species of interest at an early bioprospecting stage on a Colombian native tree poorly explored.

S-scheme heterojunction of hollow corncob-like ZnIn2S4/LaFeO3 for water splitting and tetracycline degradation

Reasonable design of heterojunction photocatalysts with high-quality interfacial coupling is an effective way to improve the photocatalytic activity of semiconductors. Herein, we successfully decorated Zinc indium sulfide (ZnIn2S4, ZIS) on perovskite Lanthanum ferrite (LaFeO3, LFO) with more active sites by a pre-hydrothermal combined post-calcination method, and constructed S-scheme heterojunction photocatalyst with a unique hollow corncob-like morphology for efficient photocatalytic hydrogen production and tetracycline (TC) degradation. When the mass ratio of LFO is 35% and 15%, the ZIS/LFO photocatalyst exhibits the best hydrogen evolution rate and TC photodegradation performance, respectively. Notably, the optimum hydrogen production rate is 6 times that of pure ZIS with excellent cycling stability. The enhanced photoactivity can be explained by the hollow corncob-like morphology and the formed S-scheme heterojunction with close interface contact between ZIS and LFO, which significantly improves the spatial separation and migration efficiency of photoexcited carriers, while maintaining a high redox potential. Finally, it provides an effective support for the photocatalytic mechanism through calculation results of density functional theory. This work not only provides a novel construction strategy of photocatalysts for efficient photocatalytic hydrogen evolution and organic pollutant degradation, but also opens up a new insight for perovskite-modified S-scheme heterojunction.

Construction of S-Scheme Co2SnO4/graphdiyne heterojunction to promote carrier transfer for efficiently photocatalytic hydrogen evolution characterized with in situ XPS

Graphdiyne (g-CnH2n-2), a novel two-dimensional carbon isomeric material consisting of a network of sp and sp2 co-hybridized hybridized carbons, has been highly regarded for its excellent chemical and physical properties and unique structure since it was first synthesized in 2010. However, as a photocatalyst, its application in the field of hydrogen production is still rare, which is a good opportunity for the field of photochemical catalyze hydrogen production. In this work, a binary catalyst Co2SnO4/graphdiyne was constructed by calcining graphdiyne and CoSn(OH)6 together after grinding. The structure of high-temperature calcination closely linked Co2SnO4 and graphdiyne, which led to an increased contact area and more active sites with faster photogenerated electron transfer efficiency. Therefore, Co2SnO4/graphdiyne showed good photocatalytic hydrogen production efficiency. Under the optimum amount of EY the hydrogen production rate reached 8.79 mmol g−1 h−1, which was 80.11 and 33.70 times higher than that of Co2SnO4 and graphdiyne, respectively. The construction of Co2SnO4/graphdiyne S-scheme heterojunction proved by in-situ XPS, EPR (DMPO-•O2−) experiment and the hydroxyl radical detection experiment retains high redox potential and prolongs the lifetime of photo-generated carriers. The catalyst preparation method in this work is innovative, which provides a general and high-efficiency strategy for applying the graphdiyne-based S-scheme heterojunction photocatalyst to solar energy-hydrogen energy conversion for photocatalytic water decomposition into hydrogen.

Achieving dendrite-free and long cyclic stability of zinc anode via CeO2 doped PEO interface modification

Aqueous zinc-ion batteries have been considered a potential substitute for lithium-ion batteries, due to its various advantages of abundant raw materials, high specific capacity and eco-friendliness. Among various anode materials, Zn metal is a promising anode of aqueous zinc-ion batteries owing to its high volumetric capacity, low cost and low redox potential. However, zinc metal anode suffers from serious problems of unrestricted dendritic growth and hydrogen production with electrolyte, resulting in capacity loss, decreased cycling performance, or even internal short circuit and battery failure. Herein, we modified zinc foil surface with CeO2-doped Polyethylene Oxide (PEO) thin film, which could effectively isolate aqueous electrolyte and zinc metal anode electrodes, and inhibit dendritic growth. In addition, theoretical calculations showed that after CeO2 doping, the band gap of the modified was reduced, which promoted the transport of Zn2+ and improved the diffusion coefficient of zinc ions. With the above synergistic effect of engineered PEO, the Zn‖Zn symmetrical cells delivered a stable cycle of 2690 h at a current of 1 mA cm−2. Moreover, this study provides technical support for the further large-scale use of aqueous zinc-ion batteries.

2D/2D Cs0.32 WO3 /CuS Nano-Heterojunctions for Simultaneous High-Efficiency Solar Desalination, Photocatalytic Decontamination, and Electricity Generation.

Desalination and power generation through solar energy harvesting is a crucial technology that can effectively address freshwater shortages and energy crises. However, owing to the complexity of the actual water environment, the thermal output capability of the photothermal material and the functional integration of the evaporation system need urgent improvement, to obtain high-quality fresh water and sufficient electricity. Herein, a 2D/2D cesium tungsten bronze/copper sulfide (2D/2D Cs0.32 WO3 /CuS) nano-heterojunction is developed and it is loaded into a cellulose-based hybrid hydrogel to construct a multifunctional evaporator. Benefiting from the more nonradiative recombination centers from deep-level defects, as well as shorter carrier migration distances and higher redox potentials in the Cs0.32 WO3 /CuS nano-heterojunction, this evaporator has a significant improvement in thermal output capacity, enabling both super-efficient seawater evaporation (4.22kg m-2 h-1 ) and photodegradation of organic pollutants (removal rate ≈ 99%). Moreover, the evaporator exhibits long-term stability and sustainable self-cleaning property against salt accumulation. Remarkably, the thermoelectric module based on the Cs0.32 WO3 /CuS nano-heterojunction shows promising electricity generation performance (4.85W m-2 ), which can power small appliances durably and stably, exceeding previously reported similar devices. This 2D/2D heterojunction-based solar evaporation system will provide a more reliable solution for efficient and sustainable freshwater-electricity co-generation in resource-limited areas.

Ion Pre-Embedding Engineering of δ-MnO2 for Chemically Self-Charging Aqueous Zinc Ions Batteries.

Aqueous zinc ion batteries (ZIBs), especially those with self-charging properties, have been promisingly developed in recent years. Yet, most inorganic materials feature high redox potential, which limit their development in the self-charging field. To achieve this target, by pre-embedding potassium ions into δ-MnO2 to reduce the energy barrier in oxygen adsorption, the first application of MnO2 in self-charging ZIBs is realized. The design features a facile two-electrode configuration with no excessively complex component to allow for energy storage and conversion. Due to the voltage difference between the oxygen in the air and the discharge products, a redox reaction can be carried out spontaneously to realize the self-charging process. After the chemical self-charging process, the Zn-K0.37 MnO2 ·0.54H2 O/C cell achieves an open circuit voltage of around 1.42V and a discharge capacity of 201mAhg-1 , reflecting the promising self-charging capability. Besides, the chemically self-charging ZIBs operate well in multiple modes of constant current charge/discharge/chemical charging. And decent cycling capability can also be achieved at extreme temperatures and high mass loading. This work promotes the development of ZIBs and further broadens the application of inorganic metal oxides in the self-charging systems.

Photo-assisted Zn-air battery promoted self-powered sensor for selective and sensitive detection of antioxidant gallic acid based on Z-scheme nanoarchitectonics with heterojunction AgBr/CuBi2O4

The development of a portable photo-assisted self-powered sensing platform with high sensitivity and selectivity for the detection of low-abundance targets is attractive. Herein, a self-powered sensor with photo-assisted zinc−air battery as a energy conversion device was developed for sensitive detection of gallic acid. The proposed photo-assisted zinc−air battery was constructed based on a AgBr/CuBi2O4 Z-scheme heterojunction with high open circuit voltage (OCV). The outstanding OCV signal benefits from the separation of electron hole pairs promoted by the Z-scheme heterojunction, which improves the photoelectric conversion efficiency. More importantly, the high redox potential of the Z-scheme heterostructure can provide sufficient driving force for photogenerated charge carriers to participate in oxygen reduction reaction, thereby realizing the co-conversion of solar and chemical energy. Furthermore, a novel signal-off detection strategy was developed based on the dual-inhibition effect of the steric hindrance and the consumption of dissolved oxygen. Notably, the chelating effect between AgBr/CuBi2O4 and the gallic acid enabled the selectivity of the as-fabricated sensor. The proposed self-powered sensor exhibits high sensitivity for detecting gallic acid and a good linearity range (1 µM ∼ 500 µM) with a low detection limit (0.87 µM), which provides a new prospective for antioxidants detection.

Kinetic modeling and cost analysis of coupled ultrasonic processes for the treatment of dairy wastewater

Sonolysis with bubble cavitation is an effective tool for the degradation of complex, recalcitrant organic compounds. Thermal and cavitation effects are additive to the breaking of complex bonds in organic contaminants by hydroxyl radicals. Strong oxidants such as persulfate (PS) and hydrogen peroxide (H2O2), with their high redox potentials (2.01 and 1.8 V, respectively), are coupled with ultrasound energy for the degradation of contaminants. PS and H2O2 generate SO4̇ and ȮH radicals, respectively with higher redox potentials (2.6 and 2.8 V, respectively). Consequently, the radicals are even more active at breaking the strong covalent bonds of the contaminants. Coupled methods in different combinations of coagulation-flocculation, chemical oxidation, and sonication are investigated for the treatment of organic content dairy wastewater. The doses of PS and H2O2 are optimized at 0.75 g/L and 25.5 g/L, respectively. The kinetic study reveals that pseudo-second-order kinetic fits experimental data with a R2 value of 0.99. The oxidation by PS and H2O2, along with ultrasound application, facilitates the removal of COD up to 84.3 % at an economically feasible treatment cost of $5.635 per kg of COD removal. Coupled process is found able to qualify dairy wastewater as dischargeable at a feasible cost of treatment.

Benzidine Derivatives: A Class of High Redox Potential Molecules for Aqueous Organic Flow Batteries.

The development of water-soluble redox-active molecules with high potentials is one of the effective ways to enhance the energy density of aqueous organic flow batteries (AOFBs). Herein, a series of promising N-substituted benzidine analogues as water-soluble catholyte candidates with controllable redox potentials (0.78-1.01 V vs. standard hydrogen electrode (SHE)) were obtained by the molecular engineering of aqueous irreversible benzidines. Theoretical calculations reveal that the redox potentials of these benzidine derivatives in acidic solution are determined by their electronic structure and alkalinity. Among these benzidine derivatives, N,N,N',N'-tetraethylbenzidine(TEB) shows both high redox potential (0.82 V vs. SHE) and good solubility (1.1 M). Pairing with H4 [Si(W3 O10 )4 ] anolyte, the cell displayed discharge capacity retention of 99.4 % per cycle and a high coulombic efficiency (CE) of ∼100 % over 1200 cycles. The stable discharge capacity of 41.8 Ah L-1 was achieved at the 1.0 M TEB catholyte with a CE of 97.2 % and energy efficiency (EE) of 91.2 %, demonstrating that N-substituted benzidines could be promising for AOFBs.

Benzidine Derivatives: A Class of High Redox Potential Molecules for Aqueous Organic Flow Batteries

AbstractThe development of water‐soluble redox‐active molecules with high potentials is one of the effective ways to enhance the energy density of aqueous organic flow batteries (AOFBs). Herein, a series of promising N‐substituted benzidine analogues as water‐soluble catholyte candidates with controllable redox potentials (0.78–1.01 V vs. standard hydrogen electrode (SHE)) were obtained by the molecular engineering of aqueous irreversible benzidines. Theoretical calculations reveal that the redox potentials of these benzidine derivatives in acidic solution are determined by their electronic structure and alkalinity. Among these benzidine derivatives, N,N,N′,N′‐tetraethylbenzidine(TEB) shows both high redox potential (0.82 V vs. SHE) and good solubility (1.1 M). Pairing with H4[Si(W3O10)4] anolyte, the cell displayed discharge capacity retention of 99.4 % per cycle and a high coulombic efficiency (CE) of ~100 % over 1200 cycles. The stable discharge capacity of 41.8 Ah L−1 was achieved at the 1.0 M TEB catholyte with a CE of 97.2 % and energy efficiency (EE) of 91.2 %, demonstrating that N‐substituted benzidines could be promising for AOFBs.

Slight Multielement Doping-Induced Structural Order-Disorder Transition for High-Performance Layered Na-Ion Oxide Cathodes.

To realize concurrently the high-energy density and excellent cycling stability, maximum utilization of redox couple, minimization of detrimental phase transition, and structural degradation of O3-type layered oxide cathodes are critical for developing Na-ion batteries. Ni2+/Ni4+ redox couple showing multielectron reaction and higher redox potential is favorable to increase the energy density. However, the Jahn-Teller distortion of Ni3+ generated upon (dis)charging results in a strong anisotropy in the local crystal structure that causes irreversible interlayer bending and chemo-mechanical cracks of the cathode particles, compromising the electrochemical properties eventually. In this work, we show a slight multielement doping strategy that enlarges the amount of active redox components while minimizing the inactive contents. The results show that the uniform distribution of multiple components can help increase the disorder degree of atom arrangement and alleviate the structural changes and detrimental anisotropy cracks. As a proof of concept, a multielement-doped O3-type Na0.9Ni0.25Cu0.05Mg0.05Zn0.05Fe0.05Al0.05Mn0.40Ti0.05Sn0.05O2 oxide is rationally prepared that presents better chemo-mechanical stability and delayed O3-P3 phase transition behavior. Compared to the high Ni-content Na0.9Ni0.35Fe0.2Mn0.45O2 cathode, this as-prepared multielement material delivers a reversible capacity of about 120 mAh/g in the voltage range of 2-4.0 V, superior cycling stability with 90% of capacity retention after 500 cycles, and excellent rate capability (more than 70% of initial capacity at 5.0 C). This work indicates that the multielement doping method is highly suitable for the development of advanced Na-ion layered oxide cathodes.

Carbon‐anchored Sb nanoparticles as high‐capacity and stable anode for aqueous alkaline batteries

AbstractAntimony (Sb) holds a high theoretic capacity and suitable redox potential as a promising anode for aqueous alkaline batteries (AABs). However, the uncontrollable nucleation for SbO2− and promiscuous water‐induced side reactions severely degrade the reversibility of Sb anode. Herein, the carbon‐anchored Sb nanoparticles are constructed to induce uniform Sb plating/stripping for high‐performance AABs. The experimental results reveal that the enhanced interaction between carbon and antimony as well as defective carbon can significantly improve the electrical conductivity and decrease the Sb nucleation overpotential. Accordingly, the as‐prepared Sb anode enables preferential plating of Sb rather than parasitic side reactions. As a result, the cycle life of A‐Sb/CF is sustained over 500 cycles at 10 mA cm−2/2 mAh cm−2. Even at the high capacity of 4 mAh cm−2, this anode can cycle stably for 225 cycles, which is significantly better than the Sb/CF counterpart. Furthermore, the assembled Ni3S2@Ni(OH)2//A‐Sb/CF full battery demonstrates a high capacity of 2.17 mAh cm−2 and a stable cycle life of over 500 cycles.

Electrocatalysis of Fe‐N‐C Bonds Driving Reliable Interphase and Fast Kinetics for Phosphorus Anode in Sodium‐Ion Batteries

AbstractPhosphorus exhibits high capacity and low redox potential, making it a promising anode material for future sodium‐ion batteries. However, its practical applications are confined by poor durability and sluggish kinetics. Herein, an innovative in‐situ electrochemically self‐driven strategy is presented to embed phosphorus nanocrystal (≈10 nm) into a Fe‐N‐C‐rich 3D carbon framework (P/Fe‐N‐C). This strategy enables rapid and high‐capacity sodium ion storage. Through a combination of experimental assistance and theoretical calculations, a novel synergistic catalytic mechanism of Fe‐N‐C is reasonably proposed. In detail, the electrochemical formation of Fe‐N‐C catalytic sites facilitates the release of fluorine in ester‐based electrolyte, inducing Na+‐conducting‐enhanced solid‐electrolyte interphase. Furthermore, it also effectively induces the dissociation energy of the P‐P bond and promotes the reaction kinetics of P anode. As a result, the unconventional P/Fe‐N‐C anode demonstrates outstanding rate‐capability (267 mAh g−1 at 100 A g−1) and cycling stability (72%, 10 000 cycles). Notably, the assembled pouch cell achieves high‐energy density of 220 Wh kg−1.

Enrichment and characterization of a nitric oxide-reducing microbial community in a continuous bioreactor

Nitric oxide (NO) is a highly reactive and climate-active molecule and a key intermediate in the microbial nitrogen cycle. Despite its role in the evolution of denitrification and aerobic respiration, high redox potential and capacity to sustain microbial growth, our understanding of NO-reducing microorganisms remains limited due to the absence of NO-reducing microbial cultures obtained directly from the environment using NO as a substrate. Here, using a continuous bioreactor and a constant supply of NO as the sole electron acceptor, we enriched and characterized a microbial community dominated by two previously unknown microorganisms that grow at nanomolar NO concentrations and survive high amounts (>6 µM) of this toxic gas, reducing it to N2 with little to non-detectable production of the greenhouse gas nitrous oxide. These results provide insight into the physiology of NO-reducing microorganisms, which have pivotal roles in the control of climate-active gases, waste removal, and evolution of nitrate and oxygen respiration.

Nanoconfining ultrafine heterostructured sulfides in carbon nanofibers enabling ultrastable and fast sodium storage

Transition metal sulfides (TMSs) are considered as promising anodes for sodium ion batteries (SIBs) due to their high theoretical specific capacity and low redox potential. Unfortunately, poor structural stability and sluggish kinetics of the sulfides result in an unsatisfactory cycling stability and rate performance. Herein, the ultrafine Co9S8/WS2@C particles embedded in carbon nanofibers (CNF) can be obtained via nanoconfinement strategy coupled with electrospinning technique, and the as-synthesized Co9S8/WS2@C@CNF realizes the achievement of superb rate performance (378.8 mA h g−1 at 2 A g−1), and stable structural stability (92.1% capacity retention after 700 cycles at 2 A g−1). Specifically, these outstanding electrochemical properties are closely related with the introduction of β-cyclodextrin (β-CD) during the synthesis process, in which the β-CD can act as the nanoreactor and the activator for confining ultrafine nanoparticles and generating porous structure. The combining of large surface area, ultrafine particles, and rich heterointerfaces in Co9S8/WS2@C@CNF can effectively reduce the Na+ diffusion length and promote reaction kinetics. The impressive electrochemical character of Co9S8/WS2@C@CNF anode is further confirmed in full-cell Na-ion batteries, which also displays ultra-long-life span (92.9% capacity retention after 500 cycles). It should be noted that the unique nanoreactor with nanoconfinement function can be adapted to the construction of other metal sulfide electrodes for building ultra-stable energy-storage devices.

Perspectives on the development of advanced lithium metal anode

The demand for high-energy Li batteries is rapidly increasing due to the growing market for electric vehicles and portable electronic devices. Lithium (Li) metal has been considered as an ideal anode for high-energy Li batteries because of its high theoretical capacity (3860 mAh g<sup>-1</sup>) and low redox potential (-3.04 V vs. SHE). However, the utilization of Li metal anode is still limited by fundamental problems associated with unavoidable dendritic growth and huge volume changes during cycling. To improve the electrochemical performance of Li metal anode, various strategies have been explored including electrolyte design, interfacial engineering, and structural modifications. One of the most promising approaches is to store Li metal in porous host materials, which can effectively suppress the formation of Li dendrite and volume expansion. Herein, we focus on recent progress in the development of advanced Li metal anodes and suggest research directions and design rules.

Computational study of Na diffusion and conduction in P2- and O3-Na2x[NixTi1-x]O2 materials with machine-learning interatomic potentials

Sodium-ion batteries (SIBs) provide a feasible solution for large-scale energy storage applications of sustainable energy resources like wind and solar energy. Layered sodium nickel titanates (Na2x[NixTi1-x]O2) (SNTL) are considered a promising electrode material for SIBs since they can function as either a positive or negative electrode due to the coexistence of high redox potential element Ni (V = 3.7 V vs. Na/Na+) and low redox potential element Ti (V = 0.7 V vs. Na/Na+). There have been both experimental and computational studies on the family of Na2x[NixTi1-x]O2 materials, investigating their structures, electrochemical performance, electronic and ionic conductivity, etc. However, the current understanding of the Na migration mechanism is still very limited at an atomic level because of the restrictions of simulation methods: density-functional theory (DFT) simulation is restricted to a small length and time scale, whereas the conventional empirical interatomic potential (IP) is restricted by a limited accuracy. To solve this efficiency-versus-accuracy dilemma, herein we developed a neural network (NN)-based machine-learning interatomic potential (MLIP), which is trained using DFT data. Our MLIP demonstrates a DFT-approaching accuracy in terms of atomic forces. Moreover, the extracted Na self-diffusivity, ionic conductivity, and activation energy values from MLIP-MD simulation agree well with experimental data. In general, P2-SNTL demonstrates a higher Na self-diffusivity and ionic conductivity than O3-SNTL, mainly due to the larger bottleneck size through which Na ions migrate. We also employed the incoherent density correlation function to study the Na migration mechanism. The Singwi-Sjölander (SS) model and Chudley-Elliot (CE) model were used to fit the jump-diffusion behavior in P2- and O3-SNTL, respectively. The obtained jump distance values match well with the typical distance between the nearest Na sites in P2- and O3-SNTL, confirming that the hopping events happen mostly between neighboring Na sites in SNTL. The decrease of residence time and jump distance values with temperature is a result of higher ion mobility and level of delocalization, as validated by the nuclear density maps. In addition, our study also confirmed that both the “straight” and “curved” Na migration paths exist in O3-SNTL, in contrast to previous studies which only mention the “curved” migration path. In the end, our calculated Haven ratios have a value <1, indicating that it is more likely for the Na hopping events to occur via a concerted migration of several atoms other than the jump of an isolated atom.