Composite Cathode For Lithium Ion Batteries Research Articles

High-performance 0.75Li3V2(PO4)3·0.25Li3PO4/C composite cathode for lithium-ion batteries

High-performance 0.75Li3V2(PO4)3·0.25Li3PO4/C composite cathode for lithium-ion batteries

Dual-type confinement strategy: Improving the stability of organic composite cathodes for Lithium-ion batteries with longer lifespan

Inclusive reports on organic cathodes are the key evidence of their superior performance for Lithium-ion batteries. However, it is still promising to simultaneously achieve a higher practical specific capacity and longer cycling life, owing to the crucial concern of the dissolution of active molecules in organic electrolytes. The introduction of porous carbon confinement and coating which can impart discharge capacity and cycling stability, is highly beneficial. Herein, we designed and prepared a novel composite cathode (designated as HKUST-1-C@DHAQ@TiO2) with small molecules (DHAQ) in porous carbon skeleton (HKUST-1-C) as core and TiO2 as shell. The unique dual-type confinement strategy offers short Li+/e- diffusion directions for redox reactions and superior structural stability during cycling without dissolution or decomposition of the components, resulting in excellent electrochemical performance. The HKUST-1-C@DHAQ@TiO2 cathode delivers significant specific capacity (209 mAh g−1, 0.1 A g−1), markable Coulombic efficiency (nearly 100 %), notable cycling stability (86 % retention for provided 200 cycles) and excellent rate capacity (138 mAh g−1 at 1.0 A g−1). The presented findings offer the deep understanding of redox reactions and organic cathode evolution mechanisms for the progress of smarter energy storage batteries.

Numerical Design of Microporous Carbon Binder Domains Phase in Composite Cathodes for Lithium-Ion Batteries.

Lithium-ion battery (LIB) performance can be significantly affected by the nature of the complex electrode microstructure. The carbon binder domain (CBD) present in almost all LIB electrodes is used to enhance mechanical stability and facilitate electronic conduction, and understanding the CBD phase microstructure and how it affects the complex coupled transport processes is crucial to LIB performance optimization. In this work, the influence of microporosity in the CBD phase has been studied in detail for the first time, enabling insight into the relationships between the CBD microstructure and the battery performance. To investigate the effect of the CBD pore size distributions, a random field method is used to generate in silico a multiple-phase electrode structure, including bimodal pore size distributions seen in practice and microporous CBD with a tunable pore size and variable transport properties. The distribution of macropores and the microporous CBD phase substantially affected simulated battery performance, where battery specific capacity improved as the microporosity of the CBD phase increased.

Enhanced Electrochemical Performance of LiNi0.5Mn1.5O4 Composite Cathodes for Lithium-Ion Batteries by Selective Doping of K+/Cl- and K+/F.

K+/Cl− and K+/F− co-doped LiNi0.5Mn1.5O4 (LNMO) materials were successfully synthesized via a solid-state method. Structural characterization revealed that both K+/Cl− and K+/F− co-doping reduced the LixNi1−xO impurities and enlarged the lattice parameters compared to those of pure LNMO. Besides this, the K+/F− co-doping decreased the Mn3+ ion content, which could inhibit the Jahn–Teller distortion and was beneficial to the cycling performance. Furthermore, both the K+/Cl− and the K+/F− co-doping reduced the particle size and made the particles more uniform. The K+/Cl− co-doped particles possessed a similar octahedral structure to that of pure LNMO. In contrast, as the K+/F− co-doping amount increased, the crystal structure became a truncated octahedral shape. The Li+ diffusion coefficient calculated from the CV tests showed that both K+/Cl− and K+/F− co-doping facilitated Li+ diffusion in the LNMO. The impedance tests showed that the charge transfer resistances were reduced by the co-doping. These results indicated that both the K+/Cl− and the K+/F− co-doping stabilized the crystal structures, facilitated Li+ diffusion, modified the particle morphologies, and increased the electrochemical kinetics. Benefiting from the unique advantages of the co-doping, the K+/Cl− and K+/F− co-doped samples exhibited improved rate and cycling performances. The K+/Cl− co-doped Li0.97K0.03Ni0.5Mn1.5O3.97Cl0.03 (LNMO-KCl0.03) exhibited the best rate capability with discharge capacities of 116.1, 109.3, and 93.9 mAh g−1 at high C-rates of 5C, 7C, and 10C, respectively. Moreover, the K+/F− co-doped Li0.98K0.02Ni0.5Mn1.5O3.98F0.02 (LNMO-KF0.02) delivered excellent cycling stability, maintaining 85.8% of its initial discharge capacity after circulation for 500 cycles at 5C. Therefore, the K+/Cl− or K+/F− co-doping strategy proposed herein will play a significant role in the further construction of other high-voltage cathodes for high-energy LIBs.

A short investigation on LiMn2O4 wrapped with MWCNT as composite cathode for lithium-ion batteries

A short investigation on LiMn2O4 wrapped with MWCNT as composite cathode for lithium-ion batteries

PEDOT-PSS-Coated FeFe(CN)6 Composite Cathode for Lithium-Ion Batteries with the Improved Electrochemical Performances

Prussian-blue type FeFe(CN)6 nanocrystals with perfect nanocubic morphology were prepared by a facile hydrolytic precipitation method using Fe(CN)[Formula: see text] as a single iron-source. The resulting FeFe(CN)6 nanocrystals have subsequently been encapsulated within a mixed electronically and ionically conducting polystyrene sulfonic acid (PSS)-doped poly(3,4-ethylenedioxythiophene) (PEDOT) (PEDOT-PSS) with ethylene glycol (EG) as the polar solvent to obtain a high electrical conducting organic–inorganic nanohybrid. The FeFe(CN)6/PEDOT-PSS nanohybrid offers discharge capacity of [Formula: see text], which is improved compared to that of the naked FeFe(CN)[Formula: see text]. Also, it demonstrated the improved capacity retention and rate capability, which makes it a promising way for high performance Li-ion batteries for energy storage application.

Improved electrochemical performance of rare earth doped LiMn1.5-xNi0.5RExO4 based composite cathodes for lithium-ion batteries

Abstract LiMn1.5Ni0.5O4 with spinel type of structure was synthesized by sol-gel method and doped by different rare-earth elements (Nd, Gd and Dy). It was found that the inclusion of rare-earth element preserves the cubic spinel structure, leads to smaller particle size and improves the cyclic performance of the produced batteries. The best battery performance was obtained after doping the spinel structure by Gd. Among the used rare-earth elements Gd is the only one with stable oxidation state of 3 + which leads to stabilization of the Mn dissolution. Thus, the improvements observed in battery performance (rate performance and cycle life) are due to the superior structural stability of the doped active materials. It is concluded that the LiMn1.48Ni0.5Gd0.02O4 sample is the one with the best overall performance to act as active material for cathodes in rechargeable lithium-ion batteries.

A high voltage cathode prepared by using polyvinyl acetate as a binder

This paper describes the preparation and characterization of a high voltage composite cathode for lithium ion-batteries based on LiNi0.5Mn1.5O4 as the active material and poly vinyl acetate (PVAc) as the binder. To assess the effect of the PVAc binder on the electrode properties, the PVAc-based electrode is compared with a traditional one prepared by using Teflon as the binder. The electrode morphologies are investigated by scanning electron microscopy and the thermal behavior of the PVAc-based electrode evaluated by thermo gravimetry and differential thermal analysis. The distribution of oxygen, manganese, and nickel on the electrode is investigated by X-ray electron diffraction spectroscopy. The electrodes are used as cathodes to prepare lithium metal cells and their electrochemical properties are investigated through galvanostatic charge/discharge cycles conducted at various discharge currents.

Poly vinyl acetate used as a binder for the fabrication of a LiFePO4-based composite cathode for lithium-ion batteries

ABSTRACT This paper describes a method for the preparation of composite cathodes for lithium ion-batteries by using poly vinyl acetate (PVAc) as a binder. PVAc is a non-fluorinated water dispersible polymer commonly used in a large number of industrial applications. The main advantages for using of this polymer are related to its low cost and negligible toxicity. Furthermore, since the PVAc is water processable, its use allows to replace the organic solvent, employed to dissolve the fluorinated polymer normally used as a binder in lithium battery technology, with water. In such a way it is possible to decrease the hazardousness of the preparation process as well as the production costs of the electrodes. In the paper the preparation, characterization and electrochemical performance of a LiFePO 4 electrode based on PVAc as the binder is described. Furthermore, to assess the effect of the PVAc binder on the electrode properties, its performance is compared to that of a conventional electrode employing PVdF-HFP as a binder.

In-Situ Growth of LiMn2O4 Nanocrystals Embedded in Three-Dimension Single-Walled Carbon Nanotube Macrofilms as Stretchable Composite Cathode for Lithium-Ion Batteries

Electrode materials with total flexibility including not only the bendability but also the stretchability play the key roles in the emerging stretchable energy storage devices especially for the stretchable lithium-ion batteries (LIB). Herein, a stretchable composite for LIB cathode was fabricated by in-situ growth of LiMn2O4 (LMO) nanocrystals in the 3D macrofilms of single-walled carbon nanotube (SWNT) network via a low-temperature hydrothermal synthesis. Tomographic cross sections by focus ion beam (FIB) reveals the homogenous embedment of LMO nanocrystals spreading over the entire SWNT scaffold. X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM) have confirmed the strong chemical bonding between LMO and the carboxyl groups on activated CNT surface through the in-situ growth. Such intense interactions ensure the mechanical property and electrical conductivity inherited from SWNT. The as-prepared 3D composites could be laminated with elastomeric substrate such as polydimethylsiloxane (PDMS) to form stretchable cathodes with full flexibility. The electrochemical performance of the freestanding LMO-SWNT macrofilm composite has been evaluated by galvanostatic charge-discharge cycling measurements, cyclic voltammetry and electrochemical impedance spectroscopy in CR2032 coin-cell configuration with lithium metals. The capacity retention exhibits a decreasing specific discharge capacity from initial 120 mAhg-1 approaching more stable to 100 mAhg-1 at the rate of 0.1 C (~ 15 mAg-1) for over 250 cycles. Correspondingly the Coulombic efficiency starts increasing from about 70% to over 95% at the end of cycling. Then the potential intermittent titration technique (PITT) was employed to analyze the Li+ chemical diffusivity of the freestanding composite related to the electrochemical performance. This present work provides a necessarily preliminary examination on the feasibility of the stretchable cathode before developing the fully stretchable LIB in the future.

Aqueous Processing of LiNi0.5Mn0.3Co0.2O2 Composite Cathodes for Lithium-Ion Batteries

IntroductionRecently, there has been growing interest in switching fabrication of composite electrodes for lithium-ion batteries (LIBs) to aqueous systems due to advantages in low cost and environmental effect 1. Aqueous processing for conventional graphite anode is relatively mature, but remains challenging for the diverse array of LIB cathodes. Some success has been achieved on LiFePO4 2-4, LiCoO2 5 , LiNi1/3Mn1/3Co1/3O2 (NMC333) 6, lithium-and manganese-rich NMC 7. In this work, NMC532 cathodes were fabricated through aqueous processing with different water soluble binder and dried at various conditions. The effect of binders and residual moisture on the electrode performance was evaluated. Experimental NMC532 aqueous suspension was mixed with a planetary mixer and coated by a slot-die coater. The cathode consiss of 90wt% NMC532, 5 wt% Denka carbon black, 4 wt% water soluble binder, and 1 wt% carboxymethyl cellulose (CMC) as dispersant/binder. Four binders were investigated. Al current collected was treated by corona plasma for improved wettability of the aqueous suspension 8.The electrodes were also dried at various temperatures resulting in different residual moisture in the electrodes when being assembled into coin cells. Electrode performance was evaluated in both half and full coin cells. Half cells were assembled with NMC532 and Li metal as the cathodes and anodes, respectively. A12 graphite anode was selected as the anode in full cells. A Celgard 2325 separator was placed between the cathode and anode. The electrolyte was 1.2 M LiPF6in ethylene carbonate: diethyl carbonate (3/7 wt ratio). The cells were cycled between 2.5 and 4.2 V (VSP, BioLogic) for rate performance and cyclic performance. Results Figure 1 shows the NMC532 performance with various binders from half coin cells. They were similar at low C-rates and were better than that with PVDF from NMP-based processing at high C-rates. The one with latex also demonstrated identical cyclic performance to that with PVDF. This indicates comparable performance could be obtained on NMC532 from aqueous processing.Figure 2 shows the effect of drying temperature on discharge capacity of NMC. The various drying temperatures lead to different residual moisture. According to Figure 2, NMC532 dried at 120oC for 2 h showed the best performance. The residual moisture was 45 ppm at that condition. The drying condition is similar to that with conventional BMP-based processing. This indicates that it doesn’t require extra effort to remove residual moisture from electrode fabricated via aqueous processing. Aqueous processing of composite cathodes could provide comparable performance to those via conventional NMP-based processing. Acknowledgment This research at Oak Ridge National Laboratory (ORNL), managed by UT Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725, was sponsored by the Office of Energy Efficiency and Renewable Energy Vehicle Technologies Office (VTO) Applied Battery Research 9ABR) subprogram (Program Managers: Peter Faguy and David Howell). References (1) Li, J.; Daniel, C.; Wood, D. Journal of Power Sources 2011, 196, 2452.(2) Li, J.; Armstrong, B. L.; Daniel, C.; Kiggans, J.; Wood Iii, D. L. Journal of Colloid and Interface Science 2013, 405, 118.(3) Lee, J.-H.; Kim, J.-S.; Kim, C.; Zang, D. S.; Choi, Y.-M.; Park, W. I.; Paik, U. Electrochemical and Solid-State Letters 2008, 11, A175.(4) Li, C. C.; Peng, X. W.; Lee, J. T.; Wang, F. M. Journal of the Electrochemical Society 2010, 157, A517.(5) Li, C.-C.; Lee, J.-T.; Tung, Y.-L.; Yang, C.-R. Journal of Materials Science 2007, 42, 5773.(6) Loeffler, N.; von Zamory, J.; Laszczynski, N.; Doberdo, I.; Kim, G.-T.; Passerini, S. Journal of Power Sources 2014, 248, 915.(7) Wu, Q.; Ha, S.; Prakash, J.; Dees, D. W.; Lu, W. Electrochimica Acta 2013, 114, 1.(8) Li, J.; Rulison, C.; Kiggans, J.; Daniel, C.; Wood III, D. L. J. Electrochem. Soc. 2012, 159, A1152.

First-Principles Analysis of Phase Stability in Layered–Layered Composite Cathodes for Lithium-Ion Batteries

The atomic order in layered–layered composites with composition xLi2MnO3·(1 – x)LiCoO2 is investigated with first-principles calculations at the GGA+U level. This material, and others in its class, are often regarded as solid solutions; however, only a minute solubility of Li2MnO3 in a LiCoO2 host is predicted. Calculations of Co vacancy formation and migration energies in LiCoO2 are presented to elucidate the rate of vacancy-mediated ordering in the transition-metal-layer. The neutral Co vacancy formation energy is predicted to be in a range centered slightly above 1 eV but varies widely with the oxygen chemical potential. The calculated migration energy for the vacancy with charge q = −3e is approximately 1 eV. These values are small enough to be consistent with rapid ordering in the transition metal layer at typical synthesis temperatures and, therefore, separated Li2MnO3 and LiCoO2 phases. The relatively small (of the order of a few nm) Li2MnO3 domain sizes observed with TEM in some xLi2MnO3·(1 – x)LiMO2 composites may result from other factors, such as coherency strain, which perhaps block further domain coarsening in these materials.

Understanding the effect of synthesis temperature on the structural and electrochemical characteristics of layered-spinel composite cathodes for lithium-ion batteries

The effect of synthesis temperature on the structural and electrochemical characteristics of the layered-spinel composite cathode system xLi[Li0.2Mn0.6Ni0.2]O2–(1 − x)Li[Mn1.5Ni0.5]O4 (0 ≤ x ≤ 1) has been investigated. With a joint neutron diffraction (ND) and X-ray diffraction (XRD) Rietveld refinement method, the composition and weight percent variations of the layered and spinel phases in this composite cathode system have been obtained as a function of x and synthesis temperature. While no significant composition and weight percent variations are found with the synthesis temperature, the electrochemical characteristics of both the layered and spinel phases in the composites are significantly affected by the synthesis temperature. In contrast to the layered sample (x = 1), the capacity of the layered phase in the composites increases with decreasing synthesis temperature due to an increase in surface area. Conversely, the effect of synthesis temperature on the spinel phase is similar in both the spinel sample (x = 0) and the composite samples. However, the lower synthesis temperature increases the cation ordering in the 16d octahedral sites of the spinel phase, which changes the voltage profiles below 3 V due to the decrease in the lattice distortion during lithium ion insertion into the empty 16c octahedral sites.

Performance improvement on LiFePO4/C composite cathode for lithium-ion batteries

Temperature glycine assisted solid-state synthesis was used to prepare LiFePO4/C composite samples with two types of material improvements. It will be shown how can addition of a high conductive support as well as doping with supervalent metal ions improve the electrochemical performance of Li-ion cathode. Three samples with different properties were prepared and investigated – pure LiFePO4/C with no material improvements, LiFePO4/C prepared with multi walled carbon nanotubes (MWCNT) conductive support and LiFePO4/C doped by 1% of cobalt. Glycine was used as inorganic carbon coating precursor during the synthesis of all samples. XRD measurements confirmed production of highly crystalline LiFePO4 cathode material with diameter varying between 40 nm and 200 nm. Electrochemical measurements confirmed increasing the intra-particle conductivity by MWCNT or Co doping. Galvanostatic battery testing shows that LiFePO4/MWCNT/C composite delivers highest capacity 130 mA h g−1 at C/5. LiFePO4/MWCNT/C cathode material prepared by solid state synthesis exhibit excellent electrochemical performances, improved conductivity, and good rate capability compared to the LiFePO4/C composite material.

Preparation and Electrochemical Properties of LiFePO4-PSS Composite Cathode for Lithium-ion Batteries

In this study, we prepared <TEX>$LiFePO_4$</TEX>- poly (sodium 4-styrenesulfonate) (PSS) composite by the hydrothermal method and ball-milling process. Different wt% PSS were added to <TEX>$LiFePO_4$</TEX>. The cathode electrodes were made from mixtures of <TEX>$LiFePO_4$</TEX>-PSS: SP-270: PVDF in a weighting ratio of 70%: 25%: 5%. <TEX>$LiFePO_4$</TEX>-PSS powders were characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM). The electrochemical properties of <TEX>$LiFePO_4$</TEX>-PSS/Li batteries were analyzed by cyclic voltammetry, charge/discharge tests, and AC impedance spectroscopy. A Li/<TEX>$LiFePO_4$</TEX>-PSS battery with 4.75 wt% PSS shows the best electrochemical properties, with a discharge capacity of 128 mAh/g.

Poly(2,5‐dimercapto‐1,3,4‐thiadiazole) as a Cathode for Rechargeable Lithium Batteries with Dramatically Improved Performance

Organosulfur compounds with multiple thiol groups are promising for high gravimetric energy density electrochemical energy storage. We have synthesized a poly(2,5-dimercapto-1,3,4-thiadiazole) (PDMcT)/poly(3,4-ethylenedioxythiophene) (PEDOT) composite cathode for lithium-ion batteries with a new method and investigated its electrochemical behavior by charge/discharge cycles and cyclic voltammetry (CV) in an ether-based electrolyte. Based on a comparison of the electrochemical performance with a carbonate-based electrolyte, we found a much higher discharge capacity, but also a very attractive cycling performance of PDMcT by using a tetra(ethylene glycol) dimethyl ether (TEGDME)-based electrolyte. The first discharge capacity of the as-synthesized PDMcT/PEDOT composite approached 210 mAh g(-1) in the TEGDME-based electrolyte. CV results clearly show that the redox reactions of PDMcT are highly reversible in this TEGDME-based electrolyte. The reversible capacity remained around 120 mAh g(-1) after 20 charge/discharge cycles. With improved cycling performance and very low cost, PDMcT could become a very promising cathode material when combined with a TEGDME-based electrolyte. The poor capacity in the carbonate-based electrolyte is a consequence of the irreversible reaction of the DMcT monomer and dimer with the solvent, emphasizing the importance of electrolyte chemistry when studying molecular-based battery materials.

Synthesis of LiFePO4/C Composite Cathode for Lithium-Ion Batteries

Two types of samples of LiFePO4 cathode material for lithium ion batteries was synthesized by glycine assisted sintering in our laboratories. Different type of conductive carbon support was used during synthesis. Often used amorphous Super P carbon in the first sample was altered for multiwall carbon nanotubes in the second sample. Physical characterization by SEM, TEM, XRD and TGA was made and electrochemical characterization by CV, EIS, Rate capability and Charge-Discharge was performed. Good performance of LiFePO4/C composite cathode for lithium-ion batteries electrode was observed.

LiMnPO4/C Composite Cathodes for Lithium-Ion Batteries Prepared by a Combination of Spray Pyrolysis with Wet Ballmilling

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One-pot, glycine-assisted combustion synthesis and characterization of nanoporous LiFePO 4/C composite cathodes for lithium-ion batteries

Nanoporous LiFePO 4/C composite cathodes have been synthesized by a novel one-pot, glycine-assisted combustion (GAC) method in presence of 2 wt.% Super P carbon in both Ar and 90% Ar–10% H 2 atmospheres at 750 °C for a short time of 6 h. While the Ar atmosphere offers phase pure samples, the Ar–H 2 atmosphere leads to the formation of impurity phases as indicated by X-ray diffraction data. The combustion-initiated expulsion of gases aids the formation of a nanoporous LiFePO 4/C composite structure as evident from electron microscopic analysis, which could allow easy penetration of the electrolyte and realization of an electronic–ionic 3D network. The nanoporous LiFePO 4/C sample synthesized in Ar atmosphere exhibits a high discharge capacity of 160 mAh g −1 with 3% capacity fade in 50 cycles and high rate capability. With a short reaction time, the GAC method offers an energy efficient approach to synthesize high performance olivine LiFePO 4/C composite cathodes.

Effect of conducting additives on the properties of composite cathodes for lithium-ion batteries

In an attempt to achieve lithium-ion batteries with high rate capability, the effect of conducting additives with various shapes and contents on the physical and electrochemical performances was evaluated. Although the density of the cathode decreased upon the addition of the additives, the electrical conductivity and electrochemical performance were greatly improved. The composite cathodes with well-dispersed multi-walled carbon nanotubes (MWCNTs) exhibited excellent high rate capabilities and cyclabilities. In the case of cathode with 8 wt.% of MWCNTs (low density—LD), the highest discharge capacity of 136 mAh/g was obtained at 5 C-rate and capacity retention of 97% for 50 cycles was observed at 1 C-rate of discharge. The cathode with a mixture of 2 wt.% of Super P and 4 wt.% of MWCNTs (LD) also exhibits improved cycle performances. The volume changes in the charge and discharge processes were successfully controlled by the bundles distributed between the host particles.