Papers by Keyword: Electrochemical Performance

Abstract: Transition metal phosphides (TMPs) are potential candidates for supercapacitors. To improve their performance by adjusting their morphology and composition, hierarchical CoP@NiMn-P nanocomposites were successfully prepared by the hydrothermal method, electrodeposition, and low-temperature phosphorization. NiMn-P nanosheets were coated on CoP nanowires to form a hierarchical structure. Electrochemical analysis results indicated that the specific capacitance reached 2162.2 F g^-1 at 1 A g^-1 with a high capacitance retention ratio of 83.3% after 5000 cycles at a current density of 10 A g^-1. This excellent electrochemical performance was attributed to the large specific surface area and enhanced conductivity. Furthermore, an asymmetric supercapacitor, CoP@NiMn-P//AC, was prepared using CoP@NiMn-P as the positive electrode and AC as the negative electrode. A large voltage window of 1.6 V and high energy density of 21.1 Wh kg^-1 at 804.3 W kg^-1 with a good capacity retention rate were achieved. The results confirm that CoP@NiMn-P has good potential for application in high-performance energy storage devices and provide a reference for the design of phosphide with morphology/composition optimization.

Abstract: Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ (L2MO) material coated with Li_1.3Al_0.3Ti_1.7(PO₄)₃(LATP) was synthesized by sol-gel method. The coating amount was 0%, 0.5%, 1%, 1.5%, 2%. It is found that LATP coating improves the cycle stability of the material. After 200 cycles at 0.6 C rate, the cycle retention rate of the uncoated sample is 72.7%, while the retention rate of sample with 1% coating amount reaches 85%. LATP coating improves the rate performance of the material. The sample with 1% coating amount has the best rate performance, and the discharge specific capacity is 71.5 mAh/g at 10 C rate, while the discharge specific capacity of the sample without coating is 60.1 mAh/g. LATP coating alleviates the side reaction between the material surface and the electrolyte. As a solid electrolyte, it promotes the transmission of Li⁺ and reduces the charge transfer impedance of the material. The thermal stability of these materials was tested by DSC. The results show that LATP coating could improve the thermal stability of the material in charged state.

Abstract: Li₄Ti₅O₁₂/SnO₂ composite with different SnO₂ contents were prepared by hydrothermal method. SnO₂ nanosheets were in situ formed on the surface of Li₄Ti₅O₁₂ nanoparticles. At the same time, Sn ions were doped into the Li₄Ti₅O₁₂ lattice, which effectively improved the conductivity of Li₄Ti₅O₁₂. When the content of SnO₂ was 8 %, the electrochemical performance of Li₄Ti₅O₁₂/SnO₂ composite was the best. The first discharge specific capacity was 480.54 mAh/g. The capacity remained at 276.8 mAh/g after 200 cycles at 0.1 A/g, and the capacity retention was as high as 87.4% (compared with the 10th cycle).

Abstract: The Li₄Ti₅O₁₂/Co₃O₄ composites were prepared by hydrothermal reaction method with different Co₃O₄ mass content (3%, 7%, 11%, and 15%). The Li₄Ti₅O₁₂ nanoparticles were set in-situ on the Co₃O₄ sheet. Co ion was doped into the Li₄Ti₅O₁₂ lattice. The first cycle specific capacity firstly increased and then decreased with Co₃O₄ content increasing, which the discharge capacity reached the peaking value that the first capacity was 1111 mAh/g and the specific discharge capacity retained 240 mAh/g after 200 cycles. After 200 cycles of charge and discharge, the retention of the capacity was 96.4% at 0.1 A/g, and the retention of the capacity was 98.4% at 0.5 A/g.

Abstract: The effect of Ti and Sb elements addition on the microstructures and corrosion resistance of hot-dip galvanized Zn-11Al-3Mg alloy was investigated by scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS), X-ray diffraction (XRD) and Electrochemical workstation, respectively. Results showed that the grain size of the alloy was obviously refined with the addition of Ti and Sb elements, due to Al₃Ti phase as the nucleation substrate resulted in the transformation of Al-rich phase from dendrite to petal-like. In addition, the pitting corrosion resistance of the alloy has been significantly enhanced.

Abstract: In order to increase the energy density of lithium-ion battery, the LiN_i0.8Co_0.1Mn_0.1O₂(NCM811) cathode material with higher Ni content has attracted much attention due to its advantages such as high energy density, low cost. However, there are some bottleneck problems about the NCM811 such as capacity fading, harsh storage conditions, poor thermal stability, poor safety, which limit its large-scale commercial use. This article reviews the urgent problems for NCM811 high nickel ternary materials, briefly describes several common synthesis methods, and focuses on the modification methods, such as element doping, surface coating and special core-shell structure for enhancing the electrochemical performances and explain the modification mechanism. Finally, we prospect the possible research development and commercial application of high nickel ternary material.

Abstract: In the present paper, a composite containing mixed oxides of tin and lead has been synthesized by the method of pulsed high-voltage discharge. Material was characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis and transmission electron microscopy. The composite consists of SnO₂ and PbO particles with an average size of ~350 nm, and SnPb₂O₄ nanowhiskers with size of 100 nm in diameter and few microns in length. The electrochemical performance of nanocomposite as a potential anode of lithium-ion battery has been investigated by the cyclic voltammetry and galvanostatic charge/discharge test in the potential range of 3.0–0.005 V. The reversible capacity of 821 mA·h/g was realized after 5-fold cycling at a current density of 100 mA/g. It was established that further cycling of the material is accompanied by a dramatic capacity fade: only 13 % of the initial capacity was obtained already after 10 cycles. The observed degradation in performance of nanocomposite results from its inability to compensate large lithiation/delithiation-induced volume expansion.

Abstract: LiV₃O₈ layered structure was successfully synthesized by a conventional solid-state approach and subsequent heat-treated at 400, 450, 500 and 550 oC. The samples were characterized by XRD, SEM, TEM, BET. Electrochemical performance of LiV₃O₈ was investigated by cyclic voltammetry (CV) and galvanostatic charge-discharge. The results showed that high purity of LiV₃O₈ with layered structure was formed. The morphology of the samples were mixed between nanorods and nanosheets structure. For electrochemical performance, results showed that LiV₃O₈ heat-treated at 500 oC performed a highest charge and discharge capacity of 212 and 172 mAh g^-1, respectively. From electrochemical performance results made them a good candidate for cathode material for lithium-ion batteries application.

Abstract: The CeO₂/rGO composites were prepared by hydrothermal method. The microscopic phase structure and microstructure of the samples were characterized by SEM, XRD and FTIR. The cyclic voltammetry (CV) and constant current charge and discharge tests were used to study the electrochemical stability and cycle ability of the CeO₂/rGO composite electrode. The results show that the incorporation of graphene effectively increases the reversibility of CeO₂ as an electrode material. The special structure of graphene provides a continuous network and more active sites for redox reactions. In the 6mol/L KOH electrolyte, the specific capacitance of CeO₂/rGO composite reached 114F·g^-1 when the current density was 0.5A/g. After 1000 cycles, the specific capacitance only decreased by 12.66%, which proves that this material has good cycle performance.

Abstract: Horse manure, organic waste from livestock, has been used for the production of nitrogen-doped porous carbons (NPC) which could be applied as functional material. The variety of different NH₄OH solution concentrations (0.5, 1, 1.5, 2 M) were introduced in hydrothermal treatment as activating agent. Also, the nitrogen precursor was served. Horse manure derived NPC were characterized through varied physicochemical properties including NPC yields, FTIR, SEM, XPS and N₂ sorption analyzer to characterize specific properties such as elemental composition on surface, surface functional bonding, physical morphology, and porosity of NPC. In addition, the incorporation of nitrogen dopant into the carbon was intended to further enhance the electrochemical performance.