Stabilizing fluorine to achieve high-voltage and ultra-stable Na3V2(PO4)2F3 cathode for sodium ion batteries

Deng, Liang; Yu, Fu‐Da; Xia, Yang; Jiang, Yunshan; Sui, Xu–Lei; Zhao, Lei; Meng, Xianghui; Que, Lan‐Fang; Wang, Zhenbo

doi:10.1016/j.nanoen.2020.105659

Cited by 90 publications

(70 citation statements)

References 39 publications

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“…[48] The specific energy density at 0.1 C is up to 423 W h kg −1 with the corresponding mean voltage and C s of 3.74 V and 113 mA h g −1 , respectively, which shows superiority of high-entropy-effect-assisted NVPF-cathode-based SIFCs with higher energy density from raised discharging voltage plateau compared to other relative cathodes (in Figure 5c). [25,26,33,35,36,46] Finally, the long-term cyclic stability of HC//HE-NVPF SIFCs was confirmed, as shown in Figure 5d, the capacity retention can achieve as high as 90.1% after 300 cycles at 1 C. The lighting experiment in the inset of Figure 5d also illustrates the practical application for the as-designed high-entropy effective NVPF-cathode-based SIFBs. Figure 5e shows the GCD curves of the HC//HE-NVPF SIFCs for the 1st, 50th, 100th, 150th, 200th, 250th, and 300th cycles.…”

Section: Resultsmentioning

confidence: 74%

“…The diffraction peaks such as ( 220) and ( 222) undergo a cycle of appearance, disappearance, and reappearance during the dis-/charge process, which means the phase transition occurrence in this region at a low-voltage plateau. [36] However, this phenomenon of HE-NVPF in the same plateau region is completely different, in which, there is no phase transition process at all. This indicates that the high-entropy effect can suppress the occurrence of phase transitions in the low-plateau region, which is consistent with the previous XRD results.…”

Section: Resultsmentioning

confidence: 97%

“…[26,34] In brief, NVPF is still up against two major obstacles, namely poor electronic conductivity and uncontrollable discharging behavior at low voltage region. [35][36][37][38] Building a highly conductive network can certainly improve the electronic conductivity, whereas the excess carbon incorporation will reduce energy density and cost-effectiveness at the same time. So far, there is still lack of effective strategies to regulate rising mean discharging voltage for fixed crystal lattice with the constant active transition-metal center, which is beneficial to achieve tunable voltage region, as well as prolonged discharging interval behavior simultaneously.…”

Section: Introductionmentioning

confidence: 99%

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An Advanced High‐Entropy Fluorophosphate Cathode for Sodium‐Ion Batteries with Increased Working Voltage and Energy Density

et al. 2022

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realization, to further postpone the foreseeable energy crisis in the near future. [1][2][3] Nevertheless, commercially growing demand for LIBs has triggered the cost surge coming from the limited raw materials. [4][5][6] In this regard, cost-effective sodium-ion batteries (SIBs) with bountiful supply and analogous "rocking chair" working mechanism with LIBs, [7][8][9] show promise in becoming one of the favorable alternatives to LIBs, and meet the practical demands of sustainable large-scale energy storage systems as well. [10,11] That is why, SIBs have been extensively studied and flourished over the past decade. However, the existing demerits of poor structural stability, sluggish ion diffusion kinetics, low operating voltage, and unsatisfactory energy/power density of cathode materials remain challenging for the practical application of SIBs. [12][13][14] Toward cathodic hosts for sodium-ion storage, the commonly available materials mainly include layered transition-metal oxides (TMOs) and polyanionic compounds (PACs). Layered transition-metal oxides, Na x /TM/O 2 (TM = Cr, Fe, Co, Mn, Ni, etc.), especially those with a P2 type structure, [15] exhibit better cycle stability and rate performance due to the higher sodium-ion diffusion kinetics, and have been extensively studied. [16] At present, through the use of element doping, substitution, and interface modification suppression, the reversibility of layered transition mental oxide Impossible voltage plateau regulation for the cathode materials with fixed active elemental center is a pressing issue hindering the development of Na-superionic-conductor (NASICON)-type Na 3 V 2 (PO 4 ) 2 F 3 (NVPF) cathodes in sodium-ion batteries (SIBs). Herein, a high-entropy substitution strategy, to alter the detailed crystal structure of NVPF without changing the central active V atom, is pioneeringly utilized, achieving simultaneous electronic conductivity enhancement and diffusion barrier reduction for Na + , according to theoretical calculations. The as-prepared carbon-free highentropy Na 3 V 1.9 (Ca,Mg,Al,Cr,Mn) 0.1 (PO 4 ) 2 F 3 (HE-NVPF) cathode can deliver higher mean voltage of 3.81 V and more advantageous energy density up to 445.5 Wh kg −1 , which is attributed by the diverse transition-metal elemental substitution in high-entropy crystalline. More importantly, high-entropy introduction can help realize disordered rearrangement of Na + at Na(2) active sites, thereby to refrain from unfavorable discharging behaviors at low-voltage region, further lifting up the mean working voltage to realize a full Na-ion storage at the high voltage plateau. Coupling with a hard carbon (HC) anode, HE-NVPF//HC SIB full cells can deliver high specific energy density of 326.8 Wh kg −1 at 5 C with the power density of 2178.9 W kg −1 . This route means the unlikely potential regulation in NASICON-type crystal with unchangeable active center becomes possible, inspiring new ideas on elevating the mean working voltage for SIB cathodes.

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Section: Resultsmentioning

confidence: 74%

Section: Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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An Advanced High‐Entropy Fluorophosphate Cathode for Sodium‐Ion Batteries with Increased Working Voltage and Energy Density

et al. 2022

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“…[45] It is reported that strong ionic F-V bond can enhance the induction of phosphate anion on the electron cloud of each component atom, reducing the energy required for the redox reaction, and thus increasing potentials for fluorine-rich samples. [46][47][48] Above analyses suggest that the proper control of fluorine content in the vanadium fluorophosphate structure is an effective strategy to regulate the calcium storage voltage. In addition, the plot of average discharging voltage versus cycle number at 25 mA g -1 in Figure 3b shows negligible voltage degradation after 250 cycles, demonstrating the voltage stability of the N 1 PVF 3 cathodes cycling in Ca ion cells.…”

Section: Calcium Intercalation Voltage For N 1 Vpf 3 Cathodementioning

confidence: 99%

Ultrastable and High Energy Calcium Rechargeable Batteries Enabled by Calcium Intercalation in a NASICON Cathode

Chen

Shi

Zhang

et al. 2022

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approaching their theoretical energy density ceiling, so there is an urgent need to explore new battery chemistries. [4][5][6][7] Multivalent (Mg 2+ , Ca 2+ , and Al 3+ ) ion batteries are among the top candidates, which utilize more abundant elements. [8][9][10] Multivalent ion batteries also possess competitive energy densities with monovalent ion (Li + , Na + , and K + ) batteries by doubling or tripling the number of electron transfer as intercalation of per charge carrier. Among these options, Ca ion battery (CIB) is considered more appealing due to several fundamental merits. [11][12][13][14] Ca is the fifth most abundant element (4.86 wt.%) in the earth's crust, much less rare than lithium (22 ppm), which would inevitably lower the cost of raw materials for large-scale energy storage applications. The reduction potential of −2.87 V versus standard hydrogen electrode (SHE) for Ca 2+ /Ca is more negative than the −2.36 V versus SHE for Mg 2+ /Mg and −1.68 V versus SHE for Al 3+ /Al, implying higher cell voltages and energy densities. The larger ionic radius of Ca 2+ (1.14 Å) than Mg 2+ (0.84 Å) leads to relatively lower polarization strength for Ca 2+ , suggesting higher Ca 2+ mobility in electrolytes and cathodes. Together with the better safety (i.e., melting points of 842 °C for Ca metal vs 180 °C for Li metal) and insensitive dendrite deposition of high capacity Ca metal (1337 mAh g -1 ), CIBs outstand among the post-LIB technologies.Recent advances in the development of Ca metal and graphite negative electrodes have brought the rechargeable CIB a step closer to a practically feasible battery system. [15][16][17][18][19] Nevertheless, the progress in discovering desirable cathode materials with high capacity, long-cycle life, and high voltage is laborious. Various material groups have been prepared or hypothesized, [20] such as V 2 O 5 , [21][22] Ca x CoO 2 (0.26 ≤ x ≤ 0.50), [23][24] and LiFePO 4 , [25][26] to reversibly store Ca ions as cathodes. Few of them could deliver reasonable cyclic capacities with high working voltages at practically important current densities. The poor electrochemical performance of intercalation cathodes is attributable to the sluggish Ca ion migration kinetics and large volume variations of hosts, stemming from the divalent nature and large size of Ca ions. The divalent Ca 2+ can induce strong electrostatic interactions with the hosts, posing significant energy barriers for effective Ca 2+ migration (e.g., ≈1.7 eV for Ca diffusion in α-V 2 O 5 , [21,27] ≈2 eV for Ca diffusion in Ca x MoO 3 [28] ). Ca-ion batteries (CIBs) have been considered a promising candidate for the next-generation energy storage technology owing to the abundant calcium element and the low reduction potential of Ca 2+ /Ca. However, the large size and divalent nature of Ca 2+ induce significant volume change and sluggish ion mobility in intercalation cathodes, leading to poor reversibly and low energy/power densities for CIBs. Herein, a polyanionic Na superionic conduction (NASICON)-typed Na-vacant Na ...

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“…[8,9] Since the cathode material mainly determines and limits the specific capacity of SIBs in the full-cell configuration, developing high-voltage cathodes is expected to further boost the overall energy density of SIBs. Currently, main cathode materials for SIBs can be categorized into P2 or O3 transition metal oxides, [10,11] polyanionic compounds, [12][13][14][15][16] Prussian blue analogues, [17] and organic compounds, [18][19][20] among others. P2 or O3-structure transition oxides suffer from fast capacity decay during the long-term cycling at high-voltage, [21] while Prussian blue analogues deliver a low coulombic efficiency (CE) and inferior cycle stability due to the coordinated lattice-water.…”

Section: Introductionmentioning

confidence: 99%

Optimizing the Electrolyte Systems for Na₃(VO_1‐xPO₄)₂F_1+2x (0≤x≤1) Cathode and Understanding their Interfacial Chemistries Towards High‐Rate Sodium‐Ion Batteries

Tao

Yang

et al. 2022

ChemSusChem

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Sodium-ion batteries (SIBs) have been regarded as promising alternative to lithium-ion batteries (LIBs) due to the abundance of sodium resource and cost-effectiveness of electrode manufacture. Na 3 (VO 1-x PO 4 ) 2 F 1 + 2x (0 � x � 1, NVPF 1 + 2x ) polyanionic material, a potential high-energy-density cathode, has shown superior electrochemical performances for advanced SIBs due to its high working voltage (> 3.9 V). Electrolyte composition, which plays an indispensable and critical role in determining the cycle stability and the electrode/electrolyte interfacial properties, is of great significance to possess good compatibility with electrode materials, especially the NVPF 1 + 2x cathode. Here, different electrolyte systems, including commonly used 1.0 m NaPF 6 /diglyme (NP-005), 1.0 m NaPF 6 /propylene carbonate (PC)/ 5.0 % fluoroethylene carbonate (FEC) (NP-009), 1.0 m NaClO 4 / ethylene carbonate-dimethyl carbonate (EC-DMC; 1 : 1 v/v)/ 5.0 % FEC (NC-019), and 1.0 m NaClO 4 /PC (NC-013), were systematically investigated and compared for NVPF 1 + 2x cathode. NVPF 1 + 2x electrode with NP-009 electrolyte showed a superior cycle stability and rate capability at 1-10 C (1 C = 130 mA g À 1 ) than that of NC-019 and NC-013, while NVPF 1 + 2x electrode with NP-005 electrolyte showed the best high-rate capability at 20-50 C. The cathode/electrolyte interphase (CEI), post-mortem electrode morphology, and electrochemical kinetic characteristics of NVPF 1 + 2x electrode with different electrolytes were profoundly investigated and compared. It demonstrated that NVPF 1 + 2x electrode with NP-005 exhibited a thin, efficient, and NaF-rich CEI layer with less polarization, smaller interfacial resistance, and faster Na + diffusion than that of NC-019 and NC-013 since they suffered from a thick, overgrown CEI layer due to the consecutive decomposition of FEC, NaClO 4 , and/or linear DMC, resulting in inferior electrochemical performance. This work provides new insights for the battery community to gain more comprehensive understanding about the compatibility and interfacial chemistry between different electrolyte systems and various electrode surfaces.

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Stabilizing fluorine to achieve high-voltage and ultra-stable Na3V2(PO4)2F3 cathode for sodium ion batteries

Cited by 90 publications

References 39 publications

An Advanced High‐Entropy Fluorophosphate Cathode for Sodium‐Ion Batteries with Increased Working Voltage and Energy Density

An Advanced High‐Entropy Fluorophosphate Cathode for Sodium‐Ion Batteries with Increased Working Voltage and Energy Density

Ultrastable and High Energy Calcium Rechargeable Batteries Enabled by Calcium Intercalation in a NASICON Cathode

Optimizing the Electrolyte Systems for Na₃(VO_1‐xPO₄)₂F_1+2x (0≤x≤1) Cathode and Understanding their Interfacial Chemistries Towards High‐Rate Sodium‐Ion Batteries

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Stabilizing fluorine to achieve high-voltage and ultra-stable Na3V2(PO4)2F3 cathode for sodium ion batteries

Cited by 90 publications

References 39 publications

An Advanced High‐Entropy Fluorophosphate Cathode for Sodium‐Ion Batteries with Increased Working Voltage and Energy Density

An Advanced High‐Entropy Fluorophosphate Cathode for Sodium‐Ion Batteries with Increased Working Voltage and Energy Density

Ultrastable and High Energy Calcium Rechargeable Batteries Enabled by Calcium Intercalation in a NASICON Cathode

Optimizing the Electrolyte Systems for Na3(VO1‐xPO4)2F1+2x (0≤x≤1) Cathode and Understanding their Interfacial Chemistries Towards High‐Rate Sodium‐Ion Batteries

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Resources

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Optimizing the Electrolyte Systems for Na₃(VO_1‐xPO₄)₂F_1+2x (0≤x≤1) Cathode and Understanding their Interfacial Chemistries Towards High‐Rate Sodium‐Ion Batteries