scholarly journals Ultrathin conformal polycyclosiloxane films to improve silicon cycling stability

2019 ◽  
Vol 5 (7) ◽  
pp. eaaw4856 ◽  
Author(s):  
B. H. Shen ◽  
S. Wang ◽  
W. E. Tenhaeff
Keyword(s):  
Photoelectron Spectroscopy ◽  
Coulombic Efficiency ◽  
Lithium Ion ◽  
Chemical Vapor ◽  
Silicon Thin Film ◽  
Capacity Retention ◽  
Initiated Chemical Vapor Deposition ◽  
Current Densities ◽  
Si Anodes ◽  
Further Development

Electrochemical reduction of lithium ion battery electrolyte on Si anodes was mitigated by synthesizing nanoscale, conformal polymer films as artificial solid electrolyte interface (SEI) layers. Initiated chemical vapor deposition (iCVD) was used to deposit poly(1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane) (pV4D4) onto silicon thin film electrodes. pV4D4 films (25 nm) on Si electrodes improved initial coulombic efficiency by 12.9% and capacity retention over 100 cycles by 64.9% relative to untreated electrodes. pV4D4 coatings improved rate capabilities, enabling higher lithiation capacity at all current densities. Impedance spectroscopy showed that SEI resistance grew from 50 to 191 ohms in untreated Si and only 34 to 90 ohms in pV4D4-coated Si over 30 cycles. Post-cycling Fourier transform infrared and x-ray photoelectron spectroscopy showed that pV4D4 moderated electrolyte reduction and altered SEI composition, with LiF formation being favored. This work will guide further development of polymeric artificial SEIs to mitigate electrolyte reduction and enhance capacity retention in Si electrodes.

scholarly journals Atomic layer deposited V2O5 coatings: a promising cathode for Li-ion batteries

2019 ◽  
Vol 10 (1) ◽  
pp. 21-28
Author(s):  
Martyn Pemble ◽  
Ian Povey ◽  
Dimitra Vernardou
Keyword(s):  
Vanadium Pentoxide ◽  
Coulombic Efficiency ◽  
Lithium Ion ◽  
Chemical Vapor ◽  
Atomic Layer ◽  
Deposition Process ◽  
Chemical Vapor Deposition Growth ◽  
Layer Deposition ◽  
Specific Discharge ◽  
Cathodic And Anodic Processes

A modified, thermal atomic layer deposition process was employed for the pulsed chemical vapor deposition growth of vanadium pentoxide films using tetrakis (dimethylamino) vanadium and water as a co-reagent.Depositions were carried out at 350oC for 400 pulsed CVD cycles, and samples were subsequently annealed for 1hour at 400°C in air to form materials with enhanced cycling stability during the continuous lithium-ion intercala­tion/deintercalation processes. The diffusion coefficient was estimated to be 2.04x10-10 and 4.10x10-10 cm2 s-1 for the cathodic and anodic processes, respectively. These values are comparable or lower than those reported in the literature, indicating the capability of Li+ of getting access into the vanadium pentoxide framework at a fast rate. Overall, it presents a specific discharge capacity of 280 mAh g-1, capacity retention of 75 % after 10000 scans, a coulombic efficiency of 100 % for the first scan, dropping to 85 % for the 10000th scan, and specific energy of 523 Wh g-1.

scholarly journals A conductive self healing polymeric binder using hydrogen bonding for Si anodes in lithium ion batteries

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jaebin Nam ◽  
Eunsoo Kim ◽  
Rajeev K.K. ◽  
Yeonho Kim ◽  
Tae-Hyun Kim
Keyword(s):  
Hydrogen Bonding ◽  
Acrylic Acid ◽  
Lithium Ion Batteries ◽  
Coulombic Efficiency ◽  
Lithium Ion ◽  
Polymer Binder ◽  
Self Healing ◽  
Si Anodes ◽  
Ion Conducting ◽  
Poly Acrylic Acid

Abstract A ureido-pyrimidinone (UPy)-functionalized poly(acrylic acid) grafted with poly(ethylene glycol)(PEG), designated PAU-g-PEG, was developed as a high performance polymer binder for Si anodes in lithium-ion batteries. By introducing both a ureido-pyrimidinone (UPy) unit, which is capable of self-healing through dynamic hydrogen bonding within molecules as well as with Si, and an ion-conducting PEG onto the side chain of the poly(acrylic acid), this water-based self-healable and conductive polymer binder can effectively accommodate the volume changes of Si, while maintaining electronic integrity, in an electrode during repeated charge/discharge cycles. The Si@PAU-g-PEG electrode retained a high capacity of 1,450.2 mAh g−1 and a Coulombic efficiency of 99.4% even after 350 cycles under a C-rate of 0.5 C. Under a high C-rate of 3 C, an outstanding capacity of 2,500 mAh g−1 was also achieved, thus demonstrating its potential for improving the electrochemical performance of Si anodes.

Si nanoflake-assembled blocks towards high initial coulombic efficiency anodes for lithium-ion batteries

2018 ◽  
Vol 54 (86) ◽  
pp. 12214-12217 ◽  
Author(s):  
Xiangyang Zhou ◽  
Yongpeng Ren ◽  
Juan Yang ◽  
Jing Ding ◽  
Jiaming Zhang ◽  
...  
Keyword(s):  
Lithium Ion Batteries ◽  
Coulombic Efficiency ◽  
Lithium Ion ◽  
Si Anodes ◽  
Initial Coulombic Efficiency

The initial coulombic efficiency of Si anodes is effectively improved via a Cu assisted Mg reduction.

scholarly journals Structural Effects of Anomalous Current Densities on Manganese Hexacyanoferrate for Li-Ion Batteries

2020 ◽  
Vol 10 (21) ◽  
pp. 7573
Author(s):  
Angelo Mullaliu ◽  
Stéphanie Belin ◽  
Lorenzo Stievano ◽  
Marco Giorgetti ◽  
Stefano Passerini
Keyword(s):  
Coulombic Efficiency ◽  
Lithium Ion ◽  
Electrochemical Process ◽  
Remaining Useful Life ◽  
Multivariate Curve Resolution ◽  
Battery Management System ◽  
Battery Management ◽  
Structural Effects ◽  
Current Densities ◽  
Li Ion

A battery management system (BMS) plays a pivotal role in providing optimal performance of lithium-ion batteries (LIBs). However, the eventual malfunction of the BMS may lead to safety hazards or reduce the remaining useful life of LIBs. Manganese hexacyanoferrate (MnHCF) was employed as the positive electrode material in a Li-ion half-cell and subjected to five cycles at high current densities (10 A gMnHCF−1) and to discharge at 0.1 A gMnHCF−1, instead of classical charge/discharge cycling with initial positive polarization at 0.01 A gMnHCF−1, to simulate a current sensor malfunctioning and to evaluate the electrochemical and structural effects on MnHCF. The operando set of spectra at the Mn and Fe K-edges was further analyzed through multivariate curve resolution analysis with an alternating least squares algorithm (MCR–ALS) and extended X-ray absorption fine structure (EXAFS) spectroscopy to investigate the structural modifications arising during cycling after the applied electrochemical protocol. The coulombic efficiency in the first cycle was dramatically affected; however, the local structural environment around each photo absorber recovered during charging. The identification of an additional spectral contribution in the electrochemical process was achieved through MCR-ALS analysis, and the Mn-local asymmetry was thoroughly explored via EXAFS analysis.

scholarly journals Li2O-Based Cathode Additives Enabling Prelithiation of Si Anodes

2021 ◽  
Vol 11 (24) ◽  
pp. 12027
Author(s):  
Yeyoung Ha ◽  
Maxwell C. Schulze ◽  
Sarah Frisco ◽  
Stephen E. Trask ◽  
Glenn Teeter ◽  
...  
Keyword(s):  
Coulombic Efficiency ◽  
High Surface ◽  
Solid Electrolyte Interphase ◽  
Active Material ◽  
High Surface Area ◽  
Lithium Ion ◽  
Particle Morphology ◽  
Lithium Oxide ◽  
Si Anodes ◽  
The Impact

Low first-cycle Coulombic efficiency is especially poor for silicon (Si)-based anodes due to the high surface area of the Si-active material and extensive electrolyte decomposition during the initial cycles forming the solid electrolyte interphase (SEI). Therefore, developing successful prelithiation methods will greatly benefit the development of lithium-ion batteries (LiBs) utilizing Si anodes. In pursuit of this goal, in this study, lithium oxide (Li2O) was added to a LiNi0.6Mn0.2Co0.2O2 (NMC622) cathode using a scalable ball-milling approach to compensate for the initial Li loss at the anode. Different milling conditions were tested to evaluate the impact of particle morphology on the additive performance. In addition, Co3O4, a well-known oxygen evolution reaction catalyst, was introduced to facilitate the activation of Li2O. The Li2O + Co3O4 additives successfully delivered an additional capacity of 1116 mAh/gLi2O when charged up to 4.3 V in half cells and 1035 mAh/gLi2O when charged up to 4.1 V in full cells using Si anodes.

scholarly journals Synthesis of High Surface Area α-KyMnO2 Nanoneedles Using Extract of Broccoli as Bioactive Reducing Agent and Application in Lithium Battery

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1269 ◽  
Author(s):  
Ahmed Hashem ◽  
Hanaa Abuzeid ◽  
Martin Winter ◽  
Jie Li ◽  
Christian Julien
Keyword(s):  
Surface Area ◽  
Coulombic Efficiency ◽  
High Surface ◽  
High Surface Area ◽  
Rate Capability ◽  
Lithium Ion ◽  
Reducing Agent ◽  
Capacity Retention ◽  
Transmission Electron ◽  
Initial Capacity

With the aim to reduce the entire cost of lithium-ion batteries and to diminish the environmental impact, the extract of broccoli is used as a strong benign reducing agent for potassium permanganate to synthesize α-KyMnO2 cathode material with pure nanostructured phase. Material purity is confirmed by X-ray powder diffraction and thermogravimetric analyses. Images of transmission electron microscopy show samples with a spider-net shape consisting of very fine interconnected nanoneedles. The nanostructure is characterized by crystallite of 4.4 nm in diameter and large surface area of 160.7 m2 g−1. The material delivers an initial capacity of 211 mAh g−1 with high Coulombic efficiency of 99% and 82% capacity retention after 100 cycles. Thus, α-KyMnO2 synthesized via a green process exhibits very promising electrochemical performance in terms of initial capacity, cycling stability and rate capability.

Lithium-ion storage properties of a micro/nanosheet-like NaV6O15 anode in aqueous solution

2017 ◽  
Vol 46 (12) ◽  
pp. 3857-3863 ◽  
Author(s):  
Mingshu Zhao ◽  
Weigang Zhang ◽  
Xiaoping Song
Keyword(s):  
Aqueous Solution ◽  
Lithium Ion Battery ◽  
Lithium Ion ◽  
Capacity Retention ◽  
Ion Storage ◽  
Current Densities ◽  
Storage Properties

Sheet-like NaV6O15 materials in an aqueous rechargeable lithium-ion battery show increased capacity retention at higher current densities.

scholarly journals Polyethylene glycol and poly(vinyl alcohol) hydrogels treated with photo-initiated chemical vapor deposition

2016 ◽  
Vol 94 (9) ◽  
pp. 744-750 ◽  
Author(s):  
Taraneh Javanbakht ◽  
Ariane Bérard ◽  
Jason R. Tavares
Keyword(s):  
Chemical Vapor Deposition ◽  
Polyethylene Glycol ◽  
Vapor Deposition ◽  
Photoelectron Spectroscopy ◽  
Vinyl Alcohol ◽  
Chemical Vapor ◽  
Molecular Structures ◽  
Poly Vinyl Alcohol ◽  
Chemical Structures ◽  
Initiated Chemical Vapor Deposition

This study was designed to determine if surface modification via photo-initiated chemical vapor deposition (PICVD) affects the physicochemical properties of polyethylene glycol (PEG) and poly(vinyl alcohol) (PVA) differently, given their different chemical structures and properties. Contact angle measurements showed that both polymers increase in surface hydrophobicity after PICVD treatment. Further, the improved hydrophobicity facilitated dispersion into nonpolar solvents. Chemical changes were concentrated near the surface, evidenced by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements, indicating namely that partial oxidation occurs during treatment. These findings were discussed in the context of the difference of the molecular structures of PEG and PVA, which, in turn, control their surface functionalization and hydrophobicity.

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