Sodium-ion Batteries Research Articles

Synergistic effect of NASICON Na3V2(PO4)2F3 and 2D MXene for high-performance symmetric Sodium-ion batteries

Sodium fluorophosphate-based Na3V2(PO4)2F3 (NVPF) cathode materials have been widely analyzed in Sodium-ion batteries (SIB) owing to their high energy density and high working voltage. However, the low electronic conductivity of NVPF is a factor hindering their efficient use. To enhance the electronic conductivity of NVPF, in this work, a porous Na3V2(PO4)2F3 and a 2D Ti3C2-based MXene nanocomposite was synthesized using a facile sol-gel method. The NVPF, with the presence of two active redox couples, is a suitable choice for symmetric batteries. The NVPF + 2D MXene nanocomposite was analyzed for its structural and thermal characteristics, and a symmetric cell prepared from them was investigated for its electrochemical characteristics. Structural analysis of the materials developed indicates that the MXene addition has not altered the crystal structure of the NVPF. A remarkable improvement in the electrochemical performance of NVPF in the sodium symmetric cell is noticed, as indicated by its high specific discharge capacity of 92mAhg-1 at 1C for the MXene-incorporated composite structures. This improvement in electrochemical behaviour is confirmed in the rate capability curves, GCD curves, and GITT curves. The diffusion coefficient values obtained from GITT analysis showed improved kinetics in the synthesized material due to the MXene incorporation. The calculated values of the diffusion coefficient of Na+confirms the accelerated kinetics of Na+ ion migration during the intercalation/de-intercalation process in the MXene 5wt% nanocomposites, with a value of 9.57 × 10–9 cm2s-1 when compared to 4. 14 × 10–9 cm2s-1 for the pristine sample.

Cu-doped graphene Cu/N2OG: A high-performance alkaline metal ion battery anode with record-theoretical capacity

Anode materials are paramount in dictating the performance of ion batteries. Therefore, the judicious design of novel anode materials boasting superior capacity is crucial to further enhancing the energy density of ion batteries. This study employs first-principles computational methods to systematically investigate the performance of Cu-doped graphene 2D material (Cu/N2OG) as an Li-ion batteries (LIBs), Na-ion batteries (NIBs), or K-ion batteries (KIBs) anode. Simulation results indicate that the structural asymmetry introduced by Cu doping significantly increases the active sites of the material, enhancing its theoretical specific capacity for Li/Na/K. Notably, the sodium storage theoretical capacity of Cu/N2OG reaches an impressive 3303.7 mAh/g, surpassing the capacity of all currently employed NIBs anode materials. Furthermore, Cu/N2OG also boasts high theoretical capacities, yielding capacities of 1651.8 mAh/g for LIBs and 1263.2 mAh/g for KIBs, respectively. The material retains excellent conductivity both prior to and following the adsorption of Li, Na, and K. Furthermore, Cu/N2OG demonstrates a low diffusion barrier and minimal lattice changes (<1 %), suggesting its potential as a high-performance anode for LIBs/NIBs/KIBs.

Revealing stable organic cathode/solid electrolyte interface to promote all-solid-state sodium batteries using organic cathodes

Revealing stable organic cathode/solid electrolyte interface to promote all-solid-state sodium batteries using organic cathodes

Breaking boundaries in O3-type NaNi1/3Fe1/3Mn1/3O2 cathode materials for sodium-ion batteries: An industrially scalable reheating strategy for superior electrochemical performance

To address the challenges of air stability and slurry processability in layered transition metal oxide O3-type NaNi1/3Fe1/3Mn1/3O2 (NFM) for sodium-ion batteries (SIBs), we have designed an innovative 500 °C reheating strategy. This method improves the surface properties of NFM without the need for additional coating layers, making it more efficient and suitable for large-scale applications. Pristine NFM (NFM-P) was first synthesized through a high-temperature solid-state method and then modified using this reheating approach (NFM-HT). This strategy significantly enhances air stability and electrochemical performance, yielding an initial discharge specific capacity of 151.46 mAh/g at 0.1 C, with a remarkable capacity retention of 95.04% after 100 cycles at 0.5 C. Additionally, a 1.7 Ah NFM||HC (hard carbon) pouch cell demonstrates excellent long-term cycling stability (94.64% retention after 500 cycles at 1 C), superior rate capability (86.48% retention at 9 C), and strong low-temperature performance (77% retention at −25 °C, continuing power supply at −40 °C). Notably, even when overcharged to 8.29 V, the pouch cell remained safe without combustion or explosion. This reheating strategy, which eliminates the need for a coating layer, offers a simpler, more scalable solution for industrial production while maintaining outstanding electrochemical performance. These results pave the way for broader commercial adoption of NFM materials.

NiS2/FeS2 binary nanoparticles confined in interconnected carbon framework with regulated pore structure enabled by citric acid for enhanced sodium storage properties

Recently, pyrite iron disulfide (FeS2) has emerged as a promising anode candidate for sodium-ion batteries (SIBs) due to its high theoretical capacity, affordability, non-toxicity and abundant resource in nature. However, the utilization of FeS2 still confronts the challenges of inferior rate capability and cycling instability for sodium storage, stemming from its low electronic conductivity and substantial volume changes during cycling. Herein, to address these obstacles, NiS2/FeS2 binary nanoparticles encapsulated within a network of interconnected N-doped porous carbon framework (NiS2/FeS2@NPC) are prepared by a successive solid-state ball milling, carbonization and sulfurization strategy with coordination complex of nickel iron Prussian blue analogue (NiFe-PBA) as precursor. The introduction of citric acid plays a critical role for the formation of interconnected carbon framework with regulated internal porous structure, thereby achieving heterostructured NiS2/FeS2@NPC with modulated specific surface area and pore volume. The rational design of interconnected N-doped porous carbon framework and heterogeneous structure guarantees rapid ion/electron transport kinetics, alleviated mechanical stress, and enhanced structural integrity. Benefitting from these advantages, the optimal NiS2/FeS2@NPC-1 electrode exhibits a high reversible capacity (545 mAh/g at 1 A/g), superior rate capability (267 mAh/g at 5 A/g) and ultrastable long-term cycling performance (98.5 % retention over 1000 cycles at 5 A/g). This study presents a novel and efficient design approach for creating durable and high-rate anode materials based on metal sulfides for SIBs.

Influence of calcium-doped on the conductivity of NASICON-type Na3Zr2Si2PO4 solid electrolyte

Sodium-ion solid electrolyte has many advantages such as high safety, good ionic conductivity, and strong chemical stability. NASICON-type Na3Zr2Si2PO4 solid electrolyte was prepared by high-temperature Solid State Reaction (SSR). X-ray Diffraction (XRD) show that the 20% excess addition of Na and P elements will reduce the formation of ZrO2 impurity phase and increase the ionic conductivity to 1.01×10−4 S cm−1. On the basis of this experiment, Ca was added to dope the Na site in Na3Zr2Si2PO4 with different contents. Electrochemical impedance spectroscopy (EIS) results show that the conductivity of Ca2+ doped Na2.7Ca0.15Zr2Si2PO4 is significantly increased to 1.53×10−4 S cm−1, the electronic conductivity is 3.99×10−8 S cm−1, and the activation energy is 0.32 eV. Cyclic voltammetry testing demonstrated stable chemical properties below to 5 V. Na | Na2.7Ca0.15Zr2Si2PO4 | Na3V2(PO4)3 battery still maintains a high capacity retention rate of 98.76% after 200 cycles at 25oC-0.2C. It indicating that the new 0.15molCa-doped Na2.7Ca0.15Zr2Si2PO4 has the highest electrical conductivity, which provides a new research idea for sodium-ion solid-state batteries and has great potential in solid-state battery applications.

Dual-site defects engineering to eliminate impurities and optimize reversible reaction kinetics of Na4Fe3(PO4)2P2O7 cathode for superior performance sodium ion batteries

Na4Fe3(PO4)2P2O7 is a prominent polyanionic material widely studied as a cathode for sodium-ion batteries, valued for its stable cycling performance and cost-effectiveness. However, the sluggish diffusion kinetics of Na+ associated with electrochemically inert NaFePO4 impurities during synthesis strictly limit the rate performance and energy density of Na4Fe3(PO4)2P2O7. In this study, dual-site defects engineered Na4-2xFe3-1.5yLay(PO4-xBrx)2P2O7 cathode materials were synthesized using a facile mechanical activation method, by introducing trace amounts of LaBr3 as additive. Fe defects originating from La doping eliminate the maricite-NaFePO4 inert impurities and Na defects stemming from Br doping optimize the microchemical valence states and ion transport kinetics. The density functional theory demonstrates that Fe/Na dual-site defects in the lattice of Na4Fe3(PO4)2P2O7 reduce band gap and facilitate Na+ migration passageway, thereby leading to a superior rate capability and stable sodium storage performance. Moreover, the sodium storage mechanism of the dual-site defects engineered Na4Fe3(PO4)2P2O7 cathode material is revealed. The optimal dual-site defects engineered cathode sample delivers excellent rate performance (55.2 mAh g-1 at 50 C) and long cycling stability (capacity retention of 93% after 2000 cycles at 10 C). This study provides a promising strategy for engineering dual-site defects to synthesize impurities-free Na4Fe3(PO4)2P2O7 cathode material with superior electrochemical performance.

Conduction channel creation by interstitial site engineering in otherwise insulating Na6ZnS4 for Na-conducting solid-state electrolytes

Na5.6Zn0.6Ga0.4S4, which retains the crystalline structure of its parent form Na6ZnS4, is described as a new class of Na-conducting solid-state electrolytes (SSEs) for all-solid-state batteries. We demonstrate that while Na6ZnS4 is ionically insulating (1.4 nS cm-1), Ga-substitution results in an astonishing improvement of ionic conductivity (σion) to 70.1 μS cm-1, making Na5.6Zn0.6Ga0.4S4 a practical SSE. This dramatic increase in σion (5 × 104 fold) is associated with an increased Na+ occupancy in interstitial sites as ‘x’ increases in Na6-xZn1-xGaxS4, where interstitial Na ions facilitate long-range Na+ conduction, which is otherwise immobile. Ga-substitution also results in phase-pure Na6-xZn1-xGaxS4, contributing at least partially to the enhancement of σion. Furthermore, Na6-xZn1-xGaxS4 exhibits neither releasing H2S gas nor compromising its crystalline structure for several hours under ambient conditions. Ga-substitution also enhances electrochemical stability. While the anodic limit remains largely unchanged, the cathodic limit is significantly lowered from 0.99 V vs. Na2Sn in Na6ZnS4 to 0.35 V in Na5.6Zn0.6Ga0.4S4, resulting in stable Na alloying/dealloying reactions in a symmetric Na2Sn ‖ Na2Sn cell. These findings are comprehensively supported by various experimental and theoretical methods. Finally, we construct a full cell (Na2Sn ‖ TiS2) and demonstrate the practicality of Na5.6Zn0.6Ga0.4S4 as a promising SSE in all solid-state Na ion batteries.

Mixed-dimensional van der Waals heterostructure of Bi2S3 nanorods and SnS2 nanosheets bridged with N-doped carbon interlayer for enhanced sodium-ion batteries

Mixed-dimensional van der Waals heterostructure of Bi2S3 nanorods and SnS2 nanosheets bridged with N-doped carbon interlayer for enhanced sodium-ion batteries

Ultrafast Lattice Engineering for High Energy Density and High-Rate Sodium-Ion Layered Oxide Cathodes

Sodium-ion batteries attract significant interest for large-scale energy storage owing to abundant sodium reserves, while challenges remain in the high synthesis energy consumption, long synthesis period, and poor electrochemical performance of sodium-ion layered oxide materials. This study presents a general high-temperature thermal shock (HTS) strategy to synthesize and optimize sodium-ion layered oxides. The rapid ramping, sintering, and cooling processes minimize volatile sodium loss during HTS, facilitating the improvement of phase purity and effectively optimizing the microstructure of materials in a non-equilibrium state. As a proof of concept, Mn-based Na0.67MnO2 treated with HTS (NMO-HTS) suppresses Mn ion vacancy within transition material layers, thereby increasing the redox centers and lowering the Mn 3d orbital energy level. Besides, the formation of transition metal layer stacking faults mitigates the structural transformation and Na+-vacancies ordering arrangement during cycling. Consequently, the energy density of the NMO-HTS increases by 21.5% to 559 Wh kg-1, with an outstanding rate capability of 108 mAh g-1 at 10C and an impressive capacity retention of 93.7% after 300 cycles at 1C. In addition, we demonstrate the universality of HTS in synthesizing various other sodium-ion layered oxides, including nickel-based and iron-based cathodes, as well as in activating degraded materials.

Six element high-entropy Prussian blue analogue cathode enabling high cycle stability for sodium-ion batteries

Prussian blue analogues (PBA) are promising cathode materials for sodium-ion batteries. However, the cycle life of PBA is limited due to its structure instability during cycling. Here, we successfully introduce six transition metals into N coordination site to increase the configurational entropy, significantly improving the structure stability and cycle life of PBA cathode materials. Electrochemical characterization methods are used to compare the behavior of hexa-, penta-, quadr-, and tri-metal PBA, exhibiting the characteristic of performance increasing with entropy. Time-resolved in situ X-ray diffraction confirms the “quasi-zero-strain” structure of H-PBA during desodiation/sodiation process. X-ray absorption spectroscopy and density functional theory calculations reveal that Mn, Fe, Co and Cu contribute the high capacity of H-PBA, while Ni and Zn stabilize the structure. The strategy will inspire new ideas in designing long life cathode materials with high capacity for sodium-ion batteries.

Recovery of all-solid-state sodium-ion batteries cathode and solid electrolyte using deep eutectic solvents as green solvents

Recovery of all-solid-state sodium-ion batteries cathode and solid electrolyte using deep eutectic solvents as green solvents

Insights into the ternary substitution Na2.96+xK0.04 V2-xNix(PO4)2.98F0.06 with superior rate capability and near-zero strain property

Na3V2(PO4)3 (NVP) is considered the most favorable cathode for sodium-ion batteries due to its solid NASICON skeleton. Nevertheless, poor intrinsic conductivity is insufficient for its further commercialization. In this paper, we present a promising K/Ni/F co-doped and carbon nanotubes (CNTs) encapsulated Na2.96+xK0.04 V2-xNix(PO4)2.98F0.06 (KNF@CNTsx) cathode materials. The synthesis of KNF@CNTsx is achieved using a facile sol-gel method. The replacement of Na+ with K+ broadens the migratory pathway and supports the crystal skeleton, while F− substitution reduces the average grain dimension, thereby increasing the diffusion rate of Na+. Furthermore, the reduction of resistance by Ni2+ doping enables optimization of the transport of electrical charge, while also facilitating the optimization of chemically-defined properties. Concurrently, the optimal quantity of carbon capping and wrapping of CNTs facilitate the formation of efficacious conductive network, which diminishes the size of grains and shortens the pathway for the diffusion of Na+. This network could also serve as a buffer against crystal deformation. In conclusion, the modified KNF@CNTsx samples exhibit notable enhancements in their conductivity, ion diffusion capacity, and structural stability. Among them, the KNF@CNTs0.04 sample exhibits a capacity for reversibility of 93.3 mAh g−1 at 50C, with a remaining capacity of 68.5 mAh g−1 after 4000 successive long charge-discharge cycles. Ex-situ electrochemical XRD demonstrates the V3+/V4+ redox reaction occurs accompanied by the phase transfer reaction, during which Na+ prefers to diffuse along c-axial in the crustal structure. Moreover, volume alteration of this KNF@CNTs0.04 cellular entity is miniscule and reversible during the charge-discharge process, further confirming the stabilized construction and near-zero strain property. The after-cycled XRD/SEM/XPS certify the improved chemical and structural stability of KNF@CNTs0.04, indicating the constructive effects of K/Ni/F ternary substitution.

High-efficient sodium compensation enabled by dual-carbon coupling catalyst strategy for sodium-ion batteries

Sodium oxalate (Na2C2O4), a green, cost-effective, and high-capacity additive candidate, suffers from a decomposition voltage that largely exceeds the cutoff voltage of currently common layered oxides and polyanionic compounds, limiting its availability. This work constructs a composite structure of carbon-coated Na2C2O4 coupled with a catalyst-loaded Ketjen black (NCO@C@MMNKB) using a low-temperature carbon-coated assisted ball milling technique. The results show that the decomposition potential of Na2C2O4 is significantly reduce from 4.42 to 3.91 V. Meanwhile, correspondingly the full cell energy density is enhanced from 135.0 to 236.4 Wh Kg−1. Further investigations show that the by-products of the sodium compensation additive exhibit different “gas effects” on the formation of the cathode and anode solid electrolyte interphase (CEI and SEI) films. This provides a practical thought to promote similar additives towards practicality to improve the overall performance of SIBs.

Nitrogen-doped carbon coated Na3V2O2(PO4)2F as a cathode for high-performance sodium-ion batteries

Nitrogen-doped carbon coated Na3V2O2(PO4)2F as a cathode for high-performance sodium-ion batteries

Enhanced cyclability of O3-NaNi0.33Fe0.31Mn0.36O2 by Mg and Cu synergistic doping with strengthened Mn[sbnd]O bonds

Among some practical O3-type layered oxide cathodes, NaNi1/3Fe1/3Mn1/3O2 (NFM) features a high specific capacity and moderate cyclability. However, sluggish Na+ transfer kinetics, low structural stability, and rapid capacity loss during long-term cycling, are still posing a challenge to commercial applications of this material. In this work, we propose a Mg and Cu co-doped O3-type NaMg0.02Cu0.02Ni0.33Fe0.27Mn0.36O2 (MC-NFM) with a stable structure and good cycling stability. It was found that the MnO bonds in MC-NFM are obviously reinforced by synergistic doping with small amounts of Mg and Cu, leading to enhanced structural robustness, decreased Na+ migration barrier, and delayed O3-P3 phase transition. As a result, longer cycle life and enhanced rate performance are achieved. MC-NFM can yield a specific capacity of 142.1 mAh g−1 at 0.1C and 116.0 mAh g−1 at 5C, and maintain 83.6 % of its initial capacity after 400 cycles at 1C. This work provides a promising design of O3-type cathode for sodium-ion batteries.

Multifunctional carbonyl-rich compounds for constructing “corrosion-resistant electrodes and electrolyte interface” in high-voltage sodium-metal batteries

In recent years, there has been notable advancement in the development of high-performance materials for sodium-ion batteries, particularly in layered oxide cathodes. However, research on enhancing the interface between electrolytes and cathodes remains nascent. One promising approach involves the addition of electrolyte additives, recognized for their cost-effectiveness and efficiency in bolstering the electrode/electrolyte interface to enhance material stability during high-voltage cycling. In this work, we investigate the use of glutaric anhydride (GA) as an electrolyte additive to improve the cycling stability of NaNi1/3F1/3M1/3O2/Na (NFM/Na) high-voltage sodium-metal batteries. Batteries using GA-containing electrolytes demonstrate impressive capacity retention: 80.51 % after 200 cycles at 4.0 V and 76.01 % after 150 cycles at 4.1 V. The research delves into the mechanistic insights behind GA’s effectiveness in enhancing cyclic stability. Theoretical calculations reveal that GA plays a crucial role in modifying the structure of the first solvation shells, promoting the formation of an elastic cathode-electrolyte interface (CEI) film enriched with OCO groups. This uniform and stable CEI film effectively preserves the material’s crystal structure and mitigates the dissolution of transition metals, thereby prolonging battery lifespan under demanding extremely cycling conditions.

Achieving complete solid-solution reaction in layered cathodes with reversible oxygen redox for high-stable sodium-ion batteries

Achieving complete solid-solution reaction in layered cathodes with reversible oxygen redox for high-stable sodium-ion batteries

A review of recent progress of self-supported conversion reaction-based anodes for advanced sodium-ion batteries

A review of recent progress of self-supported conversion reaction-based anodes for advanced sodium-ion batteries

Insights into Tiny High‐Entropy Doping Promising Efficient Sodium Storage of Na3V2(PO4)2O2F toward Sodium‐Ion Batteries

AbstractBoth high operation voltage and theoretical capacity promise polyanion‐type fluorophosphate Na3V2(PO4)2O2F as a competitive cathode toward high‐energy‐density sodium‐ion batteries (SIBs). However, the intrinsic low kinetic characteristics seriously influence its high‐power property and service life. To well address this, a creative tiny high‐entropy (HE) doping methodology is purposefully developed to fabricate nanoscale Na3V1.94(Cr, Mn, Co, Ni, Cu)0.06(PO4)3O2F (NVPOF‐HE) as the advanced cathode materials for SIBs. The grain refinement effect induced by collaborative regulations from polyvinyl pyrrolidone and tiny HE heteroatomic doping is reasonably proposed for nanosizing particle dimension of NVPOF‐HE. Systematic experiments and theoretical calculations authenticate that the HE doping efficiently promotes the electronic/ionic transport and high‐voltage capacity contribution, and weakens the lattice expansion over Na+‐(de)intercalation processes. Thanks to the appealing virtues mentioned here, the nano NVPOF‐HE, compared to single‐ion/dual‐ion/triple‐ion doped cases, achieves even better Na+‐storage performance in terms of both high‐rate capacities and long‐term cycling stability. Furthermore, the NVPOF‐HE assembled full SIBs deliver a high materials‐level energy density of 463 Wh kg−1 and electrochemical stability of ≈93.8% capacity retention after 1000 cycles at 5 C rate. More essentially, the fundamental insights gained here provide a significant scientific and technological advancement in high‐performance and durable polyanionic cathodes toward next‐generation SIBs.