Cathodes For Rechargeable Lithium-Ion Batteries Research Articles

A low-cost naphthaldiimide based organic cathode for rechargeable lithium-ion batteries.

Recently, the development of cathode materials is becoming an important issue for lithium-ion batteries (LIBs). Compared with inorganic cathodes, the organic cathodes are developing rapidly, ascribing to their distinct merits in light weight, low cost, massive organic resources and high capacity. In this paper, a cost-efficiency naphthaldiimide (NDI) based derivative, 2,7-bis(2-((2-hydroxyethyl) amino) ethyl) benzo[lmn] [3,8] phenanthroline-1,3,6,8(2H, 7H)-tetraone (NDI-NHOH), was used as organic cathode in LIBs. The NDI-NHOH was synthesized easily via one-step process, and it showed very high thermal stability. Through mixing NDI-NHOH with acetylene black and polyvinylidene fluoride (weight ratio of 6:3:1) as composite cathode in lithium-metal based LIBs, the NDI-NHOH presented versatile electrochemical properties. From cyclic voltammetry (CV) test, it exhibited two reversible peaks for oxidation and reduction in the first cycle, respectively. Notably, the oxidation and reduction peaks were located at 2.54, 3.22 and 2.14, 2.32V vs. Li+/Li, respectively. By employing NDI-NHOH as cathode, it demonstrated a specific capacity of about 80mAh g-1 in the range of 1.5-3.5 V, where the batteries retained a capacity retention of 50% over 20 cycles. According to the LIBs study, it suggests that the NDI-NHOH-based derivative shows a potentially promising candidate as efficient organic cathode materials for high-performance metal-ions batteries.

Redox of Dual-Radical Intermediates in a Methylene-Linked Covalent Triazine Framework for High-Performance Lithium-Ion Batteries.

Covalent triazine frameworks (CTFs) are promising electrodes for rechargeable batteries due to their adjustable structures, rich redox sites, and tunable porosity. However, the CTFs usually exhibit inferior electrochemical stability because of the inactivation of the unstable radical intermediates. Here, a methylene-linked CTF has been synthesized and evaluated as a cathode for rechargeable lithium-ion batteries. Electron paramagnetic resonance (EPR) and in situ Raman characterizations demonstrated that the redox activity and reversibility of α-C and triazine radical intermediates are essentially important for the charging/discharging process, which have been efficiently stabilized by the synergetic π conjugation and hindrance effect caused by the adjacent rigid triazine rings and benzene rings in the unique CTF-p framework. Additionally, the methylene groups provided extra redox-active sites. As a result, high capacity and cycling stability were achieved. This work inspires the rational modulation of the radical intermediates to enhance the electrochemical performance of organic electrode materials for the next-generation energy storage devices.

Degradation mechanism and performance enhancement strategies of LiNixCoyAl1−x−yO2 (x ≥ 0.8) cathodes for rechargeable lithium-ion batteries: a review

Layered structural LiNixCoyAl1−x−yO2 (NCA, x ≥ 0.8) cathodes have been regarded as one of the most promising cathode candidates for next-generation high-energy density lithium-ion batteries on account of their superior discharge capacity and low cost. Nonetheless, the structural and interfacial instability leads to their poor cyclability and inferior thermal stability, which needs to be urgently addressed prior to their further practical applications. In this review, we give a brief introduction about the degradation mechanism of layered NCA cathodes during charge-discharge processes and summarize proposed performance enhancement strategies, which may contribute to provide important ideas to design and construct integrated layered NCA cathodes for high-energy density lithium-ion batteries.

Highly Exfoliated and Functionalized Single-Walled Carbon Nanotubes as Fast-Charging, High-Capacity Cathodes for Rechargeable Lithium-Ion Batteries.

Compared with traditional metal-oxide lithium-ion battery (LIB) cathodes, nanocarbon-based cathode materials have received much attention for potential application in LIBs because of their superior power density and long-term cyclability. However, their lithium-ion storage capacity needs further improvement for practical applications, and the trade-off between capacity and conductivity, when oxygen functional groups as lithium-ion storage sites are introduced to the nanocarbon materials, needs to be addressed. Here, we report a sequential oxidation-reduction process for the synthesis of single-walled carbon nanotubes (SWCNTs) for LIB cathodes with fast charging, long-term cyclability, and high gravimetric capacity. A LIB cathode based on highly exfoliated (dbundle < 10 nm) and oxygen-functionalized single-walled carbon nanotubes is obtained via the modified Brodie's method using fuming nitric acid and a mild oxidant (B-SWCNTs). Post treatment including horn sonication and hydrogen thermal reduction developed surface defects and removed the unnecessary C-O groups, resulting in an increase in the Li-ion storage capacity. The B-SWCNTs exhibit a high reversible gravimetric capacity of 344 mA h g-1 at 0.1 A g-1 without noticeable capacity fading after 1000 cycles. Furthermore, it delivers a high gravimetric energy density of 797 W h kgelectrode-1 at a low gravimetric power density of 300 W kgelectrode-1 and retains its high gravimetric energy density of ∼100 W h kgelectrode-1 at a high gravimetric power of 105 W kgelectrode-1. These results suggest that the highly exfoliated, oxygen-functionalized single-walled carbon nanotubes can be applied to LIBs designed for high-rate operations and long cycling.

Nanonetwork-structured yolk-shell FeS2@C as high-performance cathode materials for Li-ion batteries

Pyrite FeS2 is a promising alternative to typical intercalation cathodes for rechargeable lithium-ion batteries (LIBs) by virtue of its extremely high theoretical capacity. However, the inferior rate capability and fast capacity degradation caused by the sluggish reaction kinetics and large volume expansion upon lithiation greatly hinder its practical application. Herein, a chemical crosslinking strategy is developed for the synthesis of the yolk-shell pyrite FeS2@porosity-rich sulfur-doped carbon nanonetworks (FeS2@C NNs) as cathode materials for high-performance LIBs. The 3D nanonetwork structure constructed by tight covalent connection of carbon shells can act as highways to facilitate the electron transport kinetics, while the well-orchestrated internal cavities of the yolk-shell nanostructure provide large void space to accommodate the volume expansion of pyrite FeS2. In addition, the porosity-rich characteristic of carbon shells ensures fast pathways for the Li+ diffusion across the shells. As a result, the yolk-shell FeS2@C nanonetworks exhibit excellent high-rate capability (353 mAh g−1 at 10 C) and exceptionally long lifespan of 1000 cycles with a high capacity of 435 mAh g−1 at a large current density of 5 C, which is by far the best of pyrite FeS2-based cathodes for LIBs.

Alternative Multifunctional Cyclic Organosilicon as an Efficient Electrolyte Additive for High Performance Lithium-Ion Batteries

Three kinds of functional organosilicons electrolyte additives, i. e. octamethylcyclotetrasiloxane (D4), octamethylcyclotetrasiloxane (OMCTS) and 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetra- siloxane (ViD4), are firstly used to produce high-performance LiNi0.6Co0.2Mn0.2O2 cathode for rechargeable Lithium-ion batteries (NCM622/Li half-cell) at a high potential. The electrochemical performance tests at 4.5V suggest that ViD4 is the most promising electrolyte additive than its counterparts. Moreover, the prepared NCM622/Li half-cell with 0.5wt.% ViD4 exhibits an improved energy density of 187.2mAhg−1 and a good discharge capacity retention of 83.6% at 1C rate after 150 cycles at 4.5V, which is relatively higher than that with D4 (81.3%), OMCTS (81.9%) and much better than the bare electrolyte (76.1%). The electrochemical characterizations, density functional theory calculation and surface analysis provide strong evidences that combined effects of the Si-O bond and vinyl functional group in ViD4 can promote the formation of a uniform cathode electrolyte interphase (CEI) film. Moreover, the ViD4-incorporated CEI film effectively enhances the interfacial stability between the NCM622 cathode and the electrolyte by suppressing the continuous decomposition of carbonate-based electrolyte and the exfoliation of these decomposition products. Hence, the ViD4-containing electrolyte shows a promising potential for the application in high energy density lithium-ion batteries.

Enhanced electrochemical performance of MoO3-coated LiMn2O4 cathode for rechargeable lithium-ion batteries

LiMn2O4 (LMO) spinel cathode materials are modified with MoO3 coating synthesized using a simple wet chemical method. The surface modified samples show much better capacity retention than pristine LMO. In specially, 3 wt% MoO3 coated sample (LMO/M3) exhibit superior rate specific capacity with 110, 90 and 75 mAhg−1 at 5, 7 and 10 C, respectively. In addition, after 900 cycles at a current of 2 C, a capacity retention of 69.1% was achieved for LMO/M3, which is higher than the 39.6% for the pristine LMO. The enhancements of the electrochemical performance can be largely attributed to the stabilization of the cathode structure by suppressing the manganese dissolution in the electrolyte and in favor for Li+ ion diffusion after MoO3 coating.

Flexible and Free-Standing Organic/Carbon Nanotubes Hybrid Films as Cathode for Rechargeable Lithium-Ion Batteries

Organic carbonyl compounds are promising electrode materials for high-performance lithium-ion batteries (LIBs), but generally suffer from poor cycling stability, low utilization, inferior rate performance, and relatively low reduction potential. In order to solve these problems, we report a dissolution-recrystallization method to prepare flexible, binder-free, and free-standing hybrid films of sodium 1,4-dioxonaphthalene-2-sulfonate and multiwalled carbon nanotubes (NQS/MWNTs) as high-performance cathode for rechargeable LIBs. The hybrid films demonstrate high utilization of NQS, stable cycling, and high-rate capability. The superior electrochemical performance is attributed to decreased size and high polarity of NQS, three-dimensional intertwined conductive network formed by MWNTs. Moreover, NQS/MWNTs show high initial reduction potential at 2.97 V, which is well explained via density functional theory (DFT) calculations. Meanwhile, the reversible redox mechanism of NQS/MWNTs during discharge/charge proc...

Effect of Side-Plane Width on Lithium-Ion Transportation in Additive-Free LiCoO2 Crystal Layer-Based Cathodes for Rechargeable Lithium-Ion Batteries

Rechargeable lithium-ion batteries (LIBs) with improved performance, including higher power, higher energy density, and superior cycling performance, are in demand for highly specialized applications. The design and synthesis of cathode materials with effective shapes surrounded by suitable faces for Li-ion transportation are essential for high-performance LIBs. In the present work, we address the effects of side-plane width on the Li-ion diffusion coefficient and charge transfer resistance of additive-free LiCoO2 electrodes composed of highly controlled crystals with exposed {101}, {012}, and {104} faces. The changes in the shape and order of orientation in the LiCoO2 crystals were evaluated using electron microscopic observations and X-ray diffraction measurements. The discharge capacity drastically increased from 87.9 to 131.5 mA·h·g–1 on increasing the width of the side plane in the LiCoO2 crystal from ca. 11 to ca. 59 nm. Further, electrochemical impedance spectroscopy revealed that the Li-ion diffus...

A high-rate and long cycling life cathode for rechargeable lithium-ion batteries: hollow LiNi0.5Mn0.5O2 nano/micro hierarchical microspheres

A rechargeable lithium-ion batteries cathode LiNi0.5Mn0.5O2 with hollow nano/micro hierarchical microspheres (LNMO-HS) is prepared. LNMO-HS with diameters of about 1μm is composed of approximately 100nm primary nanoparticles. The initial discharge capacity of LNMO-HS cathode is as high as 181.5mAhg−1 at 1C between 2.5 and 4.5V. The corresponding capacity retention is 96.3% during 100 charge and discharge cycles. The reversible discharge capacities are 152.2 (10C) and 134.6mAhg−1 (15C), respectively. After 1000 cycles at 15C, the capacity retention of LNMO-HS cathode is up to 95.5%. The superior rate capability and cyclability of LNMO-HS cathode can be attributed to the distinctive hollow nano/micro hierarchical microspherical structures. It could not only effectively reduce the paths of Li ions diffusion, increase contact area between electrodes and electrolyte but also buffer the volume changes during Li ions intercalation/deintercalation processes.

ZrO2-coated Li3V2(PO4)3/C nanocomposite: A high-voltage cathode for rechargeable lithium-ion batteries with remarkable cycling performance

In this study, we show that the poor cycling performance which seriously hinders the application of Li3V2(PO4)3/C for rechargeable lithium-ion batteries is overcome by amorphous ZrO2 nano-coating. The ZrO2-coated Li3V2(PO4)3/C was synthesized via a conventional solid-state method followed by the application of wet coating. The crystalline structure, morphology and electrochemical performance of the as-synthesized samples were investigated by XRD, SEM, TEM, EDS, galvanostatic charge/discharge and EIS measurements. Compared with the pristine Li3V2(PO4)3/C, the structure of ZrO2-coated Li3V2(PO4)3/C sample had no change, and the existence of ZrO2 nano-coating effectively enhanced the cycling performance. From the above results, it is believed that the improved cycling performance is attributed to the ability of ZrO2 layer in preventing direct contact of the active material with the electrolyte resulting in a decrease of electrolyte decomposition reactions.

Polypyrrole Coated LiMn0.15Fe0.85 PO4 Olivine As High Capacity Cathode Electrode for the Lithium-Ion Battery

Lithium iron phosphate has become the subject of great interest as storage cathodes for rechargeable lithium-ion batteries. Unfortunately, its intrinsic low electronic conductivity and low energy density still prevent it from practical commercialization [1]. In the past decade, Padhi et al [2] pioneered interest in the LiFe1-yMnyPO4 olivine system, showing the occupation of some percentage of octahedral 4c sites of LiFePO4 by Mn combines the advantages of the low toxicity of LiFePO4 and the relatively high operating voltage of LiMnPO4 (~4.1 V). This ability to increase the energy density of conventional LiFePO4 has been the driving force for extensive research on LiFe1-XMnxPO4 [3]. Nevertheless, besides the fundamentally low electronic conductivity of olivine, the Mn3+ doping may lead to another drawback, which is Mn3+ dissolution. It is generally accepted that Mn3+ causes serious mechanical stress and its disproportionation results in Mn2+dissolution from the surface by Jahn-Teller distortion [4]. Therefore, there have been many efforts to overcome these obstacles, for instance by decreasing the crystallite size and changing the morphology or providing a conductive matrix (e.g. carbon).In this work, we present the application of a composite LiMn0.15Fe0.85PO4 coated with conductive polypyrrole (PPy) as cathode electrode for the Li-ion battery. The effects of the PPy coating on the physicochemical and electrochemical properties have been extensively studied. SEM and TEM images show that the PPy is uniformly coated on the surface of LiMn0.15Fe0.85PO4. The LiMn0.15Fe0.85PO4 electrode with 9 wt. % PPy coating exhibits a high discharge capacity and good cycle life at room temperature. This electrode delivers a discharge capacity of 135 mAh/g at 1/2 C, and after 100 cycles, the discharge capacity still reaches 126 mAh/g. In contrast, the discharge capacity of the pristine LiMn0.15Fe0.85PO4 is only around 128 mAh/g under the same conditions, and 114 mAh/g remains after 100 cycles, as shown in Fig. 1a. Electrochemical impedance spectroscopy verified the improved electrochemical conductivity of LiMn0.15Fe0.85PO4/PPy electrode. In addition, analysis of the counter electrode (Li film) confirmed that the PPy coating can protect the electrode from HF attack, and thus lead to reduction of Mn3+ dissolution in the LiMn0.15Fe0.85PO4-PPy electrode (Fig. 1b).[1] A. Yamada, S. C. Chung, K. Hinokuma, Journal of the Electrochemical Society, 148 (2001) A224-A229.[2] A. K. Padhi, K. S. Nanjundaswamy, J. B. Goodenough, Journal of the Electrochemical Society, 144 (1997) 1188-1194.[3] S. Y. Chung, J. T. Bloking, Y. M. Chiang, Nat. Mater., 1 (2002) 123-128.[4] R. Von Hagen, H. Lorrmann, K. C. Möller, S. Mathur, Advanced Energy Materials, 2 (2012) 553-559.

Coating Effecrs on Li[Li1/9Ni1/3Mn5/9]O2 Cathodes for Rechargeable Lithium-Ion Batteries

not Available.

Synthesis and electrochemical performance of lithium vanadium oxide nanotubes as cathodes for rechargeable lithium-ion batteries

Abstract A new kind of cathode materials for rechargeable lithium-ion batteries, lithium vanadium oxide nanotubes synthesized by a combined sol–gel reaction and hydrothermal treatment procedure is reported in this paper. SEM, TEM, XRD and XPS techniques were performed to investigate the morphology and structure of the resulting materials. The results confirmed that the synthetic materials are composed of uniformly open-ended multiwalled nanotubes with a length from 1 to 3 μm. The inner and the outer diameters of the obtained nanotubes vary from 30 to 50 nm and 50 to 120 nm, respectively. The electrochemical performance as a cathode material was examined and evaluated by cyclic voltammetry, galvanostatic charge–discharge cycling and AC impedance spectroscopy techniques. The results indicated that the resultant lithium vanadium oxide nanotubes have a high initial discharge capacity of 457 mAh g−1 in the potential range of 1.0–4.0 V (vs. Li/Li+) and good cycling performance. The improved electrochemical performance of the products should be due to its special one-dimensional multiwalled tubular structure and the contribution of lithium-ions.

Nanocrystalline and long cycling LiMn2O4 cathode material derived by a solution combustion method for lithium ion batteries

A nanostructured LiMn2O4 spinel phase is used as a cathode for 4 V lithium batteries and is prepared by solution combustion synthesis using urea as a fuel. Lithium–manganese oxides have received more increasing attention in recent years as high-capacity intercalation cathodes for rechargeable lithium-ion batteries. Nanostructured electrodes have been shown to enhance the cell cyclability. For optimum synthesis, the spinel LiMn2O4 showed that the optimal heat treatment protocol was a 10 h calcination at 700 °C, which sustained 229 cycles between 3.0 and 4.3 V at a charge–discharge rate of 0.1 °C before reaching an 80% charge retention cut-off value. X-ray diffraction and electron diffraction pattern investigations demonstrate that all the LiMn2O4 products are a spinel phase crystal. TEM micrographs show the prepared products were highly crystalline with an average particle size of 20–50 nm. Cyclic voltammetry shows the absence of phase transitions in the samples ensures negligible strain, resulting in a longer cycle life. This work shows the feasibility of the solution combustion method for obtaining manganese oxides with nano-architecture and high cyclability, and suggests it is a promising method for providing small diffusion pathways that improve lithium-ion intercalation kinetics and minimize surface distortions during cycling.