The Effect of Silicon Grade and Electrode Architecture on the Performance of Advanced Anodes for Next Generation Lithium-Ion Cells

To increase the specific capacity of anodes for lithium-ion cells, advanced active materials, such as silicon, can be utilized. Silicon has an order of magnitude higher specific capacity compared to the state-of-the-art anode material graphite; therefore, it is a promising candidate to achieve this target. In this study, different types of silicon nanopowders were introduced as active material for the manufacturing of composite silicon/graphite electrodes. The materials were selected from different suppliers providing different grades of purity and different grain sizes. The slurry preparation, including binder, additives, and active material, was established using a ball milling device and coating was performed via tape casting on a thin copper current collector foil. Composite electrodes with an areal capacity of approximately 1.70 mAh/cm² were deposited. Reference electrodes without silicon were prepared in the same manner, and they showed slightly lower areal capacities. High repetition rate, ultrafast laser ablation was applied to these high-power electrodes in order to introduce line structures with a periodicity of 200 µm. The electrochemical performance of the anodes was evaluated as rate capability and operational lifetime measurements including pouch cells with NMC 622 as counter electrodes. For the silicon/graphite composite electrodes with the best performance, up to 200 full cycles at a C-rate of 1C were achieved until end of life was reached at 80% relative capacity. Additionally, electrochemical impedance spectroscopies were conducted as a function of state of health to correlate the used silicon grade with solid electrolyte interface (SEI) formation and charge transfer resistance values.

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Electrochemical Properties of Carbon-Coated NbO2 as a Negative Electrode for Lithium-Ion Batteries

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.724.87 ◽

2016 ◽

Vol 724 ◽

pp. 87-91 ◽

Cited By ~ 3

Author(s):

Chang Su Kim ◽

Yong Hoon Cho ◽

Kyoung Soo Park ◽

Soon Ki Jeong ◽

Yang Soo Kim

Keyword(s):

Electrochemical Properties ◽

Lithium Ion Batteries ◽

Ball Milling ◽

Carbon Coating ◽

Electrochemical Impedance ◽

Active Material ◽

Negative Electrode ◽

Lithium Ion ◽

Transfer Resistance ◽

Carbon Coated

We investigated the electrochemical properties of carbon-coated niobium dioxide (NbO2) as a negative electrode material for lithium-ion batteries. Carbon-coated NbO2 powders were synthesized by ball-milling using carbon nanotubes as the carbon source. The carbon-coated NbO2 samples were of smaller particle size compared to the pristine NbO2 samples. The carbon layers were coated non-uniformly on the NbO2 surface. The X-ray diffraction patterns confirmed that the inter-layer distances increased after carbon coating by ball-milling. This lead to decreased charge-transfer resistance, confirmed by electrochemical impedance spectroscopy, allowing electrons and lithium-ions to quickly transfer between the active material and electrolyte. Electrochemical performance, including capacity and initial coulombic efficiency, was therefore improved by carbon coating by ball-milling.

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Improved Electrochemical Performance of Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2 Cathode Material Synthesized by the Polyvinyl Alcohol Auxiliary Sol-Gel Process for Lithium-Ion Batteries

Advances in Condensed Matter Physics ◽

10.1155/2018/1217639 ◽

2018 ◽

Vol 2018 ◽

pp. 1-7

Author(s):

He Wang ◽

Mingning Chang ◽

Yonglei Zheng ◽

Ningning Li ◽

Siheng Chen ◽

...

Keyword(s):

Polyvinyl Alcohol ◽

Cathode Material ◽

Discharge Capacity ◽

Electrochemical Impedance ◽

Coulombic Efficiency ◽

Sol Gel ◽

Rate Capability ◽

Lithium Ion ◽

Transfer Resistance ◽

Sol Gel Process

A lithium-rich manganese-based cathode material, Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2, was prepared using a polyvinyl alcohol (PVA)-auxiliary sol-gel process using MnO2 as a template. The effect of the PVA content (0.0–15.0 wt%) on the electrochemical properties and morphology of Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2 was investigated. Analysis of Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2 X-ray diffraction patterns by RIETAN-FP program confirmed the layered α-NaFeO2 structure. The discharge capacity and coulombic efficiency of Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2 in the first cycle were improved with increasing PVA content. In particular, the best material reached a first discharge capacity of 206.0 mAhg−1 and best rate capability (74.8 mAhg−1 at 5 C). Meanwhile, the highest capacity retention was 87.7% for 50 cycles. Finally, electrochemical impedance spectroscopy shows that as the PVA content increases, the charge-transfer resistance decreases.

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Electrochemical Impedance Spectroscopy on the Performance Degradation of LiFePO4/Graphite Lithium-Ion Battery Due to Charge-Discharge Cycling under Different C-Rates

Energies ◽

10.3390/en12234507 ◽

2019 ◽

Vol 12 (23) ◽

pp. 4507 ◽

Cited By ~ 11

Author(s):

Yusuke Abe ◽

Natsuki Hori ◽

Seiji Kumagai

Keyword(s):

Charge Transfer ◽

Electrochemical Impedance Spectroscopy ◽

Impedance Spectroscopy ◽

Electrochemical Impedance ◽

Specific Capacity ◽

Lithium Ion ◽

Performance Degradation ◽

Charge Transfer Resistance ◽

Transfer Resistance ◽

Charge Discharge

Lithium-ion batteries (LIBs) using a LiFePO4 cathode and graphite anode were assembled in coin cell form and subjected to 1000 charge-discharge cycles at 1, 2, and 5 C at 25 °C. The performance degradation of the LIB cells under different C-rates was analyzed by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy. The most severe degradation occurred at 2 C while degradation was mitigated at the highest C-rate of 5 C. EIS data of the equivalent circuit model provided information on the changes in the internal resistance. The charge-transfer resistance within all the cells increased after the cycle test, with the cell cycled at 2 C presenting the greatest increment in the charge-transfer resistance. Agglomerates were observed on the graphite anodes of the cells cycled at 2 and 5 C; these were more abundantly produced in the former cell. The lower degradation of the cell cycled at 5 C was attributed to the lowered capacity utilization of the anode. The larger cell voltage drop caused by the increased C-rate reduced the electrode potential variation allocated to the net electrochemical reactions, contributing to the charge-discharge specific capacity of the cells.

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Boosting the Rate and Cycling Performance of β-LixV2O5 Nanorods for Li Ion Battery by Electrode Surface Decoration

10.26434/chemrxiv.9791540.v1 ◽

2019 ◽

Author(s):

Panpan Wang ◽

Yue Du ◽

Baoyou Zhang ◽

Yanxin Yao ◽

Yuchen Xiao ◽

...

Keyword(s):

Electrochemical Performance ◽

Current Density ◽

Electrochemical Impedance ◽

Electronic Conductivity ◽

Specific Capacity ◽

Rate Capability ◽

Lithium Ion ◽

Ex Situ ◽

Practical Application ◽

Surface Decoration

The β-phase lithium vanadium oxide bronze (β-LixV2O5) with high theoretic specific capacity up to 440 mAh g-1 is considered as promising cathode materials, however, their practical application is hindered by its poor ionic and electronic conductivity, resulting in unsatisfied cyclic stability and rate capability. Herein, we report the surface decoration of β-LixV2O5 cathode using both reduced oxide graphene and ionic conductor LaPO4, which significantly promotes the electronic transfer and Li+ diffusion rate, respectively. As a result, the rGO/LaPO4/LixV2O5 composite exhibits excellent electrochemical performance in terms of high reversible specific capacity of 275.7 mAh g-1 with high capacity retention of 84.1% after 100 cycles at a current density of 60 mA g-1, and acceptable specific capacity of 170.3 mAh g-1 at high current density of 400 mA g-1. The cycled electrode is also analyzed by electrochemical impedance spectroscopy, ex-situ X-ray diffraction and scanning electron microscope, providing further insights into the improvement of electrochemical performance. Our results provide an effective approach to boost the electrochemical properties of lithium vanadates for practical application in lithium ion batteries.

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Utilizing the Intrinsic Thermal Instability of Swedenborgite Structured YBaCo4O7+δ as an Opportunity for Material Engineering in Lithium-Ion Batteries by Er and Ga Co-Doping Processes

Materials ◽

10.3390/ma14164565 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4565

Author(s):

Sanghyuk Park ◽

Kwangho Park ◽

Ji-Seop Shin ◽

Gyeongbin Ko ◽

Wooseok Kim ◽

...

Keyword(s):

Lithium Ion Batteries ◽

Phase Stability ◽

Electrochemical Impedance ◽

Coulombic Efficiency ◽

Structural Phase ◽

Active Material ◽

Rate Capability ◽

Lithium Ion ◽

Ion Migration ◽

Co Doping

We firstly introduce Er and Ga co-doped swedenborgite-structured YBaCo4O7+δ (YBC) as a cathode-active material in lithium-ion batteries (LIBs), aiming at converting the phase instability of YBC at high temperatures into a strategic way of enhancing the structural stability of layered cathode-active materials. Our recent publication reported that Y0.8Er0.2BaCo3.2Ga0.8O7+δ (YEBCG) showed excellent phase stability compared to YBC in a fuel cell operating condition. By contrast, the feasibility of the LiCoO2 (LCO) phase, which is derived from swedenborgite-structured YBC-based materials, as a LIB cathode-active material is investigated and the effects of co-doping with the Er and Ga ions on the structural and electrochemical properties of Li-intercalated YBC are systemically studied. The intrinsic swedenborgite structure of YBC-based materials with tetrahedrally coordinated Co2+/Co3+ are partially transformed into octahedrally coordinated Co3+, resulting in the formation of an LCO layered structure with a space group of R-3m that can work as a Li-ion migration path. Li-intercalated YEBCG (Li[YEBCG]) shows effective suppression of structural phase transition during cycling, leading to the enhancement of LIB performance in Coulombic efficiency, capacity retention, and rate capability. The galvanostatic intermittent titration technique, cyclic voltammetry and electrochemical impedance spectroscopy are performed to elucidate the enhanced phase stability of Li[YEBCG].

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The Role of Silicon in Silicon-Graphite Composite Electrodes Regarding Specific Capacity, Cycle Stability, and Expansion

Journal of The Electrochemical Society ◽

10.1149/1945-7111/ac4545 ◽

2021 ◽

Author(s):

Erfan Moyassari ◽

Thomas Roth ◽

Simon Kücher ◽

C. C. Chang ◽

Shang-Chieh Hou ◽

...

Keyword(s):

Electrochemical Performance ◽

Silicon Content ◽

Volume Expansion ◽

Active Material ◽

Specific Capacity ◽

Lithium Ion ◽

Clear Correlation ◽

Graphite Composite ◽

Thickness Change ◽

Capacity Loss

Abstract One promising way of compensating for the repeated volume expansion and contraction of silicon as an anode active material in lithium ion batteries (LIBs) is to embed silicon within a graphite matrix. Silicon-graphite (SiG) composites combine the advantageous properties of graphite, i.e., large electrical conductivity and high structural stability, with the advantageous properties of silicon, i.e., high theoretical capacity. Graphite has a much lower volume expansion upon lithiation (≈ 10%) than pure silicon (≈ 300%) and provides a mechanically stable matrix. Herein, we present an investigation into the electrochemical performance and thickness change behavior of porous SiG anode compositions with silicon contents ranging from 0 wt% to 20 wt%. The electrode composites were studied using two methods: in situ dilatometry for the thickness change investigation and conventional coin cells for the assessment of electrochemical performance. The measurements show that the initial thickness change of SiG electrodes increased significantly with the silicon content, but it leveled off during cycling for all compositions. There appears to be a correlation between silicon content and capacity loss, but no clear correlation between thickness change and capacity loss rate was found.

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Enhanced Electrochemical Performances of LiFePO4/C Cathode Materials by Deposited with Ge Film

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.936.480 ◽

2014 ◽

Vol 936 ◽

pp. 480-485

Author(s):

Yan Dan Huang ◽

Ying Bin Lin ◽

Zhi Gao Huang

Keyword(s):

Impedance Spectroscopy ◽

Electrochemical Impedance ◽

Active Material ◽

Rate Capability ◽

Film Surface ◽

Charge Transfer Resistance ◽

Electrochemical Performances ◽

Cyclic Voltammograms ◽

Transfer Resistance ◽

Surface Modified

LiFePO4/C-Ge electrodes were prepared with vacuum thermal evaporation deposition by depositing Ge films on as-prepared LiFePO4/C electrodes. The effect of Ge film on the electrochemical performances of LiFePO4/C cells was investigated systematically by charge/discharge testing, cyclic voltammograms and AC impedance spectroscopy, respectively. It was found that Ge-film-surface modified LiFePO4/C showed excellent electrochemical performances compared to that of the pristine one in terms of cyclability and rate capability. At 60°C, LiFePO4/C-Ge film exhibited outstanding cyclability with less than 5% capacity fade after 50 cycles while the pristine one suffers 15%. Analysis from the electrochemical measurements showed that the presence of Ge film on the LiFePO4/C electrode would protect active material from HF generated by the decomposition of LiPF6 in the electrolyte and stabilize the surface structure of active material during the charge and discharge cycle. Electrochemical impedance spectroscopy (EIS) results indicated that Ge film mainly reduced the charge transfer resistance Rct of LiFePO4/C electrode, resulting from the suppression of the solid electrolyte interfacial (SEI) film.

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Facile Synthesis of Polypyrrole Nanofibers/Co-MOF Composite and Its Lithium Storage Properties

Science of Advanced Materials ◽

10.1166/sam.2020.3630 ◽

2020 ◽

Vol 12 (4) ◽

pp. 486-491

Author(s):

Jinlei Wang ◽

Na Cao ◽

Huiling Du ◽

Xian Du ◽

Hai Lu ◽

...

Keyword(s):

Electrode Materials ◽

Rate Capability ◽

Lithium Ion ◽

Reversible Capacity ◽

Cycling Performance ◽

Charge Transfer Resistance ◽

Growth Strategy ◽

Composite Electrodes ◽

Lithium Storage ◽

Transfer Resistance

Metal-organic frameworks (MOFs) have recently emerged as promising electrode materials for lithium-ion batteries (LIBs). However, poor electrical conductivity in most MOFs limits their electrochemical performance. In this work, the integration of flaky cobalt 1,4-benzenedicarboxylate (Co-BDC) MOF with conductive polypyrrole (PPy) nanofibers via in-situ growth strategy was explored for developing novel anode materials for LIBs. Electrochemical studies showed that PPy/Co-BDC composites exhibited enhanced cycling performance (a reversible capacity of ca. 364 mA h g–1 at a current density of 50 mA g–1 after 100 cycles) and rate capability, com- pared with the pristine Co-BDC. The well dispersion of Co-BDC on polypyrrole nanofibers and the decrease in charge-transfer resistance of the composite electrodes accounted for the improvement of electrochemical properties.

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Preparation and Electrochemical Performance of Mg2 + Doped Li4Ti5O12 Anode Materials for Lithium-Ion Batteries

Materials Science Forum ◽

10.4028/www.scientific.net/msf.960.238 ◽

2019 ◽

Vol 960 ◽

pp. 238-243

Author(s):

Ming Wang ◽

Xue Ming Zhang ◽

Ying Bo Wang ◽

Li Li Cheng ◽

Xue Lei Wang ◽

...

Keyword(s):

Electrochemical Performance ◽

Electrochemical Impedance ◽

Solid Phase ◽

Retention Rate ◽

Specific Capacity ◽

Lithium Ion ◽

Charge Transfer Resistance ◽

Solid Phase Reaction ◽

Phase Reaction ◽

Transfer Resistance

Spinel Li4Ti5O12 (LTO) doped with Mg2+ was synthesized by solid-phase reaction method. The Mg2+ doping quantity was 3%, 6%, 9%, and 12%, respectively. The structure and electrochemical performance of the prepared LTO composites were investigated by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Electrochemical Impedance Spectroscopy (EIS), and galvanostatic charge-discharge tests. It was found that the doped Mg ion did not change the structure of Li4Ti5O12, and it was evenly distributed around Li4Ti5O12. When Mg2+ doping quantity increased from 3% to 12%, the internal resistance and charge transfer resistance of the composite both decreased. The first discharge specific capacity of 6%-Mg2+ doped LTO composite was 168 mAh/g, which was close to the theoretical capacity of pure lithium titanate (175 mAh/g), and the capacity retention rate was 98% after 100 cycles.

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Synthesis and electrochemical properties of SrWO4/graphene composite as anode material for lithium-ion batteries

Functional Materials Letters ◽

10.1142/s1793604714500106 ◽

2014 ◽

Vol 07 (02) ◽

pp. 1450010 ◽

Cited By ~ 8

Author(s):

Linsen Zhang ◽

Qingling Bai ◽

Linzhen Wang ◽

Aiqin Zhang ◽

Yong Zhang ◽

...

Keyword(s):

Electrochemical Impedance ◽

Sol Gel ◽

Specific Capacity ◽

Rate Capability ◽

Lithium Ion ◽

Cycle Performance ◽

Electrochemical Performances ◽

Graphene Composite ◽

Discharge Method ◽

Charge Discharge

SrWO 4/graphene composite was synthesized via a sol–gel method. The morphology and structure of the products were analyzed by SEM, TEM and XRD. The electrochemical performances of SrWO 4/graphene composite were investigated by galvanostatic charge/discharge method, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results showed that the first cycle of the reversible specific capacity of SrWO 4/graphene composite can reach to 575.9 mAh g-1 at 50 mA g-1. The charge/discharge cycling study indicates that the SrWO 4/graphene composite was provided with excellent cycle performance and outstanding rate capability.

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