Tailoring a New 4V‐Class Cathode Material for Na‐Ion Batteries

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potential (E° = −2.71 V vs standard hydrogen electrode (SHE) for Na + /Na, 0.3 V higher than that of Li + /Li).[5] Thus, rechargeable batteries based on sodium electrochemistry are considered as promising alternatives for grid-scale EES applications, which put specific requirements on the cost and sustainable resource supply of the battery. The component parts and the working principle for sodium-ion batteries (SIBs) are quite similar to those of LIBs, as shown in Figure 1. [6] Na + ions migrate between a positive electrode (cathode) and a negative electrode (anode) through an Na + electrolyte in between. Both electrodes are composed of intercalation compounds that allow reversible insertion and extraction of Na + ions. [7] Studies on Na + ions intercalation chemistry can be traced back to 1980s, [8] yet they did not attract much attention due to the LIBs, which held significant advantages in energy output and electrochemical stability over other rechargeable batteries and dominated the research/market for the next two decades. With the concern of potential shortage of Li resources, some concerted effort began to revisit the SIB technology and its key materials, especially after the year 2010. Al foil can be used as current collectors for the anode rather than Cu in SIBs because Na does not alloy with Al, which may help to further reduce the cost and increase the energy density. [9] Besides the cost advantages, SIBs also offer opportunities to obtain a faster kinetics with the electrochemical reaction; for example, it may enable a high Na + conductivity in bulk solid within a wide temperature range [10] and an easier charge transfer owing to less pronounced solvation. Such merits, according to the recent work, have led to surprisingly low polarization and high-rate capability (e.g., in Na 3 V 2 (PO 4 ) cathode materials), [11] making SIBs quite appealing for high-power applications. [12] Although SIBs present a less expensive raw materials compared with LIBs, it is worth noting that the higher energynormalized cost of prototype SIBs [13] demonstrates the importance to improve its energy density, which can be realized by increasing the output voltage or capacity. Given that the output voltage of an SIB is determined by the electrode potential difference between the positive and the negative electrodes and the positive electrode is the bottleneck for boosting the energy output of SIBs, major efforts have been devoted to develop advanced cathode materials with high output voltage and high capacity. [14] Prominent potential cathode candidates including Room-temperature rechargeable sodium-ion batteries are considered as a promising alternative technology for grid and other storage applications due to their competitive cost benefit and sustainable resource supply, triumphing other battery systems on the market. To facilitate the practical realization of the sodium-ion technology, the energy density of sodium-ion batteries needs to be boosted to the level of current commercial Li-ion batteries. An effective approach...

Section: High-voltage Polyanion Positive Electrode Materials Based Onmentioning

confidence: 99%

Progress in High‐Voltage Cathode Materials for Rechargeable Sodium‐Ion Batteries

You

Manthiram

2017

448

268

“…[ 205 ] More recently, Kim et al reported a new V-based pyrophosphate compound, Na 4 V 3 (P 2 O 7 ) 4 , as a cathode for NIBs. [ 207 ] The electrode delivered a capacity of approximately 80 mA h g −1 at a current rate of C/10 with an average voltage of 4.13 V vs Na + /Na. The electrode exhibited the highest V 3+ /V 4+ redox potential among all the V-based polyanionic compounds, which is attributed to the unique structural aspect of VO 6 octahedra sharing every corner with a P 2 O 7 group, maximizing the inductive effect in the structure.…”

Section: (14 Of 38)mentioning

confidence: 99%

“…[205][206][207] Barpanda et al fi rst introduced tetragonal Na 2 (VO)P 2 O 7 , which yields a reversible capacity of 80 mA h g −1 involving the V 4+ /V 5+ redox reaction at 3.8 V vs Na + /Na. [ 205 ] More recently, Kim et al reported a new V-based pyrophosphate compound, Na 4 V 3 (P 2 O 7 ) 4 , as a cathode for NIBs.…”

Section: (14 Of 38)mentioning

confidence: 99%

Recent Progress in Electrode Materials for Sodium‐Ion Batteries

Kim

Zhang

et al. 2016

Self Cite

884

595

Grid‐scale energy storage systems (ESSs) that can connect to sustainable energy resources have received great attention in an effort to satisfy ever‐growing energy demands. Although recent advances in Li‐ion battery (LIB) technology have increased the energy density to a level applicable to grid‐scale ESSs, the high cost of Li and transition metals have led to a search for lower‐cost battery system alternatives. Based on the abundance and accessibility of Na and its similar electrochemistry to the well‐established LIB technology, Na‐ion batteries (NIBs) have attracted significant attention as an ideal candidate for grid‐scale ESSs. Since research on NIB chemistry resurged in 2010, various positive and negative electrode materials have been synthesized and evaluated for NIBs. Nonetheless, studies on NIB chemistry are still in their infancy compared with LIB technology, and further improvements are required in terms of energy, power density, and electrochemical stability for commercialization. Most recent progress on electrode materials for NIBs, including the discovery of new electrode materials and their Na storage mechanisms, is briefly reviewed. In addition, efforts to enhance the electrochemical properties of NIB electrode materials as well as the challenges and perspectives involving these materials are discussed.

“…By far, various cathode materials including layered transition-metal oxides, Prussian blue analogues (PBAs), and polyanion-type compounds have been proposed. [11][12][13] Recently, the Na superionic conductor (NASICON)-structured polyanion-type materials are of significant interest because of their unique crystal framework that is constructed by units of MO 6 octahedrons (M represents transition metals) and XO 4 tetrahedrons (X = P, S, Si, As), building 3D ion channels for fast Na + migration. [5][6][7] On the other hand, the applications of PBAs are limited by their low volume density, inferior thermal stability, and toxicity of cyanide.…”

mentioning

confidence: 99%

Rational Architecture Design Enables Superior Na Storage in Greener NASICON‐Na₄MnV(PO₄)₃ Cathode

Jin

Chen

et al. 2018

173

123

has been made to explore suitable cathode materials, which are expected to have high capacity, high potential, stable lattice framework, and fast sodium-ion diffusivity. By far, various cathode materials including layered transition-metal oxides, Prussian blue analogues (PBAs), and polyanion-type compounds have been proposed. Although the layered transition-metal oxide materials normally exhibit high theoretical capacity, they suffer from structural instability and unsatisfactory cycle-life. [5][6][7] On the other hand, the applications of PBAs are limited by their low volume density, inferior thermal stability, and toxicity of cyanide. [8][9][10] In this context, great attention has been paid on the polyanion-type materials due to their robust crystal framework with high-level thermal stability, and the moderate capacity with tunable high redox potential, which can achieve high energy density. [11][12][13] Recently, the Na superionic conductor (NASICON)-structured polyanion-type materials are of significant interest because of their unique crystal framework that is constructed by units of MO 6 octahedrons (M represents transition metals) and XO 4 tetrahedrons (X = P, S, Si, As), building 3D ion channels for fast Na + migration. [14][15][16][17][18] Among diverse NASICON-structured compounds, Na 3 V 2 (PO 4 ) 3 is a hotspot, which can deliver a highly reversible capacity over 110 mAh g −1 , and an energy density of over 370 Wh kg −1 as a result of a flat voltage plateau located at 3.3-3.4 V. [19] Although massive work has been reported to promote the development of Na 3 V 2 (PO 4 ) 3 by nanosizing and/or optimizing its poor electronic conductivity, [20][21][22][23] in order to meet the demand of practical applications of Na 3 V 2 (PO 4 ) 3 , improving its operating voltage to reach a higher energy density is urgent. In this regard, researchers have focused on ion-doping strategy to partially substitute V with other elements. Lavela and co-workers used Cr to replace 10% of V and the as-synthesized Na 3 V 1.8 Cr 0.2 (PO 4 ) 3 showed a short plateau above 3.8 V. [24] This high-potential plateau can be prolonged by increasing the amount of Cr to 50%, forming a new material Na 3 VCr(PO 4 ) 3 , which has been reported by Yang and co-workers. [25] In addition, introducing F into Na 3 V 2 (PO 4 ) 3 has been proven effective and the resulting Na 3 V 2 (PO 4 ) 2 F 3 could exhibit an average potential at 3.7-3.8 V, [26][27][28][29] apparently surpassing Na 3 V 2 (PO 4 ) 3 . However, both Cr and F are too expensive and environmentally hazardous to scale-up Na 3 V 2 (PO 4 ) 3 has attracted great attention due to its high energy density and stable structure. However, in order to boost its application, the discharge potential of 3.3-3.4 V (vs Na + /Na) still needs to be improved and substitution of vanadium with other lower cost and earth-abundant active redox elements is imperative. Therefore, the Na superionic conductor (NASICON)structured Na 4 MnV(PO 4 ) 3 seems to be more attractive due to its lower toxicity and higher volt...