Effect of Anion Species in Early Stage of SEI Formation Process

Sonoki, Hidetoshi; Matsui, Masaki; Imanishi, Nobuyuki

doi:10.1149/2.0191915jes

Cited by 40 publications

(35 citation statements)

References 52 publications

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“…were found able to generate LiF‐rich SEI and could successfully suppress Li dendrite growth. [ 12,33,52 ] To further probe the underlying cause of the drastically enhanced Li electrodeposition performance observed in our fluorinated FB‐SPE over conventional non‐fluorinated SPE, the presence of LiF interaction in the SPE systems was studied via FT‐IR as well as 19 F NMR. To better show the change of peak shift and shape, the LiF interactions of small molecular components of FB‐SPE, which were the HFBMA and PEGMA monomers, were also examined in parallel.…”

Section: Resultsmentioning

confidence: 99%

Fluorinated Bifunctional Solid Polymer Electrolyte Synthesized under Visible Light for Stable Lithium Deposition and Dendrite‐Free All‐Solid‐State Batteries

Jia

Wen

Wang

et al. 2021

Adv Funct Materials

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Solid polymer electrolytes (SPEs) that can offer flexible processability, highly tunable chemical functionality, and cost effectiveness are regarded as attractive alternatives for liquid electrolytes (LE) to address their safety and energy density limitations. However, it remains a great challenge for SPEs to stabilize Li+ deposition at the electrolyte–electrode interface and impede lithium dendrite proliferation compared with LE‐based systems. Herein, a design of solid‐state fluorinated bifunctional SPE (FB‐SPE) that covalently tethers fluorinated chains with polyether‐based segments is proposed and synthesized via photo‐controlled radical polymerization (photo‐CRP). In contrast to the conventional non‐fluorinated polyether‐derived SPEs, FB‐SPE is able to provide conducting Li+ transport pathways up to ≈5.0 V, while simultaneously forming a LiF interaction that can enhance Li anode compatibility and prevent Li dendrites growth. As a result, the FB‐SPE exhibits outstanding cycling stability in Li||Li symmetrical cells of over 1500 operating hours at as high current density as 0.2 mA cm−2. A thin and uniform Li deposition layer and LiF‐rich SEI at the surface of Li anode are found, and stable cycling with average coulombic efficiencies of 99% is demonstrated in Li||LFP and Li||NCM all‐solid‐state batteries based on such bifunctional fluorinated SPEs. The interesting fluorine effect and effective self‐suppression of lithium dendrites will inform rational molecular design of novel electrolytes and practical development of all‐solid‐state Li metal batteries.

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Section: Resultsmentioning

confidence: 99%

Fluorinated Bifunctional Solid Polymer Electrolyte Synthesized under Visible Light for Stable Lithium Deposition and Dendrite‐Free All‐Solid‐State Batteries

Jia

Wen

Wang

et al. 2021

Adv Funct Materials

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“…For example, it can form via the decomposition of salt such as LiPF 6 30,34,45,75,108 and LiTFSI, 1,75,76,108 additives such as fluoroethylene carbonate, 1,109,110 or via reactions involving trace HF. 37,42,77,111−113 LiF can also be formed from the chemical reaction of SEI components with HF, 34,77 114 ), which are components that provide the baseline for most commercially utilized electrolytes.…”

Section: ■ Introductionmentioning

confidence: 99%

“…(1) Direct electrochemical reduction of fluorinated salt anions, such as PF 6 − and AsF 6 − : 30,34,45,75,108,115 Li + + PF Reaction 1, in which the F-source in LiF is PF 6 − , is predicted from quantum chemistry (QC) calculations to occur below 1.5− 1.6 V vs Li/Li +75,109,115 (the exact voltage depends in the anions immediate environment, as shall be discussed below) with the reaction barrier decreasing with decreasing graphite electrode potential. 115 Peaks in CVs of LiPF 6 in carbonates solutions at about this voltage range have been found experimentally on metal, semiconductor, and carbon surfaces (see e.g., refs 17, 30, 36, 37, 40, 41, 45, 48, 49, 51, 74, 109, 119).…”

Section: ■ Introductionmentioning

confidence: 99%

“…Of particular interest were the decomposition voltages (i.e., stability windows) and nature of passivation films in terms of chemical composition and physical structure. The techniques utilized included atomic force microscopy (AFM), ,, infrared spectroscopies, − electrochemical impedance spectroscopy, ,− electrochemical quartz crystal microbalance, , X-ray photoelectron spectroscopy (XPS), − ,,,,,− secondary ion mass spectroscopy (SIMS), ,, grazing incidence X-ray scattering, and X-ray reflectivity (XRR) …”

Section: Introductionmentioning

confidence: 99%

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Toward Unraveling the Origin of Lithium Fluoride in the Solid Electrolyte Interphase

et al. 2021

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The solid electrolyte interphase (SEI) is an integral part of Li-ion batteries and their performance, representing the key enabler for reversibility and also serving as a major source of capacity loss and dictating the cell kinetics. In the pervasive LiPF6-containing electrolytes, LiF is one of the SEI’s major components; however, its formation mechanism remains unclear. Electrochemically, two separate reduction pathways could lead to LiF, either via direct anion reduction or electrocatalytic transformation of HF. This work aims to shed light on understanding the role played by these pathways. In a multimodal experimental and theoretical approach, we carried out operando structural characterization on an inert model single crystalline N-doped SiC working electrode during voltammetric scans in LiPF6 baseline electrolytes and complemented these with ex situ chemical characterization. These results were supplemented by cyclic voltammetry measurements using a variety of electrolyte formulations under different cycling rates as well as quantum chemical calculations and Born–Oppenheimer molecular dynamics simulations. Our results reveal that the reductive formation of LiF in these systems is likely a combined mechanism, which concomitantly involves both direct anion reduction and electrocatalytic transformation of HF. Specifically, LiF nucleates via the electrocatalytic transformation of HF followed by significant anion reduction.

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“…[117] Fabricating an artificial SEI on the surface of Li metal is widely considered due to its great effectiveness to dramatically improve the reversibility of working Li metal anode. [118][119][120] Profiting from the boomingly developed nanotechnologies, various nanoscale artificial SEIs with tunable functions can be achieved. Both in situ regulation and ex situ incorporation are efficient strategies to fulfill nanoartificial SEIs.…”

Section: Nano-artificial Seismentioning

confidence: 99%

Review on nanomaterials for next‐generation batteries with lithium metal anodes

Ding

Yan

et al. 2020

Nano Select

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Stable lithium (Li) metal anode is highly pursued to accelerate the development of high-energy-density battery systems. In this article, the stable Li metal batteries boosted by nano-technology and nano-materials are comprehensively reviewed. Two emerging strategies, including nanostructured lithium metal frameworks and nano-artificial solid-electrolyte interphase (SEI) are particularly focused. First, typical conductive/non-conductive nanostructured frameworks and the corresponding merits are introduced. The physical and chemical modifications of the traditional nano-frameworks are further summarized. In addition, the nano-artificial SEIs built by in situ regulation and ex situ fabrication strategies are involved, with the scientific and technologic issues concerned on the interface well discussed. This review mainly focuses on the fresh benefits brought by nano-technology and nano-materials on building better lithium metal batteries. The recent advances of nanostructured lithium metal frameworks and nanoscale artificial SEIs are concluded, and the challenges as well as promising directions for future research are prospected.

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Effect of Anion Species in Early Stage of SEI Formation Process

Cited by 40 publications

References 52 publications

Fluorinated Bifunctional Solid Polymer Electrolyte Synthesized under Visible Light for Stable Lithium Deposition and Dendrite‐Free All‐Solid‐State Batteries

Fluorinated Bifunctional Solid Polymer Electrolyte Synthesized under Visible Light for Stable Lithium Deposition and Dendrite‐Free All‐Solid‐State Batteries

Toward Unraveling the Origin of Lithium Fluoride in the Solid Electrolyte Interphase

Review on nanomaterials for next‐generation batteries with lithium metal anodes

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