An Electrochemical Impedance Study of the Capacity Limitations in Na–O<sub>2</sub> Cells

Knudsen, Kristian B.; Nichols, James Hastings; Vegge, Tejs; Luntz, A. C.; McCloskey, Bryan D.; Hjelm, Johan

doi:10.1021/acs.jpcc.6b02788

Cited by 43 publications

(78 citation statements)

References 28 publications

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“…The GEIS results and SEM images show that the formation of dendrites in Na/O 2 batteries was mostly influenced by the SEI, which is consistent with the literature . Because R CT, Na increased by a factor of 100 through the introduction of oxygen into the system (Figure b and Figure S9a) and visible formation of a grayish passivation film on the sodium electrode was observed (Figure S12b), we assumed that the SEI was mainly formed by oxide species.…”

Section: Resultssupporting

confidence: 89%

“…The insets in Figure a, b illustrate the chosen equivalent circuit model for a two‐electrode measurement of our cell. This is a simplified version of the equivalent circuit model of Knudsen et al., because our focus was on the processes involved at the anode. In comparison with the galvanostatic shallow cycling in Figure , two glass fiber separators were used instead of one to significantly increase the distance between the anode and cathode and ensure that the charging of the cell was not influenced by short circuits in the first two cycles …”

Section: Resultsmentioning

confidence: 99%

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Incorporating Diamondoids as Electrolyte Additive in the Sodium Metal Anode to Mitigate Dendrite Growth

et al. 2020

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Owing to the high abundance and gravimetric capacity (1165.78 mAh g−1) of pure sodium, it is considered as a promising candidate for the anode of next‐generation batteries. However, one major challenge needs to be solved before commercializing the sodium metal anode: The growth of dendrites during metal plating. One possibility to address this challenge is to use additives in the electrolyte to form a protective solid electrolyte interphase on the anode surface. In this work, we introduce a diamondoid‐based additive, which is incorporated into the anode to target this problem. Combining operando and ex situ experiments (electrochemical impedance spectroscopy, optical characterization, and cycling experiments), we show that molecular diamondoids are incorporated into the anode during cycling and successfully mitigate the growth of dendrites. Furthermore, we demonstrate the positive effect of the additive on the operation of sodium‐oxygen batteries by means of increased energy density.

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Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Incorporating Diamondoids as Electrolyte Additive in the Sodium Metal Anode to Mitigate Dendrite Growth

et al. 2020

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“…The discharge voltage is 2.09 V and it is slightly lower than that in the GC cell. Moreover, the charging plateau stays at 2.31 V followed by a dramatic increase up to the limiting voltage of 4.0 V.[3a,8] The low charging voltage shows that the decomposition of the discharge product only contributes little overpotential to the charging process, which is a result from a kinetically favorable process . The voltage increase at the end of charge implies the depletion of the rechargeable product.…”

Section: Resultsmentioning

confidence: 99%

Sodium Peroxide Dihydrate or Sodium Superoxide: The Importance of the Cell Configuration for Sodium–Oxygen Batteries

Wang

et al. 2017

Small Methods

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In sodium–oxygen (Na–O2) batteries, multiple discharge products have been observed by different research groups. Given the fact that different materials, gas supplies, and cell configurations are used by different groups, it is a great challenge to draw a clear conclusion on the formation of the different products. Here, two different cell setups are used to investigate the cell chemistries of Na–O2 batteries. With the same materials and gas supplies, a peroxide‐based product is observed in a glass chamber cell and a superoxide‐based product is observed in a stainless‐steel cell. Ex situ high‐energy X‐ray diffraction (HEXRD) and Raman spectroscopy are performed to investigate the structure and composition of the product. In addition, in situ XRD is used to investigate the structure evolution of the peroxide‐based product. The findings highlight the importance of the cell design and emphasize the critical environment of the formation of the discharge products of Na–O2 batteries.

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“…We scrutinized the electrochemical charging responses of sodium–oxygen batteries with systematic variations of storage times after discharge to confirm the chemical stability of sodium superoxide in electrolytes for sodium–oxygen batteries. The applied current and discharge capacity in the present study were set to 0.1 mA and 0.25 mAh, respectively, with a cut‐off voltage of 3.0 V (vs Na/Na + ) . The storage time was controlled from 6 to 24 h after discharge.…”

Section: Resultsmentioning

confidence: 99%

Highly Durable and Stable Sodium Superoxide in Concentrated Electrolytes for Sodium–Oxygen Batteries

Park

Lee

Park

et al. 2018

Advanced Energy Materials

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great attention because they exhibit the highest theoretical energy density (≈1100 Wh kg −1 based on NaO 2 as a discharge product) among available sodium rechargeable battery chemistries while also offering the advantages of elemental earth abundance and potential cost efficiency. [1] In particular, their intrinsically high energy efficiency and reversibility make sodium-oxygen batteries strong candidates for next-generation rechargeable batteries. [1,2] Unlike lithium-oxygen batteries, for which a peroxide phase is commonly formed as the main discharge product rather than a superoxide phase, [3] the thermodynamic stability of sodium superoxide and its facile dissociation enable its reversible formation as a main product in sodium-oxygen batteries. [1,2,[4][5][6][7] The promising electrochemical properties of sodium-oxygen batteries have been attributed to the formation of sodium superoxide, which exhibits substantial solubility in electrolytes and thus drives solution-based reactions as a dominant pathway. The finding of a proton as a phase-transfer catalyst [8] and the critical role of electrolyte solvation in the discharge process [9] also strongly support the dominant solution reaction mechanisms in sodium-oxygen batteries, which have been confirmed by experimental evidence of soluble superoxide species [7,10,11] and the low solvation energy of the sodium superoxide estimated in a previous computational study. [12] These intrinsic solution chemistries enable the achievement of high capacity and low polarization for sodium-oxygen batteries without the need for redox mediators or soluble catalysts, which are believed to be necessary for the development of highly reversible lithiumoxygen [13][14][15][16][17][18][19] or lithium-gas (SO 2 , CO 2 …) [20][21][22] batteries.Despite the thermodynamic stability of sodium superoxide in sodium-oxygen batteries, recent studies have reported the chemical instability of sodium superoxide in ether-based electrolytes, in which undesirable self-decomposition occurs. In our previous study, time-resolved characterizations revealed that sodium superoxide transforms into byproducts, mainly sodium peroxide dihydrate (Na 2 O 2 ·2H 2 O), within 12 h of exposure to diethylene glycol dimethyl ether (DEGDME) electrolytes; we proposed the idea that the side reactions were triggered by spontaneous dissolution of sodium superoxide and subsequent Rechargeable sodium-oxygen batteries have attracted considerable interest as promising candidates for next-generation batteries owing to their large energy density, high energy efficiency, and potential cost-effectiveness. The intrinsic stability of the discharge product, sodium superoxide, results in highly reversible solution-based electrochemistry in sodium-oxygen batteries, leading to their higher energy efficiency and reversibility compared with their lithium counterparts. However, recent studies have shown that extended storage of sodium superoxide in ethereal electrolytes induces dissolution of the sodium superoxide and undesirable chemical ...

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An Electrochemical Impedance Study of the Capacity Limitations in Na–O₂ Cells

Cited by 43 publications

References 28 publications

Incorporating Diamondoids as Electrolyte Additive in the Sodium Metal Anode to Mitigate Dendrite Growth

Incorporating Diamondoids as Electrolyte Additive in the Sodium Metal Anode to Mitigate Dendrite Growth

Sodium Peroxide Dihydrate or Sodium Superoxide: The Importance of the Cell Configuration for Sodium–Oxygen Batteries

Highly Durable and Stable Sodium Superoxide in Concentrated Electrolytes for Sodium–Oxygen Batteries

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An Electrochemical Impedance Study of the Capacity Limitations in Na–O2 Cells

Cited by 43 publications

References 28 publications

Incorporating Diamondoids as Electrolyte Additive in the Sodium Metal Anode to Mitigate Dendrite Growth

Incorporating Diamondoids as Electrolyte Additive in the Sodium Metal Anode to Mitigate Dendrite Growth

Sodium Peroxide Dihydrate or Sodium Superoxide: The Importance of the Cell Configuration for Sodium–Oxygen Batteries

Highly Durable and Stable Sodium Superoxide in Concentrated Electrolytes for Sodium–Oxygen Batteries

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An Electrochemical Impedance Study of the Capacity Limitations in Na–O₂ Cells