Sb–C nanofibers with long cycle life as an anode material for high-performance sodium-ion batteries

Seo

et al. 2015

Energy Environ. Sci.

336

256

Battery chemistry based on earth-abundant elements has great potential for the development of cost-effective, large-scale energy storage systems. Herein, we report, for the first time, that maricite NaFePO 4 can function as an excellent cathode material for Na ion batteries, an unexpected result since it has been regarded as an electrochemically inactive electrode for rechargeable batteries. Our investigation of the Na re-(de)intercalation mechanism reveals that all Na ions can be deintercalated from the nano-sized maricite NaFePO 4 with simultaneous transformation into amorphous FePO 4 . Our quantum mechanics calculations show that the underlying reason for the remarkable electrochemical activity of NaFePO 4 is the significantly enhanced Na mobility in the transformed phase, which is $one fourth of the hopping activation barrier. Maricite NaFePO 4 , fully sodiated amorphous FePO 4 , delivered a capacity of 142 mA h g À1 (92% of the theoretical value) at the first cycle, and showed outstanding cyclability with a negligible capacity fade after 200 cycles (95% retention of the initial cycle).The demand for large-scale energy storage systems (EESs) has prompted considerable effort in the development of new types of batteries with cost-effective and sustainable properties. While the high cost of current Li ion batteries (LIBs) remains one of the major hurdles towards large-scale energy storage applications, 1-12 battery chemistry based on earth-abundant elements offers a feasible solution. Recently, Na ion batteries (NIBs) have been considered as a promising alternative to LIBs since the underlying electrochemical reaction is similar to that of LIBs, but is based on the unlimited resources of Na from seawater. [13][14][15][16][17][18][19][20] The use of redox chemistry using earth abundant transition metals would provide the optimal combination with Na electrochemistry further highlighting the advantage of NIBs.In recent years, considerable research has been carried out on Fe-based electrode materials for use in NIBs. Broader contextWe report, for the rst time, that maricite NaFePO 4 can function as an excellent cathode material for Na ion batteries, an unexpected result since it has been regarded as an electrochemically inactive electrode for rechargeable batteries. Our investigation of the Na re-(de)intercalation mechanism reveals that all Na ions can be deintercalated from the nanosized maricite NaFePO 4 with simultaneous transformation into amorphous FePO 4 . Our quantum mechanics calculations show that the underlying reason for the remarkable electrochemical activity of NaFePO 4 is the signicantly enhanced Na mobility in the transformed phase, which is $one fourth of the hopping activation barrier. Maricite NaFePO 4 , fully sodiated amorphous FePO 4 , delivered a capacity of 142 mA h g À1 (92% of the theoretical value) at the rst cycle, and showed outstanding cyclability with a negligible capacity fade aer 200 cycles (95% retention of the initial cycle).540 | Energy Environ. Sci., 2015, 8, 540-545This jour...

Section: Ev)mentioning

confidence: 99%

Unexpected discovery of low-cost maricite NaFePO₄as a high-performance electrode for Na-ion batteries

Seo

et al. 2015

Energy Environ. Sci.

336

256

“…Co-intercalation between graphite and diglymebased electrolyte could also achieve a relatively high capacity of B90 mA h g À 1 and long cycle life 15 . Recent findings have shown that the anode materials for SIBs based on alloy-type (for example, metallic and intermetallic materials [16][17][18][19] ) and conversion-type (for example, sulfides [20][21][22][23] ) exhibited high initial capacity, but suffered from poor cyclability most likely due to the large volume change and the sluggish kinetics. In addition, organic anode materials (for example, Na 2 C 8 H 4 O 4 ) and carboxylate-based materials have been investigated as anode materials for SIBs 24,25 , but the electronic conductivity and cyclability still remain the significant challenge.…”

mentioning

confidence: 99%

Na+ intercalation pseudocapacitance in graphene-coupled titanium oxide enabling ultra-fast sodium storage and long-term cycling

et al. 2015

Sodium-ion batteries are emerging as a highly promising technology for large-scale energy storage applications. However, it remains a significant challenge to develop an anode with superior long-term cycling stability and high-rate capability. Here we demonstrate that the Na þ intercalation pseudocapacitance in TiO 2 /graphene nanocomposites enables high-rate capability and long cycle life in a sodium-ion battery. This hybrid electrode exhibits a specific capacity of above 90 mA h g -1 at 12,000 mA g -1 (B36 C). The capacity is highly reversible for more than 4,000 cycles, the longest demonstrated cyclability to date. First-principle calculations demonstrate that the intimate integration of graphene with TiO 2 reduces the diffusion energy barrier, thus enhancing the Na þ intercalation pseudocapacitive process. The Na-ion intercalation pseudocapacitance enabled by tailor-deigned nanostructures represents a promising strategy for developing electrode materials with high power density and long cycle life.

“…[4][5][6] However, particularly regarding the anode side, the identification of long-term stable, environmentally friendly, and abundant active materials, providing high specific capacities and operating at a reasonably low potential, is still considered to be one of the major challenges for this technology. 4,6,7 So far, research activities basically focused on hard carbons, [8][9][10][11][12][13][14] organic compounds like sodium terephthalate or carboxylates, [15][16][17][18] alloying materials such as Sn, [19][20][21][22][23][24][25][26][27] Sb, 28,29 or Ge, 30 conversion materials, [31][32][33][34] or titanium-based insertion materials like Na 2 Ti 3 O 7 [35][36][37] or Li 4 Ti 5 O 12. 38 Generally, insertion materials offer substantial advantages compared to alloying or conversion materials with respect to safety issues, long-term cycling stability, and frequently also environmental friendliness as well as natural abundance.…”

mentioning

confidence: 99%

Nanocrystalline TiO₂(B) as Anode Material for Sodium-Ion Batteries

Wu¹,

Bresser²,

Buchholz³

et al. 2014

J. Electrochem. Soc.

111

High surface area, nanostructured, and phase-pure TiO 2 (B) noodles-like secondary particles were successfully synthesized by a facile one-pot synthesis, based on the hydrolysis of TiCl 3 using a mixture of ethylene glycol and water at moderate temperature. The primary nanoparticles have a uniform size and are about 15 nm in diameter as determined by TEM analysis and exhibit an increased exposure of the (010) facet as indicated by XRD analysis. Unlike the electrochemical reaction with lithium, the application as sodiumion electrode material reveals substantial differences, including the initial amorphization of the TiO 2 (B) particles, accompanied by a partial irreversibility of the sodium storage, presumably related to sodium trapping inside the active material particles and the absence of a stable solid electrolyte interphase, as indicated by galvanostatic cycling and electrochemical impedance spectroscopy, respectively. Besides, TiO 2 (B)-based electrodes show a stabilized reversible capacity of about 100 mAh g −1 and a very good C rate capability. While sodium-ion batteries were initially considered only as lowcost alternative for lithium-ion batteries with a particular focus on their application as stationary energy storage devices, 1-3 recent developments indicated that such devices might provide even similar energy densities in case suitable cathode and anode active materials are combined. [4][5][6] However, particularly regarding the anode side, the identification of long-term stable, environmentally friendly, and abundant active materials, providing high specific capacities and operating at a reasonably low potential, is still considered to be one of the major challenges for this technology. 4,6,7 47 Among these, the best results in terms of specific capacity, long-term cycling stability, and high rate capability were certainly reported for anatase TiO 2 . [40][41][42][43] However, the reversible sodium storage mechanism is obviously different from the classic (de-)insertion mechanism known for lithium, [48][49][50][51][52][53] as an initial reduction of TiO 2 to metallic titanium and an amorphous sodium titanate occurs. 42 TiO 2 (B) is a very well performing anode material for lithium-ion applications, 54-60 but so far -to the best of our knowledge -only one study reported its application as sodium-ion active material. The electrochemical performance, which might be best described by a rather rapid initial capacity fading and a low reversible capacity of about 50 mAh g −1 , is certainly not that promising, 47 although this might be also related to the cut-off potentials of 3.0 and 0.8 V vs. Na/Na + . Besides, the authors observed a rather huge expansion of the (001) 3+ and Ti 4+ at the nanotubes surface, while the general morphology of the tubes remained after sodiation. Consequently, a solid solution mechanism for the reversible sodium ion (de-)insertion comparable to the lithium ion storage mechanism was proposed.Herein, however, we show that TiO 2 (B) -similarly to anatase TiO 2 -presents a rath...