eV For Na Research Articles

SiP2 monolayer as potential anode material for Na/K-ion batteries predicted from first-principles calculations

Based on the density functional theory (DFT), a systematic feasibility analysis of monolayer SiP2 as potential anode material for Na/K-ion batteries has been carried out. Through ab-initio molecular dynamics (AIMD) calculation, the findings reveal exceptional stability of SiP2. The ultra-low ion diffusion barriers (0.107 eV for Na and 0.043 eV for K) and metallic properties following adsorption of alkali metal ions demonstrate that SiP2 exhibits a rapid charge and discharge rate and remarkable electrical conductivity when employed as an anode. Furthermore, it possesses a considerable theoretical storage capacity (Na/K: 446.53/595.38 mAh/g) and energy density (Na/K: 1026.91/1322.46 mWh/g). These findings suggest that monolayer SiP2 exhibits superior performance as potential anode material for Na/K-ion batteries.

Breaking new ground in metal-ion battery anodes: First principles design of Dirac nodal line semimetallic carbon materials

With the rapid development of electronic devices, the demand for batteries has gradually increased, and existing batteries can no longer satisfy it. In this paper, a three-dimensional honeycomb carbon material is designed and termed pmma-C32. The mechanical stability, dynamic stability, thermal stability, and mechanical stability were investigated through first-principles molecular dynamics, phonon spectrum, and the Born-Huangkun criterion. The calculation results show that pmma-C32 not only has good thermodynamic stability, but also has static stability. Similar to graphene, pmma-C32 exhibits semi-metallic characteristics, featuring two Dirac node lines with high Fermi velocity, indicating a high capacity for electron transport. As a metal-ion battery material, pmma-C32 exhibits higher theoretical capacity(836.8, 732.2, and 418.4 mA h/g for Li, Na, and K), lower diffusion barrier (0.06–0.12 eV for Li, 0.10–0.11 eV for Na, and 0.05–0.06 eV for K), and lower open circuit voltage (0.34 V for Li, 0.37 V for Na, and 0.74 V for K). These remarkable properties endow semimetallic pmma-C32 as a promising anode material for metal-ion batteries, providing fast charge and discharge rates. This research not only broadens the family of three-dimensional carbon materials, but also greatly improves the performance for universal metal-ion battery anode materials through material structure design.

Theoretical Investigation of a Novel Two-Dimensional Non-MXene Mo3C2 as a Prospective Anode Material for Li- and Na-Ion Batteries.

A new two-dimensional (2D) non-MXene transition metal carbide, Mo3C2, was found using the USPEX code. Comprehensive first-principles calculations show that the Mo3C2 monolayer exhibits thermal, dynamic, and mechanical stability, which can ensure excellent durability in practical applications. The optimized structures of Lix@(3×3)-Mo3C2 (x = 1-36) and Nax@(3×3)-Mo3C2 (x = 1-32) were identified as prospective anode materials. The metallic Mo3C2 sheet exhibits low diffusion barriers of 0.190 eV for Li and 0.118 eV for Na and low average open circuit voltages of 0.31-0.55 V for Li and 0.18-0.48 V for Na. When adsorbing two layers of adatoms, the theoretical energy capacities are 344 and 306 mA h g-1 for Li and Na, respectively, which are comparable to that of commercial graphite. Moreover, the Mo3C2 substrate can maintain structural integrity during the lithiation or sodiation process at high temperature. Considering these features, our proposed Mo3C2 slab is a potential candidate as an anode material for future Li- and Na-ion batteries.

Ab Initio Molecular Dynamics Investigation on the Permeation of Sodium and Chloride Ions Through Nanopores in Graphene and Hexagonal Boron Nitride Membranes.

Nanoporous membranes promise energy-efficient water desalination. Hexagonal boron nitride (h-BN), like graphene, exhibits outstanding physical and chemical properties, making it a promising candidate for water treatment. We employed Car-Parrinello molecular dynamics simulations to establish an accurate modeling of Na+ and Cl- permeation through hydrogen passivated nanopores in graphene and h-BN membranes. We demonstrate that ion separation works well for the h-BN system by imposing a barrier of 0.13 eV and 0.24 eV for Na+ and Cl- permeation, respectively. In contrast, for permeation of the graphene nanopore, the Cl- ion faces a minimum of energy of 0.68 eV in the nanopore plane and is prone toward blockade of the nanopore, while the Na+ ion experiences a slight minimum of 0.03 eV. Overall, the desalination performance of h-BN nanopores surpasses that of their graphene counterparts.

Computational exploration of high-capacity hydrogen storage in alkali metal-decorated MgB2 material

In this study, a novel substrate complex is developed by integrating alkali metals such as Li/Na/K onto magnesium diboride (MgB2). The research involves comprehensive density functional theory (DFT) to analyze the complex optimized structures, thermodynamic characteristics, and H2 storage capabilities. The results underscore a subtle charge transfer from Li/Na/K to the pristine MgB2 monolayer, augmenting its electropositive characteristics. This attribute proves particularly advantageous for H2 storage, as it enhances the electrostatic interactions between the complex and hydrogen (H2) molecules. The structure of Li/Na/K-decorated MgB2 with various numbers of attached H2 molecules is also explored. The maximum H2 adsorption is observed with nine H2 molecules for Li (n = 9H2) and eight H2 molecules for both Na and K (n = 8H2). The adsorption energies for these configurations fall within the range of −0.24 to −0.21 eV for Li, −0.22 to −0.20 eV for Na, and −0.25 to −0.20 eV for K. Notably, gravimetric capacities of 14.6 wt%, 23.37 wt%, and 18.94 wt% are attained for Li, Na, and K-decorated MgB2, respectively. These values demonstrate a significant surpassing of the U–S Department of Energy (DOE) target of 5.5 wt%. This groundbreaking material has the potential to play a crucial role in promoting efficient and sustainable solutions for H2 storage, meeting the increasing need for clean energy technologies.

Reversible multielectron redox activity of the anti-NASICON-type phosphate LiNbV(PO4)3 towards lithium and sodium intercalation.

The LiNbV(PO4)3 phosphate with the anti-NASICON structure (a = 12.126(1) Å, b = 8.6158(4) Å, c = 8.6959(6) Å, V = 908.5(1) Å3, S.G. Pbcn) has been synthesized using a Pechini sol-gel process. It exhibits reversible multielectron transitions versus Li and Na anodes. In a Li half-cell, it supports a 4e- transfer due to the activation of the Nb5+/Nb3+ and V4+/V2+ redox couples, being the first example of 4d metal redox transitions within the anti-NASICON framework confirmed by XANES measurements. X-ray diffraction performed in ex situ and operando regimes disclosed a single-phase mechanism of lithium (de)intercalation. In a Na half-cell, the material demonstrates reversible uptake of 2.77 Na+ ions. Density functional theory calculations revealed percolation barriers of ∼0.5-0.7 eV for Na+ hopping, thus supporting the activation of Na+ ion diffusion in the NbV(PO4)3 framework. This study introduces a new approach to improve anti-NASICON-structured electrode materials by utilizing redox transitions of 4d elements for energy storage.

A novel Tetrahexcarbon as a high-performance anode material for Na-ion and K-ion batteries

The search for high storage capacity anode materials has been an important topic in the field of ion batteries. With the gradual development of two-dimensional (2D) materials, their potential as high-performance electrode materials have been demonstrated. Here, using first principles calculations, we investigate the feasibility of novel Tetrahexcarbon as a high-performance anode material for Na/K ion batteries. Our results indicate that Na/K ions can be chemically and stably adsorbed on the surface of Tetrahexcarbon. It is noteworthy that the Na capacity of Tetrahexcarbon is up to 2233.3 mAh g-1 and the K capacity up to 744.4 mAh g-1 with a guaranteed low diffusion barrier (0.14 eV for Na; 0.18 eV for K). Therefore, our calculations show that Tetrahexcarbon is an excellent anode material with great potential for ultra-high energy storage devices.

Conductive BSi4 monolayer with superior electrochemical performance for alkali metal ion batteries

Silicon has received great interest in the development of next-generation metal ion batteries (MIBs) due to its extremely high capacity; however, the large volume expansion during intercalation process and intrinsically low electrical conductivity has severely hindered its electrochemical performance. In this work, we theoretically report that the recently-developed BSi4 monolayer is an appealing candidate as a flexible anode for high-performance MIBs. The BSi4 anode exhibits high mechanical and thermal stability with inherent metallicity, which is very advantageous for the fast electronic transport during battery cycle. All metal atoms are stably deposited on the anode surface with high ion mobility. The lowest diffusion barrier is predicted to be 0.33 eV for Li, 0.22 eV for Na, and 0.17 eV for K. Remarkably, the BSi4 anode possesses high Li/Na/K storage capacities of 1087.97, 1087.97 and 870.37 mA h/g, and low averaged open circuit voltages of 0.80, 0.52 and 0.63 V. Moreover, the BSi4 anode could withstand a large ultimate strain of 16.72 % (20.27 %) along zigzag (armchair) direction, showing a good mechanical flexibility.

Electrochemistry Enabled Heterostructure with High Tap Density for Ultrahigh Power Na‐Ion Capacitors

AbstractDeveloping electrode materials with high tap density, low cost, and superior performance poses a formidable challenge in electrochemistry. The impressive performance exhibited by most electrodes comes at the expense of tap density and cost, severely limiting their practical applications. Here, combining computational and experimental results, an approach for the electrode materials with high tap density and rich heterostructure (Cu2S/Na2Sn) from cheap copper smelting slag enabled by an electrochemical process is proposed, reducing the diffusion energy barrier from 0.82 to 0.28 eV for Na+, as well as delivering an impressively high tap density of 3.32 g cm−3. Furthermore, the electrochemical activation process that irreversibly generates more stable Cu2S and Na2Sn after the first charge progress of parent materials is also revealed by in/ex situ analytical techniques. As expected, assembled sodium ion capacitors (SICs) achieve high energy density (74.4 Wh kg−1) at high power density (20 000 W kg−1) with outstanding capacity retention of 81.5% after 10 000 cycles, delivering over 76% of its energy density in 13.4 s, which surpasses the performance achieved by state‐of‐the‐art SICs. This work not only provides novel insights into irreversibly conversion‐type anodes but also introduces a method for efficient value‐added utilization of smelting slag.

Defects induced metallized boron hydride monolayers as high-performance hydrogen storage architecture

Experimental synthesis of two-dimensional boron hydride monolayer (BH-ML) (J. Am. Chem. Soc. 2017, 139, 13,761) has motivated us to explore its application in clean energy storage. We have performed first-principles calculations based on spin-polarized density functional theory (DFT) to investigate the ground-state geometries, electronic structures, metal doping mechanism and hydrogen (H2) storage propensities of BH-ML. Pristine BH-ML barely binds H2, however the introduction of selected light metal dopants, such as Na, Ca, and Sc, improved the H2 adsorption mechanism tremendously. Binding energies of dopants under maximum doping concentration are found as −1.51, −2.49, and −4.54 eV for Na, Ca, and Sc, respectively, which are strong enough to ensure their uniform distribution over BH-ML without clustering. Each dopant donated bulk of its charge to BH-ML and transforms into cation and anchored multiple H2 molecules through electrostatic and van der Waals interactions. We have found that a maximum of 24H2 molecules could be adsorbed on BH-ML decorated with four metal dopants of Na, Ca, and Sc. Average adsorption energies of H2 are found within desirable range. Our results show that Na, Ca, and Sc decorated BH-ML could reach to exceptionally high H2 storage capacities of 14.84, 12.28, and 11.70%, respectively, which easily surpass the US Department of Energy (DOE) target of 5.50 wt% by 2025. We have further applied thermodynamic analysis to explain the H2 storage proficiencies at practical conditions of temperatures and pressures. Our report confirms that BH-ML decorated with light metal dopants are ideal option for high-capacity H2 storage applications.

Exploring the potential of T-Graphene-like BC2N monolayer as an anode material for Na/K-Ion batteries

We conducted a thorough analysis to assess the suitability of a T-graphene-like BC2N monolayer as an electrode material for sodium-ion batteries (NIBs) and potassium-ion batteries (KIBs) using first-principles calculations. Our investigation demonstrates the chemical adsorption of Na/K atoms onto the BC2N monolayer, which exhibits metallic properties after Na/K adsorption, ensuring excellent electrode conductivity. The average open-circuit voltages for Na and K are 0.39–0.12 V and 0.87–0.14 V, respectively. Furthermore, the BC2N monolayer revealed significantly lower Na/K diffusion barriers (0.40 eV for Na and 0.22 eV for K) and higher storage capacities (1647 mAh g−1 for Na and 2196 mAh g−1 for K) compared to conventional two-dimensional anode materials. These exceptional characteristics highlight the promising potential of the T-graphene-like BC2N monolayer in advancing Na/K-ion batteries technology.

A novel two-dimensional whorled TiB4 as a high-performance anode material for Li-ion and Na-ion batteries

The search for high storage capacity anode materials has been an important topic in the field of ion batteries. With the gradual development of two-dimensional (2D) materials, their potential as high-performance electrode materials have been demonstrated. Here, using first principles calculations, we investigate the feasibility of novel 2D TiB4 as an ideal anode material for Li/Na ion batteries. Our results indicate that Li/Na ions can be chemically and stably adsorbed on the surface of 2D TiB4. It is noteworthy that the Li capacity of 2D TiB4 is up to 2353.2 mA h g−1 and the Na capacity up to 1764.9 mA h g−1 with a guaranteed low diffusion barrier (0.24 eV for Li; 0.09 eV for Na). Therefore, our calculations show that TiB4 monolayer is an excellent anode material with great potential for ultra-high energy storage devices.

Enhancement of electrochemical performance of monolayer SnS_2 for Li/Na-ion batteries through a sulphur vacancy: a DFT study

Various transition metal dichalcogenides materials have been investigated from bulk to monolayer phases for different advanced technological applications. Tin disulfide monolayer offers advantages as an anode material for Li/Na-ion batteries, although it cannot be considered ideal for direct exploitation. We systematically performed a comparative study of the adsorption and diffusion behaviour of Li/Na on a pristine SnS_2 monolayer and on a SnS_2 monolayer with S-vacancy for enhancement of electrochemical performance, using density functional theory approach. Although all the adsorption sites are exothermic, it was established that Li/Na adatoms mostly prefer to bind strongly on SnS_2 monolayer with S-vacancy but avoiding the S-vacancy site. It was established that avoiding the S-vacancy site along the path, excellent diffusion barriers of 0.19 eV for Li and 0.13 eV for Na were achieved, suggesting possible ultrafast charge/discharge rate. Due to reduced molar mass, the SnS_2 monolayer with S-vacancy has a slightly higher storage capacity than its pristine counterparts for both Li and Na adatoms. The obtained open circuit voltage values are within the range of 0.25–3.00 V assuring that the formation of dendrites can surely be averted for the envisaged battery operation. Understanding the effects of an S-vacancy on the electrochemical properties of Li/Na on the SnS_2 monolayer allows us to consider possible improvements to energy storage devices that can be applied as a result of improved anode material.

Fast Na+ ion dynamics in the Nb5+ bearing NaSICON Na3+x−zNbzZr2−zSi2+xP1−xO12 as probed by 23Na NMR and conductivity spectroscopy

NaSICON-type (Na superionic conductor, Na1+yZr2SiyP3−yO12, 0 < y < 3) represent a class of fast Na+ ion conductors with bulk ion conductivities in the mS range near room temperature. Starting from Na3Zr2(SiO4)2(PO4), i.e., from y = 2, we investigated the change in ion transport parameter when x in Na3+xZr2Si2+xP1−xO12 is increased from 0 to 0.4 and Nb5+ is substituted for Zr4+ according to Na3+x−zNbzZr2−zSi2+xP1−xO12 (z = 0.04). The later might be beneficial also to change the transport properties in or near the grain boundary regions of our polycrystalline samples. To detect such changes, we used low-temperature conductivity and electric modulus spectroscopy to differentiate between the total and the bulk (intragrain) electrical responses. However, the main purpose of the present study is to corroborate the extraordinarily high bulk ionic conductivity of approximately 7.3 mS cm−1 (x = 0.4 and z = 0.04, room temperature) by diffusion-controlled 23Na NMR spin-lattice relaxation measurements. Indeed, such experiments directly sense the 23Na spin-fluctuations at the nuclear sites as a result of the fast intragrain motional processes. Both methods, nuclear and non-nuclear, point to a mean activation energy of 0.3 eV for Na+ exchange among the multiple sites in the NaSICON framework. In addition, NMR reveals local barriers characterized by activation energies as low as 0.1 eV. Altogether, from a dynamic point of view, Na3.36Nb0.04Zr1.96Si2.4P0.6O12 turned out to be indeed a very promising candidate for the breakneck development of Na-based all-solid-state battery applications.

Dopant-enhanced sodium and potassium-ion adsorption and diffusion in two-dimensional titanium disulfide

Two-dimensional (2D) titanium disulfide (TiS2) is the lightest transition-metal dichalcogenide (TMD). It exhibits relatively better adsorption and diffusion of sodium (Na) and potassium (K) ions than other TMDs, such as MoS2 (molybdenum disulfide) and ReS2 (rhenium disulfide), making it a promising anode material for alkali-ion batteries. Previous studies have found that doping significantly enhances the adsorption and diffusion capabilities of 2D TMDs. For the first time, this work reports the adsorption of Na and K ions on doped TiS2 monolayers using first-principles calculations, where the Ti atom is substituted by 3d-transition metals, including iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu). Metal-atom doping induces remarkably stronger binding of alkali ions on the surface of TiS2, with adsorption energies ranging from −2.07 to −2.48 eV for Na and −2.59 to −3.00 eV for K. The diffusion barrier energies for alkali ions decrease in the proximity of the doping site and increase as the ions travel away from the doping site for Fe-, Co-, and Ni-doped TiS2. The average open circuit voltage increases dramatically when Na ions are adsorbed on Fe-doped TiS2 (by 62%) and Co-doped TiS2 (by 61%), while K ions result in a moderate improvement of 9% and 8%, respectively. These findings suggest that metal-atom doping considerably improves the electrochemical properties of 2D TiS2, potentially enabling its use as anode materials in Na- and K-ion batteries.

First-principles study of ZIF-8 as anode for Na and K ion batteries

Zeolitic imidazolate frameworks (ZIFs) have been investigated experimentally as anodes for Na and K ion batteries. In this work, atomic ZIF-8 models with Zn vacancies have been constructed and the adsorption and diffusion properties of alkali metal atoms are analyzed by density functional theory (DFT) calculations. Zinc vacancies have strong adsorption energy for alkali metal atoms, especially when the first atom is inserted. Additionally, the intercalation of alkali metal atoms would reduce energy band gap of ZIF-8 from 4.85 eV to 4.31 eV for Na and 3.82 eV for K. Moreover, alkali metal atoms can diffuse smoothly in ZIF-8, and the energy barriers are 0.10 eV for Li, 0.45 eV for Na and 0.66 eV for K, respectively. This work deeply explores the interaction mechanism between alkali metals and ZIF-8 theoretically, and provides a reference for the future design of porous carbon materials as anodes for metal ion batteries.

Computational Studies of Super-B as Anodes for AM (Li, Na, and K) Ion Batteries

Energy storage systems have recently become the focus of current research for mankind’s future. This study, as per the features of super-B reported recently, is being explored as an anode material in alkali metal (Li, Na, and K) ion batteries. After adsorption of AM (Li, Na, and K) concentration, the metallic behavior of the super-B remains preserved even at the maximum level. The hollow site (H) appeared as a favorable site among all studied sites for adsorption metal-ion on super-B. Alkali metals adsorption on super-B yielded maximal theoretical capacities of 3718 mhAg−1. The open-circuit voltage (OCV) was found 0.35, 0.81 and 1.39 V for AM (Li, Na, and K) decorated super-B. Furthermore, the lower diffusion barrier was calculated for Li (0.14 eV) and K (0.44 eV) along with the H-T-H, while 0.16 eV for Na along with the H-B-H site. The lower OCV, ultra-fast diffusion barrier, and high specific theoretical capacity show that this newly discovered super-B is a promising candidate to be utilized as an anode material in metal-ion batteries.

Monolayer Ge2S: An auxetic semiconductor with high carrier mobility for metal (Na, K, Mg)-ion battery anodes

Using first-principles calculations, we propose a new two-dimensional Ge2S (space group P21212) with unique mechanical and electronic properties. Monolayer Ge2S has excellent thermal, mechanical, and dynamic stabilities, exhibiting a semiconducting behavior with an indirect bandgap and anisotropic carrier mobility. The uniaxial strain along the zigzag direction can induce an indirect-to-direct bandgap transition. Remarkably, Ge2S possesses large in-plane negative Poisson's ratios, comparable with that of well-known penta-graphene. Moreover, we identify Ge2S as a high-performance anode material for metal-ion batteries. It shows metallic features after adsorbing Na, K, and Mg, providing good electrical conductivity during the charge/discharge process. The diffusion of metal ions on Ge2S is anisotropic with modest energy barriers in the armchair direction of 0.12, 0.39, and 0.76 eV for Na, K, and Mg, respectively. Ge2S can adsorb metal atoms up to a stoichiometric ratio of 1:1, which yields storage capacities of 151.17, 151.17, and 302.35 mA h g−1 for Na, K, and Mg, respectively. The volume of Ge2S shrinks slightly upon the adsorption of metal ions even at high concentrations, ensuring a good cyclic stability. Besides, the average open circuit voltage (0.30–0.70 V) falls within the acceptable range (0.1–1.0 V) of the anode materials. These results make Ge2S a promising anode material for the design of future metal-ion batteries.

First-principles investigation of V2CSe2 MXene as a potential anode material for non-lithium metal ion batteries

The electrochemical performances of the V2CSe2 MXene as anode materials for Na, K, Mg, Ca, and Al-ion batteries have been systematically investigated by the first-principles method. The adsorption energies of metal atoms show that Na, K, and Ca atoms can effectively adsorb on the V2CSe2, except for Mg and Al atoms. The large diffusion constants for Na, K, and Ca atoms calculated by the diffusion energy barriers (0.098 eV for Na, 0.066 eV for Ca, and 0.24 eV for Ca) indicate the high mobility on the V2CSe2 surface. Significantly, the maximum theoretical capacities of V2CSe2 reach up to 394.12 mA h/g for Na and Ca ions. Furthermore, the low average open-circuit voltage (OCV) (0.150 V for Na, 0.175 V for K, and 0.072 V for Ca) indicates the V2CSe2 is a suitable anode material. These results provide fundamental guidance for the V2CSe2 monolayer as anode materials of non-lithium metal-ion batteries.

Theoretical insights into the behaviors of sodium and aluminum on the cathode titanium diboride surfaces

Density functional theory calculations were adopted to systematically investigate the adsorption and diffusion behaviors of sodium and aluminum over TiB2 surfaces or in TiB2 crystal to characterize the interaction mechanism between sodium and TiB2 cathode in aluminum reduction cells. Results suggest that Na and Al will stably adsorbe on the low-index TiB2 (0 0 0 1) surface, and the presence of vacant defects can significantly strengthen this adsorption. The migration of Na and Al over pristine TiB2 is anisotropic, with the largest energy barrier of 0.024/0.32 eV for Na and 0.28/1.57 eV for Al over Ti/B-terminated surfaces. The Ti vacancy in Ti-terminated surface is more effective to hinder Na and Al migration with the large diffusion barriers of 0.36 eV for Na and 2.07 eV for Al. Specially, for the B-terminated surface, B vacancy will promote the Na and Al diffusion with the lower barriers. Additionally, it is difficult for Na and Al to form interstitial defects and diffuse in covalent TiB2 crystal. Given these results, compared to graphite cathode, the sodium prefers to deposit on TiB2 surface, and the strong interaction between sodium and TiB2 promotes the early process of sodium penetration. On the other hand, the smoother landscape for Na diffusion on the TiB2 surface suggests the decreased stability of aluminum liquid, so that the current efficiency of aluminum reduction cell will decrease.