The Effect of Solvent on the Capacity Retention in a Germanium Anode for Lithium Ion Batteries

<div>The formation of c-Li3.75Si is known to be detrimental to silicon anodes in lithium-ion batteries. To suppress the formation of this crystalline phase and improve the electrochemical performance of Sibased anodes, three approaches were amalgamated: addition of a nickel adhesion sublayer, alloying of the silicon with titanium, and the addition of either carbon or TiO2 as a capping layer. The silicon-based films were analyzed by a suite of methods, including scanning electron microscopy (SEM) and a variety of electrochemical methods, as well as X-ray photoelectron spectroscopy (XPS) to provide insights into the composition of the resulting solid electrolyte interphase (SEI). A nickel adhesion layer decreased the extent of delamination of the silicon from the underlying copper substrate, compared to Si deposited directly on Cu, which resulted in less capacity loss. Alloying of silicon with titanium (85% silicon, 15% titanium) further increased the stability. Finally, capping these multilayer electrodes with either a thin 10 nm layer of carbon or TiO2 resulted in the best electrode behavior, and lowest cumulative relative irreversible capacity. TiO2 is slightly more effective in enhancing the capacity retention, most likely due to differences in the resulting solid electrolyte interphase (SEI). The combination of an adhesion layer, alloying, and surface coatings shows a cumulative suppression of the formation of c-Li3.75Si and SEI, resulting in the greatest improvement of capacity retention when all three are incorporated together. However, these strategies appear to only delay the onset of the c-Li3.75Si phase; eventually, the c-Li3.75Si phase will form, and at that point, the rate of capacity degradation of all the electrodes becomes similar.</div>

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Adhesion and Surface Layers on Silicon Anodes Suppress Formation of c-Li3.75Si and Solid Electrolyte Interphase

10.26434/chemrxiv.10029068 ◽

2019 ◽

Author(s):

Hezhen Xie ◽

Sayed Youssef Sayed ◽

W. Peter Kalisvaart ◽

Simon Jakob Schaper ◽

Peter Müller-Buschbaum ◽

...

Keyword(s):

Solid Electrolyte ◽

Photoelectron Spectroscopy ◽

Solid Electrolyte Interphase ◽

Copper Substrate ◽

Lithium Ion ◽

Adhesion Layer ◽

Capacity Retention ◽

Silicon Anodes ◽

Capacity Degradation ◽

The Stability

<div>The formation of c-Li3.75Si is known to be detrimental to silicon anodes in lithium-ion batteries. To suppress the formation of this crystalline phase and improve the electrochemical performance of Sibased anodes, three approaches were amalgamated: addition of a nickel adhesion sublayer, alloying of the silicon with titanium, and the addition of either carbon or TiO2 as a capping layer. The silicon-based films were analyzed by a suite of methods, including scanning electron microscopy (SEM) and a variety of electrochemical methods, as well as X-ray photoelectron spectroscopy (XPS) to provide insights into the composition of the resulting solid electrolyte interphase (SEI). A nickel adhesion layer decreased the extent of delamination of the silicon from the underlying copper substrate, compared to Si deposited directly on Cu, which resulted in less capacity loss. Alloying of silicon with titanium (85% silicon, 15% titanium) further increased the stability. Finally, capping these multilayer electrodes with either a thin 10 nm layer of carbon or TiO2 resulted in the best electrode behavior, and lowest cumulative relative irreversible capacity. TiO2 is slightly more effective in enhancing the capacity retention, most likely due to differences in the resulting solid electrolyte interphase (SEI). The combination of an adhesion layer, alloying, and surface coatings shows a cumulative suppression of the formation of c-Li3.75Si and SEI, resulting in the greatest improvement of capacity retention when all three are incorporated together. However, these strategies appear to only delay the onset of the c-Li3.75Si phase; eventually, the c-Li3.75Si phase will form, and at that point, the rate of capacity degradation of all the electrodes becomes similar.</div>

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Characterization of SEI Layer Formed on Tin Film Anode

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.512-515.1869 ◽

2012 ◽

Vol 512-515 ◽

pp. 1869-1872 ◽

Cited By ~ 3

Author(s):

Ling Zhi Zhao ◽

Xin Fang Lai ◽

Qiao Li Niu ◽

Chang Ming Li

Keyword(s):

Lithium Ion Battery ◽

Photoelectron Spectroscopy ◽

Solid Electrolyte Interphase ◽

Lithium Ion ◽

Carbon Anode ◽

Discharge Process ◽

Tin Film ◽

Sei Layer ◽

Cu Foil ◽

Foil Substrate

Tin thin film on Cu foil substrate as the anode of lithium ion battery was prepared by direct current (DC) magnetron sputtering. The surface morphology and the solid electrolyte interphase (SEI) layer were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS). It is found that the SEI layer should be formed on the surface of the tin electrode after initial discharge processes, just like the carbon anode of lithium ion battery. The SEI layer undergoes continuous reformation during the initial cycles. The tin in the electrode can be covered completely by SEI layer after 3rd discharge process. The carbon in SEI layer is mainly in the form of -CO32- , which makes up about 54.5 at%.

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Butyronitrile-Based Electrolytes for Fast Charging of Lithium-Ion Batteries

Energies ◽

10.3390/en12152869 ◽

2019 ◽

Vol 12 (15) ◽

pp. 2869 ◽

Cited By ~ 4

Author(s):

Peter Hilbig ◽

Lukas Ibing ◽

Martin Winter ◽

Isidora Cekic-Laskovic

Keyword(s):

Ionic Conductivity ◽

Ethylene Carbonate ◽

Solid Electrolyte Interphase ◽

Depth Profiling ◽

Lithium Ion ◽

Cycling Performance ◽

Fast Charging ◽

Fluoroethylene Carbonate ◽

Solvent Additive

After determining the optimum composition of the butyronitrile: ethylene carbonate: fluoroethylene carbonate (BN:EC:FEC) solvent/co-solvent/additive mixture, the resulting electrolyte formulation (1M LiPF6 in BN:EC (9:1) + 3% FEC) was evaluated in terms of ionic conductivity and the electrochemical stability window, as well as galvanostatic cycling performance in NMC/graphite cells. This cell chemistry results in remarkable fast charging, required, for instance, for automotive applications. In addition, a good long-term cycling behavior lasts for 1000 charge/discharge cycles and improved ionic conductivity compared to the benchmark counterpart was achieved. XPS sputter depth profiling analysis proved the beneficial behavior of the tuned BN-based electrolyte on the graphite surface, by confirming the formation of an effective solid electrolyte interphase (SEI).

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Effects of Structural Substituents on the Electrochemical Decomposition of Carbonyl Derivatives and Formation of the Solid–Electrolyte Interphase in Lithium-Ion Batteries

Energies ◽

10.3390/en14217352 ◽

2021 ◽

Vol 14 (21) ◽

pp. 7352

Author(s):

S. Hamidreza Beheshti ◽

Mehran Javanbakht ◽

Hamid Omidvar ◽

Hamidreza Behi ◽

Xinhua Zhu ◽

...

Keyword(s):

Solid Electrolyte ◽

Lithium Ion Batteries ◽

Elevated Temperatures ◽

Solid Electrolyte Interphase ◽

Lithium Ion ◽

Comparative Approach ◽

Capacity Retention ◽

Decomposition Products ◽

Carbonyl Derivatives

The solid–electrolyte interphase (SEI), the passivation layer formed on anode particles during the initial cycles, affects the performance of lithium-ion batteries (LIBs) in terms of capacity, power output, and cycle life. SEI features are dependent on the electrolyte content, as this complex layer originates from electrolyte decomposition products. Despite a variety of studies devoted to understanding SEI formation, the complexity of this process has caused uncertainty in its chemistry. In order to clarify the role of the substituted functional groups of the SEI-forming compounds in their efficiency and the features of the resulting interphase, the performance of six different carbonyl-based molecules has been investigated by computational modeling and electrochemical experiments with a comparative approach. The performance of the electrolytes and stability of the generated SEI are evaluated in both half-cell and full-cell configurations. Added to the room-temperature studies, the cyclability of the NMC/graphite cells is assessed at elevated temperatures as an intensified aging condition. The results show that structural adjustments within the SEI-forming molecule can ameliorate the cyclability of the electrolyte, leading to a higher capacity retention of the LIB cell, where cinnamoyl chloride is introduced as a novel and more sustainable SEI forming agent with the potential of improving the LIB capacity retention.

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Effect of Fluoroethylene Carbonate Additive on the Initial Formation of Solid Electrolyte Interphase on Oxygen Functionalized Graphitic Anode in Lithium Ion Batteries

10.26434/chemrxiv.13139585 ◽

2020 ◽

Author(s):

Nadia Intan ◽

Jim Pfaendtner

Keyword(s):

Solid Electrolyte ◽

Lithium Ion Batteries ◽

Density Functional ◽

Reaction Pathway ◽

Ethylene Carbonate ◽

Solid Electrolyte Interphase ◽

Lithium Ion ◽

Cell Decomposition ◽

Ab Initio Molecular Dynamics ◽

Fluoroethylene Carbonate

The formation of a solid electrolyte interphase (SEI) at the electrode/electrolyte interface substantially affects the stability and lifetime of lithium-ion batteries (LIBs). One of the methods to improve the lifetime of LIBs is by the inclusion of additive molecules to stabilize the SEI. To understand the effect of additive molecules on the initial stage of SEI formation, we compare the decomposition and oligomerization reactions of a fluoroethylene carbonate (FEC) additive on a range of oxygen functionalized graphitic anode to those of an ethylene carbonate (EC) organic electrolyte. A series of density functional theory (DFT) calculations augmented by ab-initio molecular dynamics (AIMD) simulations reveal that EC decomposition on an oxygen functionalized graphitic (1120) edge facet through an SN2 mechanism is spontaneous, even in an uncharged cell. Decomposition of EC through an SN2 reaction pathway results in alkoxide species regeneration which is responsible for continual oligomerization along the graphitic surface. In contrast, FEC prefers to decompose through an SN1 pathway, which does not promote alkoxide regeneration. The ability of FEC as an additive to suppress alkoxide regeneration results in a smaller and thinner SEI layer that is more flexible towards lithium intercalation during the charging/discharging process. In addition, the presence of different oxygen functional groups at the surface of graphite dictates the oligomerization products and LiF formation in the SEI.

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Experimental and Modeling Analysis of Holey Graphene Electrodes for High-Power-Density Li-Ion Batteries

Crystals ◽

10.3390/cryst10111063 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1063

Author(s):

Yu-Ren Huang ◽

Cheng-Lung Chen ◽

Nen-Wen Pu ◽

Chia-Hung Wu ◽

Yih-Ming Liu ◽

...

Keyword(s):

Ion Transport ◽

Ethylene Carbonate ◽

Solid Electrolyte Interphase ◽

Specific Capacity ◽

Rate Capability ◽

Lithium Ion ◽

Md Simulations ◽

Sei Layer ◽

Uniform Dispersion ◽

Li Ion

The performances of lithium-ion batteries (LIBs) using holey graphene (HGNS) as the anode material are compared with those using non-holey graphene (GNS). The effects of graphene holes on ion transport are analyzed with a combined experiment/modeling approach involving molecular dynamics (MD) simulations. The large aspect ratio of GNS leads to long transport paths for Li ions, and hence a poor rate capability. We demonstrate by both experiments and simulations that the holey structure can effectively improve the rate capability of LIBs by providing shortcuts for Li ion diffusion through the holes in fast charge/discharge processes. The HGNS anode exhibits a high specific capacity of 745 mAh/g at 0.1 A/g (after 80 cycles) and 141 mAh/g at a large current density of 10 A/g, which are higher than the capacity values of the GNS counterpart by 75% and 130%, respectively. MD simulations also reveal the difference in lithium ion transport between GNS and HGNS anodes. The calculations indicate that the HGNS system has a higher diffusion coefficient for lithium ions than the GNS system. In addition, it shows that the holey structure can improve the uniformity and quality of the solid electrolyte interphase (SEI) layer, which is important for Li ion conduction across this layer to access the electrode surface. Moreover, quantum chemistry (QC) computations show that ethylene carbonate (EC), a cyclic carbonate electrolyte with five-membered-ring molecules, has the lowest electron binding energy of 1.32 eV and is the most favorable for lithium-ion transport through the SEI layer. A holey structure facilitates uniform dispersion of EC on graphene sheets and thus enhances the Li ion transport kinetics.

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Role of binders in solid electrolyte interphase formation in lithium ion batteries studied with hard X-ray photoelectron spectroscopy

Journal of Materials Research ◽

10.1557/jmr.2018.363 ◽

2018 ◽

Vol 34 (1) ◽

pp. 97-106 ◽

Cited By ~ 1

Author(s):

Benjamin T. Young ◽

Cao Cuong Nguyen ◽

Anton Lobach ◽

David R. Heskett ◽

Joseph C. Woicik ◽

...

Keyword(s):

Solid Electrolyte ◽

Lithium Ion Batteries ◽

Photoelectron Spectroscopy ◽

Solid Electrolyte Interphase ◽

Lithium Ion ◽

X Ray ◽

Image Position

Abstract

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Effect of Fluoroethylene Carbonate Additive on the Initial Formation of Solid Electrolyte Interphase on Oxygen Functionalized Graphitic Anode in Lithium Ion Batteries

10.26434/chemrxiv.13139585.v1 ◽

2020 ◽

Author(s):

Nadia Intan ◽

Jim Pfaendtner

Keyword(s):

Solid Electrolyte ◽

Lithium Ion Batteries ◽

Density Functional ◽

Reaction Pathway ◽

Ethylene Carbonate ◽

Solid Electrolyte Interphase ◽

Lithium Ion ◽

Cell Decomposition ◽

Ab Initio Molecular Dynamics ◽

Fluoroethylene Carbonate

The formation of a solid electrolyte interphase (SEI) at the electrode/electrolyte interface substantially affects the stability and lifetime of lithium-ion batteries (LIBs). One of the methods to improve the lifetime of LIBs is by the inclusion of additive molecules to stabilize the SEI. To understand the effect of additive molecules on the initial stage of SEI formation, we compare the decomposition and oligomerization reactions of a fluoroethylene carbonate (FEC) additive on a range of oxygen functionalized graphitic anode to those of an ethylene carbonate (EC) organic electrolyte. A series of density functional theory (DFT) calculations augmented by ab-initio molecular dynamics (AIMD) simulations reveal that EC decomposition on an oxygen functionalized graphitic (1120) edge facet through an SN2 mechanism is spontaneous, even in an uncharged cell. Decomposition of EC through an SN2 reaction pathway results in alkoxide species regeneration which is responsible for continual oligomerization along the graphitic surface. In contrast, FEC prefers to decompose through an SN1 pathway, which does not promote alkoxide regeneration. The ability of FEC as an additive to suppress alkoxide regeneration results in a smaller and thinner SEI layer that is more flexible towards lithium intercalation during the charging/discharging process. In addition, the presence of different oxygen functional groups at the surface of graphite dictates the oligomerization products and LiF formation in the SEI.

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