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

Abstract

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.

Solid Electrolyte Interphases on Sodium Metal Anodes

“…Hence, the precursor concentration and reaction time should be precisely tuned to achieve ideal protection. Recently, various Na 3 PS 4 (NaPS) protective layers were fabricated by controlling the experimental design parameters, as illustrated in Ether-based electrolytes 1 m NaPF 6 in diglyme -0.5 mA cm −2 ; 1 mA h cm −2 99.9%/300 cycles 2015 [64] 0.5% NaFSI in DME -0.2 mA cm −2 ; 0.5 mA h cm −2 97.7%/250 cycles 2017 [73] 0.5 m NaBF 4 in diglyme -0.5 mA cm −2 ; 1 mA h cm −2 99.93%/400 cycles 2020 [67] 1 m NaBF 4 in TEGDME -0.5 mA cm −2 ; 0.5 mA h cm −2 99.9%/1000 cycles 2020 [70] 0.1 m NaBPh 4 in DME -0.5 mA cm −2 ; 0.5 mA h cm −2 99.85%/300 cycles 2019 [43] Additives 1 m NaClO 4 in EC/PC/FEC 5 wt% FEC 1 mA cm −2 ; 1 mA h cm −2 100 h 2018 [56] 1 m NaPF 6 in DME/FEC/TMP 40 vol% HFPM 1 mA cm −2 ; 1 mA h cm −2 800 h 2019 [86] 2 m NaTFSI in TMP/FEC 30 vol% FEC 0.3 mA cm −2 ; 0.3 mA h cm −2 1000 h 2019 [85] 1 m NaPF 6 in diglyme/Na 2 S 6 0.033 m Na 2 S 6 10 mA cm −2 ; 5 mA h cm −2 100 h 2018 [87] 1 m NaTFSI in FEC/NaAsF 6 0.75 wt% NaAsF 6 0.1 mA cm −2 ; 0.5 mA h cm −2 97%/400 cycles 2019 [95] 1 m NaClO 4 in EC/DEC/SnCl 2 50 × 10 −3 m SnCl 2 0.5 mA cm −2 ; 1 mA h cm −2 500 h 2019 [96] 4 m NaFSI in DME/SbF 3 1% SbF 3 0.5 mA cm −2 ; 0.5 mA h cm −2 1000 h 2020 [210] 0.8 m LiPF 6 , 1 m NaPF 6 in DME 0.8 m LiPF 6 0.2 mA cm −2 ; 0.2 mA h cm −2 99.2%/100 cycles 2018 [93] 1 m NaOTf in TEGDME/KTFSI 0.01 m KTFSI 0.5 mA cm −2 ; 1 mA h cm −2 99.5%/300 cycles 2018 [94] 0.5 m NaOTf in diglyme/DCAD 1.0 mg mL −1 DCAD 0.356 mA cm −2 ; 0.2 mA h cm −2 100 cycles 2020 [211] Concentration effects 4 m NaFSI in DME -1 mA cm −2 ; 1 mA h cm −2 99%/300 cycles 2016 [71] 2.5 m NaCF 3 SO 3 in diglyme -2 mA cm −2 ; 1 mA h cm −2 100 h 2019 [102] 5 m NaFSI in DME -0.0028 mA cm −2 ; 0.0014 mA h cm −2 600 h 2017 [103] 2.1 m NaFSI in DME/BTFE -1 mA cm −2 ; 1 mA h cm −2 98.95%/400 cycles 2018 [108] Ionic liquids Buffered Na-Cl-IL -0.5 mA cm −2 ; 0.25 mA h cm −2 95%/100 cycles 2019 [60] NaAlCl 4 • 2SO 2 -0.75 mA cm −2 ; 1.5 mA h cm −2 95 cycles 2015 [135] NaBF 4 -2.5NH 3 -10 mA cm −2 ; -100 cycles 2017 [138] a) Reproduced with permission. [139] Copyright 2019, Wiley.…”

Interfacial Effects in Lithium and Sodium Batteries

“…[ 35 ] Grain boundaries were found to be prone to cracking in materials such as LiNi 0.8 Co 0.15 Al 0.05 O 2 ; [ 36 ] by synthesizing the related material LiNi 0.5 Mn 0.3 Co 0.2 O 2 as isolated grains rather than agglomerates, cracking was largely avoided [ 37 ] and improved cycling stability was observed. [ 38 ] To mitigate dendrite growth, diamond‐like nanoparticles were reported to be an effective electrolyte additive in both lithium [ 39 ] and sodium [ 40 ] metal systems.…”

Alternative anodes for Na–O2 batteries: the case of the Sn4P3 alloy

“…The preferred negative electrode in this type of device is metallic sodium, 18 due to its high abundance and high gravimetric capacity (1166 mA h g À1 ). 8 Despite its great potential, the use of metallic sodium as the negative electrode presents some drawbacks: 19 (1) inhomogeneous plating/ stripping process during discharge (sodium ions are released)/ charge (sodium ions are deposited on the surface of the anode), (2) the formation of dendrites, which leads to internal short-circuits and poor cycling, 20,21 and (3) the reactivity between Na + and the electrolyte which leads to the consumption of both, leading to the appearance of side products on the surface of the anode. Thus, these products increase the impedance of the anode/electrolyte interface and limit the cycling capability to tens of cycles.…”