Electrochemical performance of Na0.6[Li0.2Ni0.2Mn0.6]O2 cathodes with high-working average voltage for Na-ion batteries (original) (raw)
Related papers
2017
Na0.6[Li0.2Ni0.2Mn0.6]O2 is synthesized by a self-combustion reaction (SCR) and studied for the first time as a cathodematerial for Na-ion batteries. The Na0.6[Li0.2Ni0.2Mn0.6]O2 cathode presents remarkable high rate capability and prolonged stability under galvanostatic cycling. A detailed analysis of X-ray diffraction (XRD) patterns at various states of cycling reveals that the excellent structural stability is due to a primarily solidsolution sodiation/desodiation mechanism of the material during cycling. Moreover, a meaningful comparison with Na0.6MnO2 and Na0.6[Li0.2Mn0.8]O2 reveals that the Na0.6[Li0.2Ni0.2Mn0.6]O2 cathode achieves a very high working-average voltage that outperforms most of the lithium-doped manganeseoxide cathodes published to date.
Journal of Alloys and Compounds, 2018
In a quest to produce cathode materials for lithium ion batteries that yield high capacities, the Li 1.2 Mn 0.6 Ni 0.2 O 2 , lithium-manganese rich cathode materials were synthesized via a facile one-pot co-precipitation process with various ratios of urea at pH 9.0, 9.5, 10.0 and 10.5. The physical properties of the cathode materials were analysed by X-ray diffraction, Brunauer-Emmett-Teller surface area, scanning electron microscopy, transmission electron microscopy, inductively coupled plasma mass spectrometry and energy dispersive spectroscopy. The X-ray diffraction study showed that the prepared materials were crystalline with an ordered layered structure in the respective unit cell parameters being indexed to a monoclinic C 2/c space group. Scanning electron microscopy showed that Li 1.2 Mn 0.6 Ni 0.2 O 2 particles are agglomerated, however pH 10.0 particles appear less agglomerated and possess a slightly higher surface area. The cathode materials were built into coin cells and displayed exceptional electrochemical performance in delivering more than 200 mAh g-1 at a constant current density of 20 mA g-1 in the voltage range of 2.0 V-4.8 V. In particular the cathode 2 material made at pH 10.0 delivered an initial high discharge capacity of 266 mAh g-1 at 20 mA g-1 current density and maintained a discharge capacity of more than 220 mAh g-1 at 50 mA g-1 after 50 cycles.
Improved Cycling Stability of Na-Doped Cathode Materials Li1.2Ni0.2Mn0.6O2 via a Facile Synthesis
ACS Sustainable Chemistry & Engineering, 2018
：Lithium-ion battery cathode materials Li 1.2-x Na x Ni 0.2 Mn 0.6 O 2 (x=0, 0.03, 0.05, 0.08, 0.10) were synthesized by introducing Na ions into the Li layer through a facile ball-milling method. XRD results reveal that the cathode materials Li 1.2-x Na x Ni 0.2 Mn 0.6 O 2 display a typical layered structure. The enlarged Li layer spacing was confirmed by the characterization of morphology and structure. The Li 1.12 Na 0.08 Ni 0.2 Mn 0.6 O 2 electrode shows an excellent electrochemical performance including high reversible discharge capacity (257 mAh g-1), enhanced rate capability (112 mAh g-1 at 5 C) and superior cycling stability (100% capacity retention after 50 cycles, 96% capacity retention after 100 cycles). The improved electrochemical performance of the Na-LNMO sample compared to the pristine LNMO sample mainly stems from the Na-doping which stabilizes the host layered structure by suppressing the phase transformation from layered to spinel structure during cycling. Moreover, the EIS results also confirm that Na-doping effectively decreases the charge transfer resistance and facilitates the Li diffusion of the as-prepared cathode material. This method provides novel insights into enhancing the electrochemical performance and preventing the high-performance layered electrode materials from structural degradation.
ACS Applied Materials & Interfaces, 2016
Li-and Mn-rich transition-metal oxides of layered structure are promising cathodes for Li-ion batteries because of their high capacity values, ≥250 mAh g −1. These cathodes suffer from capacity fading and discharge voltage decay upon prolonged cycling to potential higher than 4.5 V. Most of these Liand Mn-rich cathodes contain Ni in a 2+ oxidation state. The fine details of the composition of these materials may be critically important in determining their performance. In the present study, we used Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 as the reference cathode composition in which Mn ions are substituted by Ni ions so that their average oxidation state in Li 1.2 Ni 0.27 Mn 0.4 Co 0.13 O 2 could change from 2+ to 3+. Upon substitution of Mn with Ni, the specific capacity decreases but, in turn, an impressive stability was gained, about 95% capacity retention after 150 cycles, compared to 77% capacity retention for Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 cathodes when cycled at a C/5 rate. Also, a higher average discharge voltage of 3.7 V is obtained for Li 1.2 Ni 0.27 Mn 0.4 Co 0.13 O 2 cathodes, which decreases to 3.5 V after 150 cycles, while the voltage fading of cathodes comprising the reference material is more pronounced. The Li 1.2 Ni 0.27 Mn 0.4 Co 0.13 O 2 cathodes also demonstrate higher rate capability compared to the reference Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 cathodes. These results clearly indicate the importance of the fine composition of cathode materials containing the five elements Li, Mn, Ni, Co, and O. The present study should encourage rigorous optimization efforts related to the fine composition of these cathode materials, before external means such as doping and coating are applied.
Synthesis and electrochemical study of Li-Mn-Ni-O cathodes for lithium battery applications
Journal of Solid State Electrochemistry, 2003
Cathode powders of the Li -Mn -Ni -O system have been prepared at a ) ( Ni Mn Mn + ratio varying from 0 to 1. The solid state reaction method was used to obtain the cathode materials by mixing MnO 2 , LiCO 3 and NiO. A 20% excess of lithium was used in the precursors. The materials produced were examined by X-rays to identify their structure. Batteries were assembled by using these materials as cathode with a liquid electrolyte consisting of EC/DΜC 1:1, 1Μ LiPF 6 and Li anode. Their capacity, cycle fading and chargedischarge conditions were evaluated.
Crystal structure and size effects on the performance of Li[Ni1/3Co1/3Mn1/3]O2 cathodes
Journal of Materials Research, 2014
We have investigated the effects of crystal structure and size of Li[Ni 1/3 Co 1/3 Mn 1/3 ]O 2 (L333) cathodes on the performance of lithium-ion batteries. Cation ordering and particle sizes were determined as a function of annealing temperature with subsequent electrochemical performance monitored by cyclic voltammetry (CV) and charge-discharge testing. With increasing annealing temperature, L333 exhibits a greater cation ordering, which subsequently benefitted cell performance. However, higher annealing temperatures yielded larger crystal sizes, which resulted in a decrease in high rate discharge capacity and a significant capacity fade. This is attributed to an increase in lattice parameter and volume expansion during cycling, with the largest crystal sizes displaying the most significant structural changes due to the lower strain accommodation.
Advanced Functional Materials, 2021
A known strategy for improving the properties of layered oxide electrodes in sodium‐ion batteries is the partial substitution of transition metals by Li. Herein, the role of Li as a defect and its impact on sodium storage in P2‐Na0.67Mn0.6Ni0.2Li0.2O2 is discussed. In tandem with electrochemical studies, the electronic and atomic structure are studied using solid‐state NMR, operando XRD, and density functional theory (DFT). For the as‐synthesized material, Li is located in comparable amounts within the sodium and the transition metal oxide (TMO) layers. Desodiation leads to a redistribution of Li ions within the crystal lattice. During charging, Li ions from the Na layer first migrate to the TMO layer before reversing their course at low Na contents. There is little change in the lattice parameters during charging/discharging, indicating stabilization of the P2 structure. This leads to a solid‐solution type storage mechanism (sloping voltage profile) and hence excellent cycle life w...
Electrochimica Acta, 2013
Li[Li 0.2 Mn 0.56 Ni 0.16 Co 0.08 ]O 2 cathode materials with well-formed layered structure are synthesized by sol-gel process with different metal sources. Two normal metal salts (acetate and nitrate) are performed as the metal sources, and the effect of particle morphology on the electrochemical performance of the Li-rich layered oxide is investigated to show the importance of the choice of metal sources. Porosity with high specific surface area of 10.09 m 2 g −1 is only observed for the oxide powder synthesized with nitrate. Simultaneously, high discharge capacity of 247.8 mAh g −1 and 135.5 mAh g −1 are obtained at current densities of 200 mA g −1 and 2000 mA g −1 , respectively. In addition, the results of electrochemical impedance spectroscopy (EIS) indicate that such porous morphology with good particle contact can efficiently reduce the impedance of the oxide electrode.