Optimization of structural expansion and contraction for TiS2 by controlling the electrochemical window of intercalation/delithiation

The reversible layered structure of TiS2 with relaxation, such as a spring, was obtained by controlling the optimized potential range of 0.9-2.8 V (vs. Li+/Li) to yield high discharge capacity,...

Post-Synthetic and In Situ Vacancy Repairing of Iron Hexacyanoferrate Toward Highly Stable Cathodes for Sodium-Ion Batteries

Iron hexacyanoferrate (FeHCF) is a promising cathode material for sodium-ion batteries. However, FeHCF always suffers from a poor cycling stability, which is closely related to the abundant vacancy defects in its framework. Herein, post-synthetic and in-situ vacancy repairing strategies are proposed for the synthesis of high-quality FeHCF in a highly concentrated Na4Fe(CN)6 solution. Both the post-synthetic and in-situ vacancy repaired FeHCF products (FeHCF-P and FeHCF-I) show the significant decrease in the number of vacancy defects and the reinforced structure, which can suppress the side reactions and activate the capacity from low-spin Fe in FeHCF. In particular, FeHCF-P delivers a reversible discharge capacity of 131 mAh g−1 at 1 C and remains 109 mAh g−1 after 500 cycles, with a capacity retention of 83%. FeHCF-I can deliver a high discharge capacity of 158.5 mAh g−1 at 1 C. Even at 10 C, the FeHCF-I electrode still maintains a discharge specific capacity of 103 mAh g−1 and retains 75% after 800 cycles. This work provides a new vacancy repairing strategy for the solution synthesis of high-quality FeHCF.

The Effect of Annealing Temperature on the Synthesis of Nickel Ferrite Films as High-Capacity Anode Materials for Lithium Ion Batteries

Anode materials providing a high specific capacity with a high cycling performance are one of the key parameters for lithium ion batteries’ (LIBs) applications. Herein, a high-capacity NiFe2O4(NFO) film anode is prepared by E-beam evaporation, and the effect of the heat treatment is studied on the microstructure and electrochemical properties of LIBs. The NiFe2O4 film annealed at 800 °C (NFO-800) showed a highly crystallized structure and different surface morphologies when compared to the electrode annealed at a lower temperature (NFO-600, NFO-700). In the electrochemical measurements, the high specific capacity (1804 mA g−1) and capacity retention ratio (95%) after 100 cycles were also achieved by the NFO-800 electrode. The main reason for the good electrochemical performance of the NFO-800 electrode is a high structure integrity, which could improve the cycle stability with a high discharge capacity. The NiFe2O4 electrode with an annealing process could be further proposed as an alternative ferrite material.

MgCo layered double hydroxide-based yolk shell polyhedrons as multifunctional sulfur mediator for lithium-sulfur batteries

The development of efficient sulfur host materials to address the shuttle effect issues of lithium polysulfides (LiPSs) is crucial in the lithium-sulfur (Li-S) batteries, but still challenging. In the present study, a novel yolk shell structured MgCo-LDH/ZIF-67 composite is designed as Li-S battery cathode. In this composite, the shell layer is MgCo layered double hydroxide constructed by partially etching ZIF-67 nanoparticle by Mg2+, and the core is the unreacted ZIF-67 particle. The unique yolk shell structure not only provides abundant pores for sulfur accommodation, but also facilitates the electrolyte penetration and ion transport. The ZIF-67 core exhibits strong polar adsorption to LiPSs through the Lewis acid-base interactions, and the micropores/mesoporous can further trap LiPSs. Meanwhile, the MgCo-LDH shell exposes enough sulfur-philic sites for enhancing chemisorption and catalyzes the LiPSs conversion. As a result, when MgCo-LDH/ZIF-67 is used as sulfur host in the cathode, the cell achieves a high discharge capacity of 1121 mAh g-1 at 0.2 C, and an areal capacity of 5.0 mAh cm-2 under the high sulfur loading of 5.8 mg cm-2. The S/MgCo-LDH/ZIF-67 electrode holds a promising potential for the development of Li-S batteries.

Nanocrystalline Cellulose Supported MnO2 Composite Materials for High-Performance Lithium-Ion Batteries

The rate capability and poor cycling stability of lithium-ion batteries (LIBs) are predominantly caused by the large volume expansion upon cycling and poor electrical conductivity of manganese dioxide (MnO2), which also exhibits the highest theoretical capacity among manganese oxides. In this study, a nanocomposite of nanosized MnO2 and pyrolyzed nanocrystalline cellulose (CNC) was prepared with high electrical conductivity to enhance the electrochemical performance of LIBs. The nanocomposite electrode showed an initial discharge capacity of 1302 mAh g−1 at 100 mA g−1 and exhibited a high discharge capacity of 305 mAh g−1 after 1000 cycles. Moreover, the MnO2-CNC nanocomposite delivered a good rate capability of up to 10 A g−1 and accommodated the large volume change upon repeated cycling tests.

Synergistic Effect of Cation and Anion for Low-Temperature Aqueous Zinc-Ion Battery

Although aqueous zinc-ion batteries have gained great development due to their many merits, the frozen aqueous electrolyte hinders their practical application at low temperature conditions. Here, the synergistic effect of cation and anion to break the hydrogen-bonds network of original water molecules is demonstrated by multi-perspective characterization. Then, an aqueous-salt hydrates deep eutectic solvent of 3.5 M Mg(ClO4)2 + 1 M Zn(ClO4)2 is proposed and displays an ultralow freezing point of − 121 °C. A high ionic conductivity of 1.41 mS cm−1 and low viscosity of 22.9 mPa s at − 70 °C imply a fast ions transport behavior of this electrolyte. With the benefits of the low-temperature electrolyte, the fabricated Zn||Pyrene-4,5,9,10-tetraone (PTO) and Zn||Phenazine (PNZ) batteries exhibit satisfactory low-temperature performance. For example, Zn||PTO battery shows a high discharge capacity of 101.5 mAh g−1 at 0.5 C (200 mA g−1) and 71 mAh g−1 at 3 C (1.2 A g−1) when the temperature drops to − 70 °C. This work provides an unique view to design anti-freezing aqueous electrolyte."Image missing"

Advanced Current Collectors with Carbon Nanofoams for Electrochemically Stable Lithium—Sulfur Cells

An inexpensive sulfur cathode with the highest possible charge storage capacity is attractive for the design of lithium-ion batteries with a high energy density and low cost. To promote existing lithium–sulfur battery technologies in the current energy storage market, it is critical to increase the electrochemical stability of the conversion-type sulfur cathode. Here, we present the adoption of a carbon nanofoam as an advanced current collector for the lithium–sulfur battery cathode. The carbon nanofoam has a conductive and tortuous network, which improves the conductivity of the sulfur cathode and reduces the loss of active material. The carbon nanofoam cathode thus enables the development of a high-loading sulfur cathode (4.8 mg cm−2) with a high discharge capacity that approaches 500 mA·h g−1 at the C/10 rate and an excellent cycle stability that achieves 90% capacity retention over 100 cycles. After adopting such an optimal cathode configuration, we superficially coat the carbon nanofoam with graphene and molybdenum disulfide (MoS2) to amplify the fast charge transfer and strong polysulfide-trapping capabilities, respectively. The highest charge storage capacity realized by the graphene-coated carbon nanofoam is 672 mA·h g−1 at the C/10 rate. The MoS2-coated carbon nanofoam features high electrochemical utilization attaining the high discharge capacity of 633 mA·h g−1 at the C/10 rate and stable cyclability featuring a capacity retention approaching 90%.

Enhanced electrochemical performance of RuO2 doped LiNi1/3Mn1/3Co1/3O2 cathode material for Lithium-ion battery

LiNi1/3Mn1/3Co1/3O2 as a promising cathode material for lithium-ion batteries was synthesized by a sol-gel method using nitrate precursor calcined at 800°C for 10 hours. The crystallite nature of samples is confirmed from X-ray diffraction analysis. SEM and TEM analyses were used to investigate the surface morphology of the prepared samples. It was found that, highly crystalline polyhedral RuO2 nanoparticles are well doped on the surface of pristine LiNi1/3Mn1/3Co1/3O2 with a size of about approximately 200 nm. The chemical composition of the prepared samples was characterized by EDX and XPS analyses. The electrochemical performance of the proposed material was studied by cyclic voltammetry and charge/discharge analyses. The electrode kinetics of the samples was studied by electrochemical impedance spectroscopy. The developed RuO2 doping may provide an effective strategy to design and synthesize the advanced electrode materials for lithium ion batteries. The doping strategy has dramatically increased the capacity retention from 74 % to 90% with a high discharge capacity of 251.2 mAhg− 1. 3 % RuO2-doped LiNi1/3Mn1/3Co1/3O2 cathode materials have showed the similar characteristics of two potential plateaus obtained at 2.8 and 4.2 V compared with un doped electrode cathode material. These results revealed the enhanced performance of RuO2- doped LiNi1/3Mn1/3Co1/3O2 during insertion and extraction of lithium ions compared to pristine material.

Synthesis of Li4Ti5O12/V2O5 Nanocomposites for Lithium-ion Batteries by a One-pot co-precipitation Method

Li4Ti5O12/V2O5 nanocomposites were synthesized by a one-pot co-precipitation method. The structure and morphology of the as-prepared materials were analyzed by X-ray diffraction and transmission electron microscopy. The results show that Li4Ti5O12/V2O5 composites with different nano size were successfully synthesized. The Li4Ti5O12/V2O5 sample (2 wt.% V2O5 addition of Li4Ti5O12) keep at a high discharge capacity of 169.9 mAh g− 1 after 150 cycles at 1 C. The existence of the V2O5 reduces the size of Li4Ti5O12, which improve the electrochemical activity of the sample.

CaF2 Coated Li1.2Mn0.56Ni0.16Co0.08O2 Microspheres with Enhanced Electrochemical Performances as Lithium Ion Battery Cathode

Surface modification has been one of most effective methods to improve the electrochemical performance of lithium rich layered oxides. In this paper, the Li1.2Mn0.56Ni0.16Co0.08O2 microspheres are prepared by urea assisted combustion route, and then coated with proper amount of CaF2. XRD and SEM results show surface modification has not changed the structure of Li1.2Mn0.56Ni0.16Co0.08O2, and a uniform coating layer can be obtained. As lithium ion battery cathode, the optimal CaF2 (i.e, 2wt%) coated sample presents a high initial discharge capacity of 223 mAh·g-1 with Coulombic efficiency of 80.5% at 0.1C, which is much better than that of pristine sample. Also, a high discharge capacity of 119 mAh·g-1 can be obtained for CaF2 coated sample at 5C. The improved electrochemical performance may be attributed the formation of fast Li ion conductor on the surface supported by EIS study.