LiNi0.5Mn0.3Co0.2O2/Au nanocomposite thin film cathode with enhanced electrochemical properties (original) (raw)
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Properties of LiNi 0.8 Co 0.1 Mn 0.1 O 2 as a high energy cathode material for lithium-ion batteries
−Nickel-rich layered materials are prospective cathode materials for use in lithium-ion batteries due to their higher capacity and lower cost relative to LiCoO 2. In this work, spherical Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 precursors are successfully synthesized through a co-precipitation method. The synthetic conditions of the precursors-including the pH, stirring speed, molar ratio of NH 4 OH to transition metals and reaction temperature-are investigated in detail, and their variations have significant effects on the morphology, microstructure and tap-density of the prepared Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 precursors. LiNi 0.8 Co 0.1 Mn 0.1 O 2 is then prepared from these precursors through a reaction with 5% excess LiOH· H 2 O at various temperatures. The crystal structure, morphology and electrochemical properties of the Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 precursors and LiNi 0.8 Co 0.1 Mn 0.1 O 2 were investigated. In the voltage range from 3.0 to 4.3 V, LiNi 0.8 Co 0.1 Mn 0.1 O 2 exhibits an initial discharge capacity of 193.0 mAh g −1 at a 0.1 Crate. The cathode delivers an initial capacity of 170.4 mAh g −1 at a 1 Crate , and it retains 90.4% of its capacity after 100 cycles.
Journal of Power Sources, 2019
The targeted optimization of Li-ion batteries (LIBs) requires a fundamental understanding of the wide variety of interdependencies between electrode design and electrochemical performance. In the present study, the effects of thickness and porosity on the electrochemical performance and Li-ion insertion kinetics of LiNi 0.6 Co 0.2 Mn 0.2 O 2-based (NCM-622) cathodes are investigated. Cathodes of different thickness and porosity are prepared and analyzed regarding their rate capability. The polarization behavior is investigated using electrochemical impedance spectroscopy. A simple mathematical model is employed to estimate the impact of Li-ion diffusion limitations in the electrolyte. The results are considered at both, the materials and the full-cell level. The design parameters are found to have distinct impact on the electrolyte, contact and charge transfer resistance as well as the Li-ion diffusion limitations in the electrolyte, significantly influencing the rate capability. The results attest an inherent tradeoff between energy and power density. The insights of this study can be used straightforward for the optimization of gravimetric and volumetric energy density of LIBs depending on the desired application.
ChemElectroChem, 2015
An integrated layered-spinel LiNi 0.33 Mn 0.54 Co 0.13 O 2 was synthesized by self-combustion reaction (SCR), characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. It was studied as a cathode material for Li-ion batteries and its electrochemical performance was compared with that of the layered cathode materialLiNi 0.33 Mn 0.33 Co 0.33 O 2 being operated at a wide potential window. The Rietveld analysis of LiNi 0.33 Mn 0.54 Co 0.13 O 2 indicated the presence of monoclinic Li[Li 1/3 Mn 2/3 ]O 2 (31%) and rhombohedral (LiNi x Mn y Co z O 2 ) (62 %) phases as the major components, and spinel (LiNi 0.5 Mn 1.5 O 4 ) (7 %) as a minor component, which is well supported by TEM and electron diffraction. A discharge specific capacity of about 170 mAh g -1 is obtained in the potential range of 2.3-4.9 V vs. Li at low rate (C/10) with excellent capacity retention upon cycling. On the other hand, LiNi 0.33 Mn 0.33 Co 0.33 O 2 (NMC111) synthesized by SCR exhibits an initial discharge capacity of about 208 mAh g -1 in the potential range of 2.3-4.9 V, which decreases to a value of 130 mAh g -1 after only 50 cycles. In turn, the multiphase structure of LiNi 0.33 Mn 0.54 Co 0.13 O 2 seems to stabilize the behavior of this cathode material even when polarized to high potentials. LiNi 0.33 Mn 0.54 Co 0.13 O 2 shows superior retention of average discharge voltage upon cycling as compared to that of LiNi 0.33 Mn 0.33 Co 0.33 O 2 when cycled in a wide potential range. Overall, ChemElectroChem 10.1002/celc.201500339 2 LiNi 0.33 Mn 0.54 Co 0.13 O 2 can be considered as a promising low cobalt content cathode material for Li ion batteries.
Journal of The Electrochemical Society, 2007
The uniform and spherical LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles were successfully coated with AlF 3 . The structures and electrochemical properties of AlF 3 -coated LiNi 0.5 Co 0.2 Mn 0.3 O 2 were characterized by various techniques. When the coating amount was 0.5 mol%, the cathode showed enhanced cycling performance and rate capability compared to the pristine LiNi 0.5 Co 0.2 Mn 0.3 O 2 . The AlF 3 -coated LiNi 0.5 Co 0.2 Mn 0.3 O 2 /Li cell had capacity retention of 98% after 100 cycles even at 4 C over 2.8-4.5 V, while the pristine LiNi 0.5 Co 0.2 Mn 0.3 O 2 exhibited capacity retention of only 89%. Moreover, the rate capability and cyclic performance at elevated temperature (55 • C) were also improved. Electrochemical impedance spectroscopy testing revealed the improved electrochemical performance, which could be considered that the AlF 3 coating layer can suppress the increase of impedance during the charging and discharging process by preventing directly contact of the highly delithiated active material with electrolyte.
Fabrication of high power LiNi0.5Mn1.5O4 battery cathodes by nanostructuring of electrode materials
Using nanoparticles, instead of microparticles, as active electrode materials in lithium ion batteries could provide a solution to slow charging rates due to long ion diffusion pathways in conventional bulk materials. In this work, we present a new strategy for the synthesis of high purity lithium nickel manganese oxide (LiNi0.5Mn1.5O4) nanoparticles as a high-voltage cathode. A sonochemical reaction is used to synthesize nickel hydroxide and manganese dioxide nanoparticles followed by a solid-state reaction with lithium hydroxide. The product shows a single spinel phase and uniform spherical nano-particles under the appropriate calcination conditions. The LiNi0.5Mn1.5O4 exhibits a high voltage plateau at about 4.7–4.9 V in the charge/discharge process and delivers a discharge capacity of more than 140 mA h g−1 and excellent cycling performance with 99% capacity retention after 70 cycles. The synthesized nano-particles show improved electrochemical performance at high rates. This electrode delivers a power density as high as 26.1 kW kg−1 at a discharge rate of 40 C. This power performance is about one order of magnitude higher than traditional lithium ion batteries. These findings may lead to a new generation of high power lithium ion batteries that can be recharged in minutes instead of hours.
Metal oxide coatings can improve the electro-chemical stability of cathodes and hence, their cycle-life in rechargeable batteries. However, such coatings often impose an additional electrical and ionic transport resistance to cathode surfaces leading to poor charge−discharge capacity at high Crates. Here, a mixed oxide (Al 2 O 3) 1−x (Ga 2 O 3) x alloy coating, prepared via atomic layer deposition (ALD), on Li[Ni 0.5 Mn 0.3 Co 0.2 ]O 2 (NMC) cathodes is developed that has increased electron conductivity and demonstrated an improved rate performance in comparison to uncoated NMC. A " co-pulsing " ALD technique was used which allows intimate and controlled ternary mixing of deposited film to obtain nanometer-thick mixed oxide coatings. Co-pulsing allows for independent control over film composition and thickness in contrast to separate sequential pulsing of the metal sources. (Al 2 O 3) 1−x (Ga 2 O 3) x alloy coatings were demonstrated to improve the cycle life of the battery. Cycle tests show that increasing Al-content in alloy coatings increases capacity retention; whereas a mixture of compositions near (Al 2 O 3) 0.5 (Ga 2 O 3) 0.5 was found to produce the optimal rate performance.
Journal of Power Sources, 2018
Some scientific studies report that the use of nanosized cathode materials can improve the electrochemical performances of a battery. In fact, these materials can open new and important perspectives for cathode materials such as their use for power applications or for technologies for which an optimized interface with the electrolyte is required (e.g all solid state battery or polymer battery). However, the high scale production and the processing of these powders to obtain dense electrodes are difficult. In this study, submicronic particles of LiNi 1/ 3 Mn 1/3 Co 1/3 O 2 are synthesized using an easy and scalable coprecipitation synthesis protocol. Isolated particles of 200 nm are obtained and are fully characterized. The non-agglomerated morphology of this material improves the accessibility of the lithium insertion planes, and consequently, the high Crate behavior is clearly improved as compared to classic agglomerate materials. The difficult processing of submicronic particles is overcome thanks to an environmentally-friendly water-based formulation. Proof-of-concept Li-ion cells have been realized. Although submicronic particles are used, the cell is manufactured with a cathode loading of 18.8 mg cm −2 which is relevant for commercial application.