Anodes For Rechargeable Lithium-ion Batteries Research Articles

Operando Stress Evolution in Hard Carbon Anodes – Insight into the Mechanical Degradation Induced Failure Mode in Rechargeable Sodium Ion Batteries

Microstructural instabilities in electrodes arising from cycling induced stress is a primary failure mode in rechargeable batteries. Therefore, a quantitative knowledge of the cycling induced stress evolution in rechargeable battery electrodes is important for understanding the electrode microstructural instabilities during cycling that can potentially inform the electrode design to prolong battery cycle life. The cycling induced stress in electrodes typically arises from the volume changes associated with insertion/extraction of the electroactive species in the electrode matrix. For example, operando measurement of lithiation-delithiation induced stress in graphite electrodes that typically show 10% volume change has previously resulted in useful information that correlates well with the lithiation-delithiation mechanism in graphite anodes1. The size of the shuttling-electroactive species can be taken as an indicator of the cycling induced stress magnitude that drives the electrode microstructural instabilities. In this regard, quantification of the cycling induced stress in rechargeable Na-ion battery electrodes is warranted for understanding mechanical degradation induced failure modes owing to the larger size of the electroactive species, i.e., Na ions (vs. Li-ion).Hard carbons as potential anodes in rechargeable sodium ion batteries has gained considerable attention in the recent past due to their superior Na-ion storage capability (vs. graphite that is a canonical anode in rechargeable lithium-ion batteries). However, hard carbon anodes typically show significant capacity fade that can potentially arise from cycling induced mechanical degradation of the anodes. Operando stress measurements coupled with comprehensive electrode microstructural characterization will provide valuable insights in this context. Here we report on the operando stress evolution in hard carbon anodes in rechargeable sodium ion batteries as probed by Multiple Optical-beam Sensing (MOS) technique that basically involves monitoring the spacings among a group of laser spot (Fig. 1). Preliminary measurements have shown that the stress correlates with the potential with a maximum around 12 MPa in compression during sodiation and tensile stress of ~ 2MPa during desodiation. Operando stress measurements are performed in hard carbon anodes in two different electrode configurations – typical composite anodes (with binder and conductive agents) and hard carbon thin film anodes (without binder and conductive agents). The thin film configuration is considered to evaluate intrinsic stress response in hard carbon anodes in absence of any secondary phase. A comparison of operando stress response in these two types of hard carbon anodes along with comprehensive electrode microstructural characterization will be presented. Additionally, attempts will be made to shed light on the current debate in the mechanism of sodium storage in hard carbon anodes by comparing operando stress response of hard carbons from multiple sources along with their structural characterization (Raman, XPS, surface area etc.). V. A. Sethuraman, N. Van Winkle, D. P. Abraham, A. F. Bower, and P. R. Guduru, Journal of Power Sources, 206, 334–342 (2012). Figure 1

A Review of Design Strategies in SiO/C Composite Anodes for Rechargeable Lithium-Ion Batteries.

Lithium-ion batteries (LIBs) are widely used in electric vehicles, portable electronic devices, clean energy storage, and other fields due to their long service life, high energy density, and low self-discharge rate, which also puts forward higher requirements for the performance of lithium-ion batteries. As an anode for lithium-ion batteries, SiO materials have garnered significant attention from researchers due to its high specific capacity (2400 mAh g-1), abundance of raw materials, and simple preparation. However, its large volume change (~200 %) and poor electrical conductivity hinder its large-scale commercial application. Researchers employ various methods to reduce the volume change of SiO during lithium intercalation and improve its structural stability during cycling. This work mainly reviews the chemical structure and lithium storage mechanism of SiO, as well as the latest research progress on the preparation methods of SiO/C anode materials, focusing on summarizing the following preparation strategies: chemical vapor deposition, mechanical ball milling, spray drying, and in-situ reduction/oxidation methods. The obtained SiO-based anode materials' structural characteristics and electrochemical properties are compared and summarized. Finally, this review discusses the advantages and disadvantages of the current preparation methods, the future research directions, and the development prospects of SiO-based anode materials.

Electrochemical Properties of Carbon Nanobeads and Mesophase-Pitch-Based Graphite Fibers as Anodes for Rechargeable Lithium-Ion Batteries

Various strategies have been devised to enhance the specific capacity (over 372 mA h g−1) and the cycle life of pure carbon-based anode materials for lithium-ion batteries (LIBs). Herein, we have prepared carbon nanobeads (CNBs) with inner onion-like carbon layer structures using chemical vapor deposition. Additionally, mesophase-pitch-based graphite fibers (MPGFs) were fabricated via the melt spinning method. MPGFs had a reversible capacity of 328.2 mA h g−1 with a steady Coulombic efficiency after 105 cycles (at 0.05 mA g−1). When cycled at 0.2 A g−1, the CNBs kept a reversible capacity of 586.2 mA h g−1 after 256 cycles with stable Coulombic efficiency. The onion-like carbon layer structures of CNBs were beneficial to the storage of lithium ions. In this work, CNBs were fabricated with inner onion-like carbon layer structures to enhance the electrochemical performance of LIBs.

Control of Nanoparticle Dispersion, SEI Composition, and Electrode Morphology Enable Long Cycle Life in High Silicon Content, Nanoparticle-Based Composite Anodes for Lithium-Ion Batteries

Striking a balance between high theoretical capacity, Earth abundance, and compatibility with existing manufacturing infrastructure, silicon is one of the few materials that meets the requirements for a next-generation anode for rechargeable lithium-ion batteries. Due to complications with extreme volume changes during charging/discharging and reactive interfacial chemistries, however, the cycle-life of silicon-based composite anodes is unacceptable for broad use. Developing a majority silicon composite anode formulation that overcomes these challenges and is compatible with current industry manufacturing practices requires materials and chemical engineering solutions that account for both electrode morphology and interfacial chemistry. Here, we synthesize surface-functionalized silicon nanocrystals that enable a highly dispersed and homogeneous slurry that can easily be integrated into standard electrode fabrication process. We use this formulation to print a 76 wt. % silicon composite electrode. We show that the contents and the morphology of the silicon electrolyte interphase – a determining factor in the cycle life of silicon-based anodes – can be controlled with a post-synthetic thermal curing procedure. When paired against a capacity-matched lithium nickel manganese cobalt oxide LiNi0.8Mn0.1Co0.1O2 cathode, the cell retains 72% of its capacity through 1000 charge/discharge cycles while delivering an initial anode specific capacity of nearly 1000 mAh/g and an areal capacity of 2.55 mAh/cm2. Figure 1

SnO2 -polypyrrole scaffolds as high capacity anodes for rechargeable lithium-ion batteries: A cooperative density functional theory and experimental investigation

Recently, porous architectures have received enormous attraction in the field of electrochemical energy storage and conversion devices, especially next-generation metal-ion batteries. In this regard, SnO2-Polypyrrole nanocomposite is synthesized by hydrothermal method and the porous scaffolds are fabricated by freeze-drying method. Structural analyses confirm the nanocomposite formation. Scanning electron microscope image shows spherical shape morphology for SnO2-Polypyrrole nanocomposite and porous structure for scaffolds. The Brunauer-Emmett-Teller measurement result validates the presence of micro and mesoporous on SnO2-PPy scaffold with a surface area of 6 m3g-1. The scaffold anode delivers the initial and first discharge capacity of 2201 mAh g−1 and 1304 mAh g−1 at 100 mA g−1 respectively. First principle density functional theory simulation is performed to calculate the Li adsorption on SnO2-Polypyrrole and pristine SnO2. The result reveals, a layer of lithium-ions being chemisorbed to the highly porous SnO2-Polypyrrole and responsible for high capacity. The porous architecture of SnO2-Polypyrrole, with high discharge capacity, turns out to be best possible anode material for lithium-ion battery.

Pyramid-Patterned Germanium Composite Film Anode for Rechargeable Lithium-Ion Batteries Prepared Using a One-Step Physical Method

Using a top-down magnetron sputtering technique with a high deposition-rate, a one-step method for preparing germanium (Ge) hybrid film is presented. At present, graphite film is used as a current collector because it is flexible, self lubricating, and possesses a stress–strain-relieving property. In order to further suppress the volume changes of the Ge, a multilayered electrically conductive nickel film is deposited between multilayered Ge films. The cells are cycled at a current density of 200 mA g−1. An initial discharge and charge capacity of 1180.7 and 949.3 mAh g−1 are achieved by the prepared integrated pyramid patterned Ge composite film anode, respectively. The average capacity was maintained at 580 mAh g−1 after 280 cycles. In the rate capability measurement, the Ge composite demonstrated a reversible capacity of 1163.1 mAh g−1. It is easily made using magnetron sputtering, which is widely accepted in the industry. A physical approach to increase pure Ge’s specific capacity and its cycle life for LIBs is demonstrated in this work.

Sno2 -Polypyrrole Scaffolds as High Capacity Anodes for Rechargeable Lithium-Ion Batteries: A Cooperative Density Functional Theory and Experimental Investigation

Sno2 -Polypyrrole Scaffolds as High Capacity Anodes for Rechargeable Lithium-Ion Batteries: A Cooperative Density Functional Theory and Experimental Investigation

Diverse-shaped tin dioxide nanoparticles within a plastic waste-derived three-dimensional porous carbon framework for super stable lithium-ion storage

Tin dioxides (SnO2) inserted into carbons to serve as anodes for rechargeable lithium-ion batteries are known to improve their cycling stability. However, studies on diverse-shaped SnO2 nanoparticles within a porous carbon matrix for super stable lithium-ion storage are rare. Herein, a hollow carbon sphere/porous carbon flake (HCS/PCF) framework is fabricated through template carbonization of plastic waste. By changing the doping mechanism and tuning the loading content, nano SnO2 spheres and cubes as well as bulk SnO2 flakes and blocks are in-situ grown within the HCS/PCF. Then, the as-prepared hybrids with built-in various morphological SnO2 nanoparticles serve as anodes towards advanced lithium-ion batteries. Notably, HCS/PCF embedded with nano SnO2 spheres and cubes anodes possess superb long-term cycling stability (~0.048% and ~0.05% average capacitance decay per cycle at 1 A/g over 400 cycles) with high reversible specific capacities of 0.45 and 0.498 Ah/g after 1000 cycles at 5 A/g. The ultra-stabilized Li+ storage is attributed to the effective mitigation of nano SnO2 spheres/cubes volume expansion, originating from the compact SnO2 yolk-HCS/PCF shell construction. This study paves a general strategy for disposing of polymeric waste to produce SnO2 core-carbon shell anodes for super stable lithium-ion storage.

Iron-graphene based anode material for rechargeable lithium-ion batteries decorated by gold nanoparticles recovered from gold plated waste surgical tools

A large amount of gold (Au) can be recycled from waste surgical tools, e.g., gold plated scissors, due to its rising demand and offers manufacturers an innovative opportunity from differentiation to the new and valuable product. In this research, we fabricated and designed an efficient method of gold nanoparticles (Au-NPs) incorporated with iron/graphene oxide (Fe2O3/GO) anode for rechargeable lithium-ion batteries (LIBs). Au nanoparticles were obtained by recycling waste surgical scissors whereas, Fe2O3/GO has been synthesized by mechanical alloying in a high-energy ball mill. The structure of the Au-Fe2O3/GO nanocomposite anode material was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). The electrochemical performance was determined at a constant current rate using a coin-type cell. The experimental results showed that the composite has a stable reversible capacity of about ∼980 mAh g−1 and was maintained for >200 cycles. The remarkable performance and improved lithiation/delithiation reactions were was contributed by highly dispersed spherical-shaped Au nanoparticles in the Fe2O3/GO matrix.

Lower-voltage plateau Zn-substituted Co3O4 submicron spheres anode for Li-ion half and full batteries

Carbonaceous materials are used as the anode for rechargeable lithium-ion batteries (LIBs), however, lithium dendrites are easily formed during cycling due to the low lithium insertion potential (~0.1 V versus Li+/Li). As alternative anodes, transition metal oxides based on conversion mechanism have attached much attention. But the high lithiation potential (>1.0 V vs. Li+/Li) usually leads to a low output voltage and energy density when used in a full cell configuration. Herein, Zn-substituted Co3O4 submicron spheres are successfully synthesized by a facile solvothermal reaction and subsequent calcination method. When used as the anode for LIB, the optimized sample shows a specific capacity of 686 mAh g−1 at 0.8 A g−1 after 500 cycles, and a specific capacity of 692.9 mAh g−1 at a higher current density of 3.2 A g−1 in a half-cell. Thanks to the controlled Zn substitution, the discharge voltage plateau is 0.16 V lower than that of the pure Co3O4 anode at a current density of 0.4 A g−1. Further investigation of the 0.5Zn-Co3O4//LiCoO2 full cells also displays a high capacity (400.7 mAh g−1 after 200 cycles at 0.4 A g−1) and an excellent rate capability (658.1 mAh g−1 at 1.6 A g−1) compared with the Co3O4//LiCoO2 full cells. This work confirms that substituting suitable metal elements into sub-micron conversion based anodes can reduce the voltage plateau, which is of great significance for the practical applications in high performance energy storage devices.

Characteristics and electrochemical performances of silicon/carbon nanofiber/graphene composite films as anode materials for binder-free lithium-ion batteries

We report the interfacial study of a silicon/carbon nanofiber/graphene composite as a potentially high-performance anode for rechargeable lithium-ion batteries (LIBs). Silicon nanoparticle (Si)/carbon nanofiber (CNF)/reduced graphene oxide (rGO) composite films were prepared by simple physical filtration and an environmentally-friendly thermal reduction treatment. The films were used as high-performance anode materials for self-supporting, binder-free LIBs. Reducing graphene oxide improves the electron conductivity and adjusts to the volume change during repeated charge/discharge processes. CNFs can help maintain the structural stability and prevent the peeling off of silicon nanoparticles from the electrodes. When the fabricated Si/CNF/rGO composites were used as anodes of LIBs, the initial specific capacity was measured to be 1894.54 mAh/g at a current density of 0.1 A/g. After 100 cycles, the reversible specific capacity was maintained at 964.68 mAh/g, and the coulombic efficiency could reach 93.8% at the same current density. The Si/CNF/rGO composite electrode exhibited a higher specific capacity and cycle stability than an Si/rGO composite electrode. The Si/CNF/rGO composite films can effectively accommodate and buffer changes in the volume of silicon nanoparticles, form a stable solid–electrolyte interface, improve the conductivity of the electrode, and provide a fast and efficient channel for electron and ion transport.

High-capacity CVD-grown Ge nanowire anodes for lithium-ion batteries: simple chemical etching approach for oxide removal

We demonstrated high-performance Ge nanowire (NWs) anodes for rechargeable lithium-ion batteries with high-capacity and high coulombic efficiency. The NWs were prepared using a simple chemical vapor deposition (CVD) method, which is favorable for the mass production of electrodes. The unstable oxides of Ge deteriorate the electrochemical characteristics of the batteries made from Ge-based anodes. To resolve the issue of the oxides and enhance the electrochemical performance, the oxides of the NWs were removed efficiently by a simple wet chemical etching method via a 10% HCl (aq) treatment. Transmission electron microscopy and energy-dispersive X-ray spectroscopy elemental mapping verified the removal of oxides. Charge and discharge capacity of the pristine NWs were 833.803 mAhg−1 and 650.63 mAhg−1 at first cycle. In comparison, the charge and discharge capacities after oxide removal were 1064.1 mAhg−1 and 905.6 mAhg−1 under the same conditions. The discharge capacity and coulombic efficiency of the oxide-removed NWs were 39.2% and 7.1% higher than those achieved without oxide removal. The coulombic efficiency of the oxide-removed NWs was higher than that of the pristine NWs (7.1% increase). The NWs were stable over 25 cycles at different C-rates. This approach provides an efficient and practical way to resolve the oxide issue of Ge-based anodes, and high-performance lithium-ion batteries were demonstrated using the oxide-removed NW anodes. This study presents an advance towards the realization of the commercial batteries based on Ge as an active electrode material.

Porous nanotube networks of SnO2/MoO3@Graphene as anodes for rechargeable lithium-ion batteries

We successfully fabricated composite porous nanotube networks of SnO2/MoO3@Graphene through electrospinning and used it as lithium-ion battery anodes. When the ratio of SnO2 to MoO3 is 1:1, the composite of SnO2/MoO3 delivers a high capacity of 560 mAh g−1 at 1 A g−1 after 300 cycles. The excellent electrochemical performance was attributed to the unique 3D porous nanotube network structure which could provide more transmission channels for Li+ ions and electrons, and provide more electrochemical reaction sites. The hybrid nanostructure can also weaken local stress and relieve volume expansion which contributes to the attractive cycling stability. Moreover, we added a small amount of graphene in the composite to improve the electrical conductivity, and the SnO2/MoO3@Graphene composite showed favorable electrochemical performance (798 mAh g−1 at 1 A g−1 after 300 cycles). Finally, electrospinning technology is a simple and efficient synthesis strategy, which can promote the preparation of different types of metal oxide composite materials and has good application prospects.

Understanding the high capacity contributions of Cu3PS4 towards lithium storage

A copper based phosphochalcogenide, Cu3PS4, is explored as an anode in rechargeable lithium-ion batteries. Li-ion storage performance is tested in half cell configuration in various potential windows and 0.01–3.0 V is found to yield very stable capacity values at high rates of discharge. Cu3PS4 delivers a capacity of ~970 mAh g−1 at a current density of 100 mA g−1 with ~165 mAh g−1 observed for 5000 cycles at 1000 mA g−1. The electrode can deliver a stable capacity of 225 mAh g−1 at 1000 mA g−1 after activation. The electrochemical performance is attributed to the presence of a polymeric film and conversion reaction which is probed by in situ Raman spectroscopy, infrared, and impedance measurements. The formation of a gel-like film on the electrode surface which induces a pseudocapacitive contribution is understood by ex-situ infrared (IR) spectroscopy and electron microscopy. Full cells with LiCoO2 cathode and Cu3PS4 anode are fabricated and observed to show stable capacity for a large number of cycles.

Enhancing cycle stability of Li metal anode by using polymer separators coated with Ti-containing solid electrolytes

The employment of lithium metal anode in rechargeable lithium batteries has been hindered by the safety concerns which are associated with the uncontrolled lithium dendrite growth and the unceasing side reactions with liquid electrolytes. In this work, we report that the use of Ti-containing solid electrolyte-coated separators can greatly enhance the cycle performances of lithium metal anode in cells using liquid electrolytes. The detailed morphologic studies indicate that more uniform lithium deposition is achieved in cells using Ti-containing solid electrolyte-coated separators than that using Al2O3-coated separators, which is likely due to the modified anode and electrolyte interfacial properties induced by the reactive nature of Ti-containing solid electrolytes with metallic lithium. This work demonstrates an effective strategy to enhance the homogeneity of lithium deposition, which leads to the stable cycling of lithium metal anode in rechargeable lithium-ion batteries. Texture intensity decreases by the increase in the amount of alloying elements

Effect of vacuum-carbonization treatment of soft carbon anodes derived from coal-based mesophase pitch for lithium-ion batteries

AbstractDevelopment of new power anode material with both high capacity and high-rate capability for lithium-ion batteries is highly desired. In this paper, a novel soft carbon anode for rechargeable lithium-ion batteries was developed using coal-based mesophase pitch. The structures of the materials were characterized by X-ray diffraction (XRD), Raman, N2 adsorption–desorption, Scanning Electron Microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The electrochemical characteristics of the new anode material were investigated. It was found that the soft carbon anode from coal-based mesophase pitch carbonized under vacuum conditions can deliver higher energy density and higher rate capability compared to soft carbon carbonized under a nitrogen atmosphere. The enhanced electrochemical properties are attributed to smaller nanocrystallites, more porosity, defects and carbon species of the resulting anode material.

ZnFe2O4/MoS2/rGO composite as an anode for rechargeable Lithium-ion batteries

The transition metal oxide ZnFe2O4 can be used as a promising anode material for lithium-ion batteries because of its higher theoretical capacity (1072 mA h g−1), and MoS2 has also received extensive attention because of its low cost and environmental friendliness. However, the expansion and contraction of the volume during charge and discharge limit the commercial application of ZnFe2O4 and MoS2. We synthesize ZnFe2O4/MoS2/reduced graphite oxide (ZnFe2O4/MoS2/rGO) ternary composite material by a simple two-step hydrothermal synthesis method and subsequent heat treatment. ZnFe2O4/MoS2/rGO displays a good electrochemical performance due to a synergistic effect of MoS2 with a three-dimensional spherical structure and rGO as a conductive agent. At a current density of 200 mA g−1, the discharge capacity still reaches 1568 mAh g−1 after 100 cycles. At the same time, high-rate performance is also good (638 mAh g−1 at 1800 mA g−1).

Microwave Synthesized TiP2O7/Carbon Composites for Use in Aqueous Lithium-Ion Batteries

Nowadays, Lithium ion batteries (LIBs) can be found in every corner of our daily life. However, safety and cost of lithium ion batteries are the two major issues. Aqueous rechargeable lithium ion batteries are believed to be the promising candidates for LIBs due to nonflammable，low cost higher ionic conductivity of aqueous electrolyte [1]. To reduce the cost of aqueous lithium-ion cells, researchers focus on developing methods to synthesize electrode material in an energy efficient way. It has been reported that TiP2O7 has a low intercalation /de-intercalation potential (2.6 V versus Li/Li+) [2], which makes it a promising anode material for aqueous lithium-ion batteries [3,4]. One report demonstrated a solid-state synthesis method annealing at 300◦C for 2 hours, annealing at 800◦C for 3 hours and cooling to room temperature for 4 hours [5]. The solid-state synthesis route is very common in industrial applications due to its simplicity. However, the long calcining duration and high temperature requirement increases the processing cost for the electrode materials. One report applied microwave to synthesize C-NaTi2(PO4)2, the negative electrode for aqueous sodium ion batteries [6]. Functional electrode materials can be synthesized in less than 20 minutes. In this work, a very fast microwave synthesis method was developed to produce C-TiP2O7 (Carbon and TiP2O7 Composite material). The precursor consists of (NH4)2HPO4 and anatase TiO2 in a molar ratio of 2:1, with 10wt%, 15wt% and 20wt%(the weight percent is relative to the precursor mixture) graphite added. After being ball milled together for 1 hour, the mixture was heated in a microwave oven (CEM Discover Proteomics System) for 10 minutes at 150W. The SEM figure shows the surface of Graphite-TiP2O7 composite, and the particle size of Graphite-TiP2O7 composite is around 40nm (Figure 1a). In XRD test (Figure 1b), the pattern of product matches with the reference pattern (JCPDS #38-1468) at major peaks (511), (600), (630), (721), (660), (933). The products we get from this method are tested in cyclic voltammetry tests, which shows promising electrochemical performance (Figure 2a); after ten cycles, the specific capacity of 10% Graphite-TiP2O7 composite maintains 107.4 mAh/g. (Figure 2b). Figure 1 a) SEM of Graphite-TiP2O7 composite. B) XRD patterns of Graphite-TiP2O7 composite and reference peaks. Figure 2 a) Second cycles of cyclic voltammetry curves of 10% Graphite-TiP2O7 composite, 15% Graphite-TiP2O7 composite and 20% Graphite-TiP2O7 composite in 1 M Li2SO4 at scan rate 0.5 mV/s in range of −0.5 V and −1.6 V versus MSE. b) Discharge cycling performance of Graphite-TiP2O7 composite. The total synthesis time is only 10 minutes for heating and 30 minutes for cooling, which is much less than for traditional solid state synthetic methods. Reference: Kim H, Hong J, Park K Y, et al. Aqueous Rechargeable Li and Na Ion Batteries[J]. Chemical Reviews, 2014, 114(23):11788.Aravindan V, Reddy M V, Madhavi S, et al. Hybrid supercapacitor with nano-TiP2O7, as intercalation electrode[J]. Journal of Power Sources, 2011, 196(20):8850-8854.Wang H, Huang K, Zeng Y, et al. Electrochemical properties of TiP2O7, and LiTi2(PO4)3, as anode material for lithium ion battery with aqueous solution electrolyte[J]. Electrochemical Acta, 2007, 52(9):3280-3285.Rai A K, Gim J, Song J, et al. Electrochemical and safety characteristics of TiP2O7 –graphene nanocomposite anode for rechargeable lithium-ion batteries[J]. Electrochemical Acta, 2012, 75(4):247-253.Wu W, Shanbhag S, Wise A, et al. High Performance TiP2O7 Based Intercalation Negative Electrode for Aqueous Lithium-Ion Batteries via a Facile Synthetic Route[J]. Journal of the Electrochemical Society, 2015, 162(9): A1921-A1926.Wu W, Mohamed A, Whitacre J F. Microwave Synthesized NaTi2(PO4)3 as an Aqueous Sodium-Ion Negative Electrode[J]. Journal of the Electrochemical Society, 2013, 160(3): A497-A504. Figure 1

Improvement on electrochemical performances of nanoporous titania as anode of lithium-ion batteries through annealing of pure titanium foils

The effect of annealing of Ti foils before anodization on the morphology and electrochemical performance of resultant nanoporous anatase TiO2 (np-TiO2) as anode in rechargeable lithium-ion batteries (LIBs) was investigated. The np-TiO2 anode fabricated from annealed Ti foils exhibited higher specific surface area and reduced pore diameter compared to np-TiO2 electrode fabricated from as-received Ti foils. The highly porous np-TiO2 anode fabricated from annealed Ti foils exhibited 1st discharge capacity of 453.25 mAh/g and reduced to 172.70 mAh/g at 1 C current rate after 300 cycles; whilst the np-TiO2 electrode fabricated from the as-received Ti foils exhibited 1st discharge capacity of 213.30 mAh/g and reduced to 160.0 mAh/g at 1 C current rate after 300 cycles. Even after 400 cycles, such np-TiO2 electrode exhibited a reversible capacity of 125.0 mAh/g at 2.5 C current rate. Compared to the untreated Ti foils, the enhanced electrochemical performance of np-TiO2 anode fabricated from annealed Ti foils was ascribed to the annealing-induced removal of residual stress among the Ti atoms. The benefit of annealing process can reduce pore size of as-fabricated np-TiO2.

Biomorphic template-engaged strategy towards porous zinc manganate micro-belts as a competitive anode for rechargeable lithium-ion batteries

A sustainable yet massive synthesis of porous micro-/nano-structured spinel mixed metal oxides is highly desirable as advanced anodes for their extensive applications in rechargeable lithium-ion batteries (LIBs). In this contribution, a self-sacrifice biomorphic template-engaged strategy was purposefully devised for efficient and scalable fabrication of hierarchical porous ZnMn2O4 micro-belts (ZMO-MB). The synthetic procedure mainly involves impregnating natural cotton fibers with Mn2+/Zn2+ ions, followed by sacrificing template over calcination in air. The underlying formation process of the ZMO-MB was rationally put forward with comparative analysis. Physicochemical investigations showed that the well-defined ZMO-MB with hierarchical meso-/macro-porosity was composed of assembled nanoparticle subunits. Taking advantages of intrinsic structural and functional merits, the resultant ZMO-MB with a mass loading of ∼1.2 mg exhibits appealing Li-storage properties with large reversible capacity (∼436 mAh g−1 at 2000 mA g−1), high initial Coulombic efficiency (∼71.2%) and appealing long-duration cyclability at high rates (∼731 mAh g−1 after 150 cycles at 500 mA g−1) when evaluated as a promising anode platform for high-performance LIBs. More encouragingly, we strongly envision that the smart electrode design concept here can be easily for large-scale production and engineering of promising ZMO for next-generation LIBs.