Na-ion Battery Applications Research Articles

Design and Optimization of Iron-Based Superionic-Like Conductor Anode for High-Performance Lithium/Sodium-Ion Batteries.

Metal selenides have received extensive research attention as anode materials for batteries due to their high theoretical capacity. However, their significant volume expansion and slow ion migration rate result in poor cycling stability and suboptimal rate performance. To address these issues, the present work utilized multivalent iron ions to construct fast pathways similar to superionic conductors (Fe-SSC) and introduced corresponding selenium vacancies to enhance its performance. Based on first-principles calculations and molecular dynamics simulations, it is demonstrated that the addition of iron ions and the presence of selenium vacancies reduced the material's work function and adsorption energy, lowered migration barriers, and enhances the migration rate of Li+ and Na+. In Li-ion half batteries, this composite material exhibites reversible capacity of 1048.3 mAh g-1 at 0.1 A g-1 after 100 cycles and 483.6 mAh g-1 at 5.0 A g-1 after 1000 cycles. In Na-ion half batteries, it is 687.7 mAh g-1 at 0.1 A g-1 after 200 cycles and 325.9 mAh g-1 at 5.0 A g-1 after 1000 cycles. It is proven that materials based on Fe-SSC and selenium vacancies have great applications in both Li-ion batteries and Na-ion batteries.

Understanding the NaxMnO2 System: A Thermodynamics and XPS Approach.

The NaxMnO2 system is an important class of materials with potential applications in rechargeable batteries, supercapacitors, catalysts, and gas sensors. This work reports the synthesis of NaxMnO2 (x = 0.39, 0.44, 0.48, 0.66, and 0.70) compounds and their characterization by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and impedance spectroscopy (IS) techniques. The compounds in this series exhibit a significant variation in their structures with the extent of Na-content. The change in the nature of bonding with increasing Na content was investigated, and its effect on material stability as well as electrotransport properties was investigated. A detailed thermodynamic evaluation of these materials was carried out employing calorimetric techniques, and the data were correlated with changes in the chemical environment around the Na ion. This analysis is crucial for predicting the thermodynamic stability of NaxMnO2 compounds under different environments for their applications in Na-ion batteries.

Overcoming Kinetic Limitations of Polyanionic Cathode toward High-Performance Na-Ion Batteries.

Polyanionic cathodes have attracted extensive research interest for Na-ion batteries (NIBs) due to their moderate energy density and desirable cycling stability. However, these compounds suffer from visible capacity fading and significant voltage decay upon the rapid sodium storage process, even if modified through nanoengineering or carbon-coating routes, leading to limited applications in NIBs. Herein, the Na3(VOPO4)2F cathode material with dominantly exposed {001} active facets is demonstrated by a topochemical synthesis route. Owing to the rational geometrical structure design and thereby directly shortening Na diffusion distance, the electrode delivers a reversible capacity of ∼129 mA h g-1 even at a high rate of 10 C, which is very close to the theoretical capacity of 132 mA h g-1, achieving a high energy density of ∼452 W h kg-1 coupled with a high-power density of 4660 W kg-1. When further served as a cathode for nonaqueous, aqueous-based, and solid-state full NIBs, respectively, our designed Na3(VOPO4)2F always enables superior electrochemical performance due to favorable kinetics.

Biotene: Earth-Abundant 2D Material as Sustainable Anode for Li/Na-Ion Battery.

Natural ores are abundant, cost-effective, and environmentally friendly. Ultrathin (2D) layers of a naturally abundant van der Waals mineral, Biotite, have been prepared in bulk via exfoliation. We report here that this 2D Biotene material has shown extraordinary Li-Na-ion battery anode properties with ultralong cycling stability. Biotene shows 302 and 141 mAh g-1 first cycle-specific charge capacity for Li- and Na-ion battery applications with ∼90% initial Coulombic efficiency. The electrode exhibits significantly extended cycling stability with ∼75% capacity retention after 4000 cycles even at higher current densities (500-2000 mA g-1). Further, density functional theory studies show the possible Li intercalation mechanism between the 2D Biotene layers. Our work brings new directions toward designing the next generation of metal-ion battery anodes.

Nitrogen doped soap-nut seeds derived hard carbon as an efficient anode material for Na-ion batteries

Biomass-derived hard carbon materials have received promising research interest because of their low cost, high abundance, and renewability. In the present study, high-performance hard carbon material is prepared from soap-nut seeds (SNS-0) using a simple pyrolysis process. Further, N (nitrogen) heteroatoms are introduced into the hard carbon matrix to modify its structure using melamine as the N source. High-resolution transmission electron microscopy images reveal the development of the localized graphite-like structure after the introduction of N atoms in the hard carbon, which are found to be beneficial for the storage and transport of the larger Na ions in the battery. The optimal doping of N (1:1 wt. ratio, SNS-1) in the hard carbon has improved the storage performance of the SNS-0 electrode, providing a reversible capacity of 353 mA h g−1 at a current density of 25 mA g−1. The improved electrochemical characteristics of the SNS-1 electrode over the other compositions are associated with its lesser specific surface area (282.87 m2 g−1) and higher interlayer spacing (0.38 nm). The present study not only reveals the useful conversion of a biomass waste, soap-nut seeds, into a low-cost and sustainable eco-friendly hard carbon material but also its potential use as an efficient anode for Na-ion battery applications.

Monolayer TiSiP as a high-performance anode for Na-ion batteries

Exploring anode materials with overall excellent performance remains a great challenge for rechargeable Na-ion battery technologies. Herein, we have identified that monolayer TiSiP is just such a prospective anode candidate via first-principles calculations. It is showed to be dynamically, thermally, mechanically, and energetically stable, which provides feasibility for experimental realization. The Na diffusion on the its surface is proved to be ultrafast, with a migration energy barrier as low as 73 meV. Electronic structure confirms that the pristine system undergoes a transition from the semiconductor to metal during the whole sodiation process, which is a significant advantage to the electrode conductivity. More excitingly, monolayer TiSiP can accommodate up to double-sided five-layer adatoms, resulting in an ultrahigh theoretical capacity of 1176 mA h g−1 and a low average open-circuit voltage of 0.195 V. Moreover, the maximally sodiated electrode monolayer yields rather small in-plane lattice expansion of only 1.40%, which ensures reversible deformation and excellent cycling stability as further corroborated by structural relaxation and ab initio molecular dynamics simulation. Overall, all of these results point to the potential that monolayer TiSiP can serve as a promising anode candidate for application in high-performance low-cost Na-ion batteries.

Solvothermal Engineering of NaTi2(PO4)3 Nanomorphology for Applications in Aqueous Na-Ion Batteries.

Aqueous Na-ion batteries are among the most discussed alternatives to the currently dominating Li-ion battery technology, in the area of stationary storage systems because of their sustainability, safety, stability, and environmental friendliness. The electrochemical properties such as ion insertion kinetics, practical capacity, cycling stability, or Coulombic efficiency are strongly dependent on the structure, morphology, and purity of an electrode material. The selection and optimization of materials synthesis route in many cases allows researchers to engineer materials with desired properties. In this work, we present a comprehensive study on size- and shape-controlled hydro(solvo)thermal synthesis of NaTi2(PO4)3 nanoparticles. The effects of different alcohol/water synthesis media on nanoparticle phase purity, morphology, and size distribution are analyzed. Water activity in the synthesis media of different alcohol solutions is identified as the key parameter governing the nanoparticle phase purity, size, and shape. The careful engineering of NaTi2(PO4)3 nanoparticle morphology allows control of the electrochemical performance and degradation of these materials as aqueous Na-ion battery electrodes.

Energy efficient lattice and surface chemical regeneration of graphite from failed Li-ion batteries and its use as ultra-long cycling Na-ion battery anodes

Graphite being the most used anode in commercial lithium ion batteries (LIBs), haven't receive much attraction in recycling research. Also, graphite has limited attraction for Na-ion battery (NIB) applications due to poor intercalation. Tackling both these issues together, we present energy efficient recycling strategies for spent graphite (SG) delivering high rate and ultra-long cycling in NIBs. Three regeneration processes without high temperature annealing is reported, (i) solvent treatment (ii) solvent+acid and (iii) microwave assisted hydrothermal processing. Comprehensive structural, chemical and morphological characterizations were carried out for correlating with the performance. The solvent+acid treated SG exhibited ultra-long cycling stability (>36,000 cycles) and subsequently failed, delivering capacity retention of 97%. Whereas, microwave processed SG delivered 50,000 cycles without fail and 89% retention. In comparison, as-recovered SG failed within few thousand cycles under-same conditions. These unprecedented results establish that SG regenerated with energy efficient process is a potential anode for long-life NIB applications.

Sustainable and scalable fabrication of high-performance hard carbon anode for Na-ion battery

Sustainable and green manufacturing of hard carbon (HC) material in a low-cost way is the key issue in promoting its industrial applications in Na-ion batteries (SIB). Nowadays, most synthesis ways to prepare HC need the help of chemical reagents to improve its Na-ion storage performance. Herein, we firstly developed a completely green biological fermentation technology to prepare HCs on a large scale using cheap and renewable carbon sources of various biomass starch. Pre-treatment by bio-fermentation can effectively modify the carbon precursor for facile pyrolysis to fabricate starch-based HCs, and make its internal microstructure with larger interlayer spacing, more disordered structure and abundant closed micropores. Finally, a case of cornstarch-based hard carbon exhibits a high reversible capacity of 335 mA h g−1 at a current density of 30 mA h g−1 and high rate performance with a reversible capacity of 140.6 mA h g−1 even at a high current of 5 A g−1 as well as long cycling stability. In-situ Raman spectra, ex-situ SAXS and ex-situ XPS tests during discharge and charge process reveal the pore filling mechanism of quasi-metallic Na in hard carbon anode. Such a “bread-making”strategy is a facile and scalable route to fabricate various starch-based hard carbons with improved performance, demonstrating a very practically promising application for industrial manufacture.

Tuning discharge voltage by Schottky electron barrier in P2-Na2/3Mg0.205Ni0.1Fe0.05Mn0.645O2

Recently, Mg doped Na metal oxide layered cathode compounds have attracted strong interest for Na-ion battery applications. Here a new type of asymmetric phase evolution between charge and discharge is found to show much-enhanced discharge voltage in P2-Na2/3Mg0.205Ni0.1Fe0.05Mn0.645O2 over the parent cathode compound. P2 solid solution is found to show an abnormal coexistence with O2-P2 two-phase reaction during discharge with simultaneous reduction of O, Ni, and Fe redoxes, distinct from the conventional P2-O2 two-phase reaction in the charge. Our analysis suggests that the P2 and O2 two-phase boundary forms a novel unidirectional Schottky barrier to impede electron and Na diffusions in discharge only, thus making the kinetically preferred P2 solid solution phase abnormally coexist with the two-phase region for high discharge voltage and low polarization. Our work demonstrates tuning dynamic evolution of electronic Schottky barrier as a new dimension for advanced kinetic design of high-performance battery cathode materials.

Next generation sodium-ion battery: A replacement of lithium

The demands for Sodium-ion batteries for energy storage applications are increasing due to the abundance availability of sodium in the earth’s crust dragging this technology to the front raw. Furthermore, researchers are developing efficient Na-ion batteries with economical price and high safety compared to lithium to replace Lithium-ion batteries. The performance of sodium-ion batteries significantly depends on the cathode; anode and electrolyte components. In the present review paper, we discuss cathode, anode, solid electrolyte, binders and addictives properties and their performance. Furthermore, the strong and weak points of every metal and compound were discussed and analyzed in this paper. A detailed comparison of the electrical conductivity performance of solid electrolyte materials is done to find their suitability for next-generation Na-ion battery applications.

Multi-layered MXene V4C3Tx as new low-voltage insertion anode for Na-ion battery applications

We report an MXene V4C3Tx new low-voltage insertion anode and a comparison of the electrochemical performance with ester and ether-based electrolytes in half– and full–cell configuration with Na3V2(PO4)3@C (NVPC). Though MXene has been explored for Na-ion batteries (SIB), Mn+1XnTx with n = 3 has been hardly explored. Moreover, the ether-based electrolyte has not been used with any MXenes for electrochemical energy storage, especially in the SIB perspective. The initial irreversibility in the carbonate-based half–cell (V4C3Tx–C) is 128 mAh g−1 more than the tetraglyme–based half–cell (V4C3Tx–T). After 100 cycles, V4C3Tx–T maintains 84 mAh g−1, while V4C3Tx–C shows only 60 mAh g−1, which shows the better retention ability in the ether-based system. As for the rate performance, though V4C3Tx–T has a higher capacity in low currents, at higher currents, V4C3Tx–C shows higher values. This showed that the carbonate-based system has diffusion and capacitive-based Na–ion storage, which enabled it to have a high–rate performance. An extensive in–situ impedance study revealed significant formation of the passivation layer in V4C3Tx–C by irreversibly consuming Na–ions, which causes an increased initial Coulombic inefficiency, whereas no such significant SEI layer formation is evident for V4C3Tx–T. Full–cells were assembled with NVPC cathode in tetraglyme and carbonate-based electrolytes. The full–cell with ether electrolyte exhibited enhanced capacity, capacity retention, and rate performance compared to ester-based electrolytes. The full-cell displayed an energy density of ∼66 and ∼74 Wh kg−1 for tetraglyme and ester-based electrolytes, respectively.

Fluorine substitution enabled superior performance of NaxMn2-xO1.5F0.5 (x = 1.05–1.3) type Na-rich cathode

Among the various sodium cathodes, the potential of Na-rich layered oxides is yet to be fully utilized. Unlike their Li counterparts, they are least explored and are at least a generation behind in development. Addressing the same, herein, Na-rich NaxMn2-xO1.5F0.5 (x = 1.05–1.3) type cathodes were synthesized successfully and analyzed as potential electrodes for Na-ion battery applications. Oxygen loss in Na-based transition metal oxides is a common issue, and it is effectively addressed by fluorine substitution. In contrast to exploring a particular stoichiometry as in other Na-deficient layered cathodes, herein, Na-content was gradually increased from 1.05 to 1.3. The cathodes were synthesized using a conventional solid-state approach and quenched to achieve high crystallinity. Compounds with different sodium stoichiometry were electrochemically tested in a half-cell configuration. Among these compounds, the Na1.2Mn0.8O1.5F0.5 electrode exhibited very high capacities of 178 and 122 mAhg−1 at current densities of 10 and 1000 mA g−1, respectively. The Na-rich Na1.2Mn0.8O1.5F0.5 cathode was systematically analyzed to understand the mechanism underlying its superior performance using various structural and electrochemical analyses. Furthermore, to demonstrate its practicality, the Na-rich Na1.2Mn0.8O1.5F0.5 cathode was coupled with a hard carbon and Na-In alloy anode in a full-cell assembly.

Resolving the Role of Configurational Entropy in Improving Cycling Performance of Multicomponent Hexacyanoferrate Cathodes for Sodium‐Ion Batteries (Adv. Funct. Mater. 34/2022)

Configurational Entropy In article number 2202372, Yuan Ma, Ben Breitung, Torsten Brezesinski, and co-workers report the preparation and characterization of Mn-based multicomponent hexacyanoferrate cathodes for application in Na-ion batteries. Systematic comparison of the structural, chemical, and electrochemical properties of high-, medium- and low-entropy materials uncover the origin of improved cycling performance and stability, namely entropy-mediated suppression of adverse side reactions and phase transitions.

New insights to build Na+/vacancy disordering for high-performance P2-type layered oxide cathodes

P2-type Na-based layered oxides are potential cathode materials for high power Na-ion batteries (NIBs). However, complex Na+/vacancy ordering rearrangement evidenced by obvious voltage plateaus in the electrochemical profiles severely affects the Na storage capacities and cycling stability, hindering the commercialization of P2 materials. Herein, we show that the unfavorable rearrangement can be avoided by pre-forming lower Na content P2 materials with a delocalized electronic structure and modulated site energy difference between Naf and Nae, as demonstrated by DFT calculations. The disordered framework and enlarged interlayer spacing can be sustained throughout the whole electrochemical process, ensuring both a wider solid-solution region and smaller volume change during de-/sodiation. As a consequence, an excellent electrochemical performance, namely a high reversible capacity of 165.1 mAh g−1, a superior rate performance of 76.7% of capacity retention at 1000 mA g−1, and 91.7% capacity retention after 150 cycles, is harvested. Moreover, this strategy is universal and can be used to synthesize various disordering high-capacity P2 materials. This work provides a long-neglected and unexpected idea for improving the comprehensive performance of P2-type materials for facilitating their practical applications in NIBs.

DFT studies on electrochemical properties of halide ions doped GDY-28 nanoflake for Na-ion battery applications

Efficiency of pristine and halogens doped graphdiyne analogue (GDY-28) is theoretically investigated for application as anode material in sodium ion batteries (NIBs). In this scenario, density functional theory (DFT) calculations are implemented to study electrochemical properties of Na/X@GDY-28 and Na+/X@GDY-28 (X = F−, Cl− and Br−) complexes in the presence of carbon tetracholride solvent. Na and Na+ prefer to adsorb in the middle of GDY-28 nanoflake. The adsorption energy (Ead) of Na+ is stronger as compared to Na for both pristine and halides doped GDY-28, Ead of Na + on GDY-28 in Na+@GDY-28 is −661.90 kcal mol−1. However, the calculated Gibbs free energy and cell voltage of pristine GDY-28 nanoflake are −3.82 kcal mol−1 and 0.17, respectively. Adopting a strategy of doping halides on GDY-28 nanoflake considerably increased the Gibbs free energy, which resulted in the enhancement of cell voltage. The cell voltage of these systems is increased from 0.17 V (for pristine GDY-28) to 0.20 V–0.52 V (for X−@GDY-28 (X− = F−, Cl− and Br−)). A monotonic increase in cell voltage is noticed with increase in electronegativity of halide ion. The reason is strong binding of Na+ with more electronegative halide ion doped GDY-28 nanoflake. The highest ΔG (−12.00 kcal mol−1) and cell voltage (0.52 V) is reported for Na/F@GDY-28 complex in the presence of carbon tetracholride.

Development of advanced electrolytes in Na-ion batteries: application of the Red Moon method for molecular structure design of the SEI layer.

This review aims to overview state-of-the-art progress in the collaborative work between theoretical and experimental scientists to develop advanced electrolytes for Na-ion batteries (NIBs). Recent investigations were summarized on NaPF6 salt and fluoroethylene carbonate (FEC) additives in propylene carbonate (PC)-based electrolyte solution, as one of the best electrolytes to effectively passivate the hard-carbon electrode with higher cycling performance for next-generation NIBs. The FEC additive showed high efficiency to significantly enhance the capacity and cyclability of NIBs, with an optimal performance that is sensitive at low concentration. Computationally, both microscopic effects, positive and negative, were revealed at low and high concentrations of FEC, respectively. In addition to the role of FEC decomposition to form a NaF-rich solid electrolyte interphase (SEI) film, intact FECs play a role in suppressing the dissolution to form a compact and stable SEI film. However, the increase in FEC concentration suppressed the organic dimer formation by reducing the collision frequency between the monomer products during the SEI film formation processes. In addition, this review introduces the Red Moon (RM) methodology, recent computational battery technology, which has shown a high efficiency to bridge the gap between the conventional theoretical results and experimental ones through a number of successful applications in NIBs.

O3-NaFe(1/3-x)Ni1/3Mn1/3AlxO2 Cathodes with Improved Air Stability for Na-Ion Batteries.

Na-ion batteries (NIBs) have been considered as potential candidates for large-scale energy storage, where O3-type Na-based layered oxide cathodes have attracted great attention due to their high capacity and low cost. However, O3-NaxTMO2 materials still suffer from insufficient air stability, which could lead to deteriorative electrochemical properties and thus hinder their practical application. In this work, a series of Al-doped O3-NaFe(1/3-x)Ni1/3Mn1/3AlxO2 cathodes prepared by a co-precipitation method were investigated to enhance their electrochemical performance and air stability through stabilizing their structural and interface chemical properties. The Al-doped O3-NaFe(1/3-0.01)Ni1/3Mn1/3Al0.01O2 (NFNMA0.01) cathode delivers a comparable capacity of 138 mAh g-1 and keeps a capacity retention of 85.88% after 50 cycles at 0.2 C, while the undoped O3-NaFe1/3Ni1/3Mn1/3O2 (NFNM) can only keep a capacity retention of 71.02%, although with an initial capacity of 141 mAh g-1 at 0.2 C. For the air stability, the capacity decay rates are 58.87 and 5.07% for the undoped NFNM and Al-doped NFNMA0.01 after the air exposure for 30 days, respectively. The greatly decaying electrochemical performance could be due to the formation of carbonates during air exposure, which can be efficiently suppressed by Al doping. The doped Al3+ has been confirmed to be inserted into the NFNM crystal lattice, inducing the reduced values of lattice parameters a and c due to the smaller ionic radius of Al3+ (53.5 pm) vs Fe3+ (55.0 pm). This study demonstrates that Al doping plays an important role in the air stability and cycling stability for layered cathode materials, which offers an efficient strategy to optimize the material design for their practical application in NIBs.

Understanding the sodium-ion dynamics in NASICON (Na3Al2P3O12) glass containing NaF: Scaling of electrical conductivity spectra

Quest for high ion-conducting solid electrolyte materials for sodium-ion batteries has been tremendously increasing. Glass materials are a potential solid electrolyte for high-energy Na-ion batteries. Nevertheless, the effective research on glass materials for their applications in Na-ion batteries is dawdling due to its low ionic DC-conductivity and poor understanding of the dynamics of mobile cations. Herein, we have attempted to address the effect of substitution of NaF for Al2O3 on the conductivity of Na3Al2P3O12(NAP) glass (mol%: 37.5P2O5–25.0Al2O3–37.5 Na2O). Raman spectra reveal that the increase in the substituent NaF concentration significantly affects the coordination of Al3+ and the distribution of sodium cations in the network structure of NAP glass. Impedance spectra reveal that the change in conductivity of NAP glass with an increase in the NaF concentration is highly dependent on a specific temperature range. At a lower temperature range, (<150 °C), the conductivity increases initially with the increase in NaF concentration and it decreases with any further increase in the NaF concentration; whereas, at temperatures above 150 °C, the conductivity increases continuously with an increase in the NaF concentration. The frequency-dependent AC-conductivity has been analyzed using the time-temperature scaling principle (TTSP) based on Summerfield and Ghosh scaling procedures to probe the ion conduction mechanism. The NAP glass that contains low NaF concentrations (<7.5 mol%) obeys the AC-conductivity scaling, i.e., it satisfies the TTSP principle, with respect to temperature based on the Summerfield scaling procedure; this indicates that the sodium-ion dynamics are independent of the temperature. The scaled AC-conductivity curves for NAP glass containing high NaF concentrations (>10 mol%) have deviated from Summerfield scaling and further indicate that the fraction of sodium-ions responsible for the ionic conductivity is decreasing with an increase in the temperature. Scaling of AC-conductivity curves for all the glass samples using the Ghosh procedure suggests that the number density along with the hopping distance of sodium ions changes with increasing temperature. The Modified random network structural model has been further utilized to explain the variation in the NAP glass conductivity with an increase in the NaF concentrations. The outcome of this work will certainly aid in designing the chemical compositions of glasses for the development of solid electrolyte materials for their applications in Na-ion batteries.

Influence of synthesis methodology and excess Na on the ionic transport properties of natrium super ionic conductor, Na3Zr2Si2PO12

Na3Zr2Si2PO12 is a well-known solid electrolyte because of its potential applications in Na-ion batteries and gas sensors. In this work, the structural and transport properties of Na3Zr2Si2PO12 synthesized by solid-state reaction and sol–gel techniques are compared. In both methods, a monoclinic phase for Na3Zr2Si2PO12 is confirmed by X-ray Diffraction and FTIR spectroscopy techniques. The impedance measurements show higher conductivity in Na3Zr2Si2PO12 prepared by solid-state reaction. The role of sintering temperatures on the transport results of Na3Zr2Si2PO12 has been investigated. The temperature dependent conductivity plots of Na3Zr2Si2PO12 show a change in the slope at 163 °C corresponding to its structural phase transition from monoclinic to rhombohedral form, which is further supported by its DSC result. Furthermore, the role of excess Na on the ionic conductivity of Na3Zr2Si2PO12 using two different Na precursors Na2CO3 and Na3PO4 keeping same Na-stoichiometry has been investigated.