Hard carbon/Li2.6Co0.4N composite anode materials for Li-ion batteries

Hard carbon/Li_2.6Co_0.4N composite anode electrode is prepared to reduce the initial high irreversible capacity of hard carbon, which hinders potential application of hard carbon in lithium ion batteries, by introducing Li_2.6Co_0.4N into hard carbon. Lithiated Li_2.6Co_0.4N provides the compensation of lithium in the first cycle, leading to a high initial coulombic efficiency of ca. 100% versus lithium. As-prepared hard carbon/Li_2.6Co_0.4N composite electrode presents initial capacity of 438 mA h g^− 1. A full cell using LiCoO₂ cathode and the composite anode shows much higher initial coulombic efficiency and capacity than those of a cell using LiCoO₂ and hard carbon anode. This paves the way to reduce the large initial irreversible capacity of hard carbon.     

Are transition-metal borides promising for Na ion batteries? A first-principles study on transition-metal boride monolayer

Although two-dimensional (2D) materials have been proposed as the promising candidates for Na ion batteries (NIBs), electrode materials with high specific capacity and moderate diffusion energy barriers are still scare. Here, we firstly demonstrated that transition-metal borides (TMB) are much more promising electrode materials than other transition metal compounds. Density functional theory (DFT) calculations are performed to investigate the electronic properties and Na storage capability of TMB monolayer, which is realized in recent experiments. TMB monolayer forms strong chemical interaction with Na atoms, and the diffusion energy barrier of Na atoms is much lower than LIBs. Importantly, TMB monolayer exhibits a very high Na storage capacity. Such exceptional properties, including high stoichiometry (namely TMBNa₂), excellent electronic conductivity, moderate Na diffusion and high operating voltage, endow TMB monolayers as very promising anode materials for NIBs.     

室温钠离子电池材料及器件研究进展

在众多电化学储能技术中,室温钠离子电池除具有能量密度高、循环寿命长的特点外,还具有其他电池体系所不具有的资源丰富和成本低廉的优势,是一种较理想的规模储能电池体系.中国科学院物理研究所自2011年以来致力于低成本、安全环保的钠离子电池技术的研发,在正、负极材料和电解质材料开发中取得了多项原创性的研究成果,并研制出Ah级钠离子软包电池.例如,首次发现Cu~(2+)/Cu~(3+)氧化还原电对高度可逆并设计了Na-Cu-Fe-Mn-O基低成本层状氧化物正极材料;首次通过简单的一步碳化法制备出性价比高的无烟煤基负极材料;首次将一种新型的钠盐NaFSI应用于碳酸酯非水电解质以大幅度提升电极材料的性能等.本文综述了物理所在钠离子电池材料及器件研究中所取得的重要进展和突破,期待经过进一步不懈地努力为实现钠离子电池的产业化做出重要贡献.     

Anionic redox reaction mechanism in Na-ion batteries

Na-ion batteries (NIBs), as one of the next-generation rechargeable battery systems, hold great potential in large-scale energy storage applications owing to the abundance and costeffectiveness of sodium resources. Despite the extensive exploration of electrode materials, the relatively low attainable capacity of NIBs hinders their practical application. In recent years, the anionic redox reaction (ARR) in NIBs has been emerging as a new paradigm to deliver extra capacity and thus offers an opportunity to break through the intrinsic energy density limit. In this review, the fundamental investigation of the ARR mechanism and the latest exploration of cathode materials are summarized, in order to highlight the significance of reversible anionic redox and suggest prospective developing directions.     

MgO-templated carbon as a negative electrode material for Na-ion capacitors

In this study, MgO-templated carbon with different pore structures was investigated as a negative electrode material for Na-ion capacitors. With increasing the Brunauer–Emmett–Teller surface area, the irreversible capacity increased, and the coulombic efficiency of the 1st cycle decreased because of the formation of solid electrolyte interface layers. MgO-templated carbon annealed at 1000 °C exhibited the highest capacity and best rate performance, suggesting that an appropriate balance between surface area and crystallinity is imperative for fast Na-ion storage, attributed to the storage mechanism: combination of non-faradaic electric double-layer capacitance and faradaic Na intercalation in the carbon layers. Finally, a Na-ion capacitor cell using MgO-templated carbon and activated carbon as the negative and positive electrodes, respectively, exhibited an energy density at high power density significantly greater than that exhibited by the cell using a commercial hard carbon negative electrode.     

Carbon-coated Si/graphite composites with combined electrochemical properties for high-energy-density lithium-ion batteries

Carbon-coated Si/graphite composites with different Si/graphite weight ratio have been fabricated using solid-state reaction with aim to improve the cyclic stability, coulombic efficiency, and rate capability simultaneously. Microstructural investigation reveals that the Si particles are covered by amorphous carbon and attached to the carbon-coated graphite surface. Electrochemical evaluation has been performed using cyclic voltammetry and charge/discharge cycling at different current densities, which indicate that addition of graphite can not only enhance the first-cycle coulombic efficiency to 90 % but also improve the cyclic stability drastically. The carbon-coated Si/graphite composite with appropriate contents of Si, graphite, and carbon is expected to be promising candidate as anode materials for high-energy-density lithium-ion batteries.     

Distinctive slit-shaped porous carbon encapsulating phosphorus as a promising anode material for lithium batteries

A distinctive structure of carbon materials for Li-ion batteries is proposed for the preparation of red phosphorus-carbon composites. The slit-shaped porous carbon is observed with aggregation of plate-like particles, whose isotherm belongs to the H3 of type IV. The density functional theory (DFT) method reveals the presence of micro-mesopores in the 0.5–5 nm size range. The unique size distribution plays an important role in adsorbing phosphorus and electrochemical performance. The phosphorus-slit-shaped porous carbon composite shows initial capacity of 2588 mAh g^?1, reversible capacity of 1359 mAh g^?1 at a current density of 100 mA g^?1. It shows an excellent coulombic efficiency of ～99 % after 50 cycles.     

A facile synthesis of heteroatom-doped carbon framework anchored with TiO<Subscript>2</Subscript> nanoparticles for high performance lithium ion battery anodes

Titanium dioxide (TiO₂)-based materials have been well studied because of the high safety and excellent cycling performance when employed as anode materials for lithium ion batteries (LIBs), whereas, the relatively low theoretical capacity (only 335 mAh g^?1) and serious kinetic problems such as poor electrical conductivity (~?10^?13S cm^?1) and low lithium diffusion coefficient (~?10^?9 to 10^?13 cm² s^?1) hinder the development of the TiO₂-based anode materials. To overcome these drawbacks, we present a facile strategy to synthesize N/S dual-doping carbon framework anchored with TiO₂ nanoparticles (NSC@TiO₂) as LIBs anode. Typically, TiO₂ nanoparticles are anchored into the porous graphene-based sheets with N, S dual doping feature, which is produced by carbonization and KOH activation process. The as-obtained NSC@TiO₂ electrode exhibits a high specific capacity of 250 mAh g^?1 with a coulombic efficiency of 99% after 500 cycles at 200 mA g^?1 and excellent rate performance, indicating its promising as anode material for LIBs.     

Morphology of carbon nanostructures and their electrochemical performance for lithium ion battery

A comparative study has been carried out on anodes made from carbon nanostructures of five different morphologies—single walled, double walled and multiwalled carbon nanotubes (with two different diameters), and carbon nanofibers. The specific area of the samples of these carbon nanostructures has been determined and their structure and morphology have been characterized by microscopy, X-ray diffraction and Raman spectroscopy. Depending on the morphology and the size of the nanostructures in the anode, the reversible capacity obtained ranges from 450 to 600 mAh g⁻¹ and the coulombic efficiency is in the range of 85–98% after 12 cycles. Increasing the surface area, both inside and outside for the tubes of a nano-size, gives rise to increased number of surface sites, which may be intercalated reversibly leading to increased specific charge capacity. Formation of the solid electrolyte interface layer covers a part of these surface sites as well as results in capacity fading, which also increases with increasing surface area. Increased defect sites responsible for elastic scattering in Raman spectra do not appear to have deciding influence on either enhanced capacity or capacity fading. Nano-sized constituent in the electrode appears to improve mechanical characteristics ensuring good mechanical integrity on cycling and high coulombic efficiency.     

Mg-doped layered oxide cathode for Na-ion batteries

Na-ion batteries (NIBs) are regarding as the optimum complement for Li-ion batteries along with the rapid development of stationary energy storage systems. In order to meet the commercial demands of cathodes for NIBs, O3-type Cu containing layered oxide Na_0.90Cu_0.22Fe_0.30Mn_0.48O₂ with good comprehensive performance and low-cost element components is very promising for the practical use. However, only part of the Cu³⁺/Cu²⁺ redox couple participated in the redox reaction, thus impairing the specific capacity of the cathode materials. Herein, Mg²⁺-doped O3-Na_0.90Mg_0.08Cu_0.22Fe_0.30Mn_0.40O₂ layered oxide without Mn³⁺ was synthesized successfully, which exhibited improved reversible specific capacity of 118 mAh/g in the voltage range of 2.4-4.0 V at 0.2 C, corresponding to the intercalation/deintercalation of 0.47 Na⁺ (0.1 more than that of Na_0.90Cu_0.22Fe_0.30Mn_0.48O₂). This work demonstrates an important strategy to obtain advanced layered oxide cathodes for NIBs.     

纳米储锂材料和锂离子电池

简单综述了锂离子电池的基本原理和发展现状，对中国科学院物理研究所固体离子学课题组在纳米储锂材料方面的研究进展做了介绍。用HRTEM等手段研究了纳米SnO、纳米Si以及纳米SnSb合金在Li入脱嵌过程中结构的变化。着重介绍了一种具有纳米微孔的球形硬碳材料和纳米SnSb合金钉扎的复合负极材料，在高功率密度和高能量密度锂离子电池方面具有广阔应用前景。     

Electrochemical performance of modified artificial graphite as anode material for lithium ion batteries

Artificial graphite anode material was modified by coating an amorphous carbon layer on the particle surface via a sol-gel and pyrolysis route. The electrochemical measurements demonstrate that appropriate carbon coating can increase the specific capacity and the initial coulombic efficiency of the graphite material, while excessive carbon coating leads to the decrease in specific capacity. Thick coating layer is obviously unfavorable for the lithium ion diffusion due to the increased diffusion distance, but the decreased specific surface area caused by carbon coating is beneficial to the decrease of initial irreversible capacity loss. The sample coated with 5 wt.% glucose exhibits a stable specific capacity of 340 mAhg^?1. Carbon coating can remarkably enhance the rate capability of the graphite anode material, which is mainly attributed to the increased diffusion coefficient of lithium ion.     

Chitosan: A N-doped carbon source of silicon-based anode material for lithium ion batteries

Silicon/graphite/carbon (Si/G/CTS-C) composite, based on nano-silicon, flake graphite, and chitosan-derived carbon (CTS-C), was prepared by spray drying and subsequent pyrolysis. The results of X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy illustrate that chitosan is a good dispersion agent and chitosan-derived carbon is N-doped. The results indicate that the initial charge capacity of Si/G/CTS-C composite is 613.9 mAh g^?1 at a current density of 100 mA g^?1 corresponding to an initial coulombic efficiency of 81.89%. Besides, the Si/G/CTS-C composite exhibits higher specific capacity, more superior rate capability, better cycling performance, and lower impedance than that of silicon/graphite/phenolic resin-derived carbon (Si/G/P-C) composite.     

A microporous carbon derived from phenol–melamine–formaldehyde resin by K2CO3 activation for lithium ion batteries

A microporous carbon material with large surface area was prepared by carbonizing and activating of phenol–melamine–formaldehyde resin, using K₂CO₃ as activation reagent. The textural characteristics of the carbon materials were characterized by scanning electron microscope, X-ray diffraction, Raman spectra, Brunauer–Emmett–Teller, elemental analyses, respectively. Results showed that the surface area and pore diameter of the activated carbon were 1,610 m² g^?1 and less than 2 nm. Electrochemical lithium insertion properties were also investigated. At a current density of 100 mA g^?1, the activated carbon showed an enormous first-discharge capacity of 2,610 mAh g^?1 and the first charge capacity of 992 mAh g^?1. From the second cycle, the coulombic efficiency went up rapidly to above 95 %. The results indicated it may be a promising candidate as an anode material for lithium secondary batteries.     

Development and characterization of a novel silicon-based glassy composite as an anode material for Li-ion batteries

A novel silicon-based glassy composite anode material with high initial coulombic efficiency and long cycling performance for lithium-ion batteries was synthesized by a wet mechanochemical reduction method. The in situ formed Si particles with size of 5-10 nm were uniformly distributed in the glassy matrices formed by B₂O₃ and P₂O₅. The as-prepared composite electrode revealed an initial charge and discharge capacity of 432.7 and 514.4 mAh g^− 1, respectively, with an initial coulombic efficiency of 84%. After 100 cycles, the reversible capacity retention rate was still up to 97%, meaning a favorable cycling stability.     

Liquid Crystalline Dispersions of Graphene‐Oxide‐Based Hybrids: A Practical Approach towards the Next Generation of 3D Isotropic Architectures for Energy Storage Applications

We report the use of the spray pyrolysis method to design self‐assembled isotropic ternary architectures made up of reduced graphene oxide (GO), functionalized multiwalled carbon nanotubes, and nickel oxide nanoparticles for cost‐effective high‐performance supercapacitor devices. Electrodes fabricated from this novel ternary system exhibit exceptionally high capacitance (2074 Fg^?1) due to the highly conductive network, synergistic link between GO and carbon nanotubes and achieving high surface area monodispersed NiO decorated rGO/CNTs composite employing the liquid crystallinity of GO dispersions. To further assess the practicality of this material for supercapacitor manufacture, we assembled an asymmetric supercapacitor device incorporating activated carbon as the anode. The asymmetric supercapacitor device showed remarkable capacity retention (>96%), high energy density (23 Wh kg^?1), and a coulombic efficiency of 99.5%.     

Fabrication of urchin-like NiCo<Subscript>2</Subscript>O<Subscript>4</Subscript> microspheres assembled by using SDS as soft template for anode materials of Lithium-ion batteries

In this paper, the urchin-like NiCo₂O₄ microspheres assembled by using sodium dodecyl sulfate (SDS) as soft template are successfully fabricated by a facile procedure including microemulsion-solvothermal reaction and subsequent calcination at 400 °C for 4 h. The structure and morphology of synthesized NiCo₂O₄ particles are investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It has been clearly revealed that the prepared three-dimensional urchin-like NiCo₂O₄ microspheres are constituted by one-dimension nanowires. As it is applied to anode for lithium-ion batteries (LIBs), the initial coulombic efficiency is up to 75.7%, and the specific reversible capacity retains up to 1034.2 mAh/g even after 40 cycles at a current density of 100 mA/g. Furthermore, as the current density gradually increases to 800 mA/g, it still delivers the reversible capacity of 895.4 mAh/g. The high reversible specific capacity, perfect cyclability, and rate performance are attributed to the unique urchin-like NiCo₂O₄ microspheres, which can alleviate the volume expansion and shorten the diffusion path of ions and electrons during lithiation/delithiation process. The self-standing urchin-like NiCo₂O₄ microspheres may be a very promising candidate in place of the commercial graphite-based anode materials for high-performance LIBs.     

Nanoporous carbon microspheres as anode material for enhanced capacity of lithium ion batteries

Nanoporous carbon microspheres (NCMs) are prepared by a one-step carbonizing and activating resorcinol?formaldehyde polymer spheres (RFs) in inert and CO₂ atmosphere for anode materials of lithium-ion batteries (LIBs). Compared with RFs carbon microspheres (RF-C), after activating with hot CO₂, the NCMs with porous structure and high BET surface area of 2798.8 m² g^?1, which provides abundant lithium-ion storage site as well as stable lithium-ion transport channel. When RF-C and NCM are used to anode material for LIBs, at the same current density of 210 mA g^?1, the initial specific discharge capacity are 482.4 and 2575.992 mA h g^?1, respectively; after 50 cycles, the maintain capacity are 429.379 and 926.654 mA h g^?1, respectively. The porous spherical structure of NCM possesses noticeably lithium-ion storage capability, which exhibits high discharge capacity and excellent cycling stability at different current density. The CO₂ activating carbonaceous materials used in anode materials can tremendously enhance the capacity storage, which provides a promising modification strategy to improve the storage capacity and cyclic stability of carbonaceous anode materials for LIBs.     

Facile preparation of SGC composite as anode for lithium-ion batteries

The silicon/graphite/carbon (SGC) composite was successfully prepared by ball-milling combined with pyrolysis technology using nanosilicon, graphite, and phenolic resin as raw materials. The structure and morphology of the as-prepared materials are characterized by X–ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscope (TEM). Meanwhile, the electrochemical performance is tested by constant current charge–discharge technique, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) measurements. The electrodes exhibit not only high initial specific capacity at a current density of 100 mA g^?1, but also good capacity retention in the following 50 cycles. The EIS results indicate that the electrodes show low charge transfer impedance R_sf?+?R_ct. The results promote the as-prepared SGC material as a promising anode for commercial use.     

ZnO nanoparticles anchored on nitrogen and sulfur co-doped graphene sheets for lithium-ion batteries applications

Herein, we demonstrate a facile one-step hydrothermal synthesis route to anchor ZnO nanoparticles on nitrogen and sulfur co-doped graphene sheets. The detailed material and electrochemical characterization have been carried out to demonstrate the potential of novel ZnO/NSG nanocomposite in Li-ion battery (LIBs) applications. The structure and morphology of nanocomposite were assessed by X-ray diffraction (XRD), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The as-synthesized ZnO/NSG nanocomposite has been studied as anode material in LIBs and delivered a high initial discharge capacity of 1723 mAh g^?1, at the current density of 200 mA g^?1. After 100 cycles, the ZnO/NSG nanocomposites demonstrated a high reversible capacity of 720 mAh g^?1 and coulombic efficiency of 99.8%, which can be attributed to the porous three-dimensional network, constructed by ZnO nanoparticles and nitrogen and sulfur co-doped graphene. Moreover, the designed nanocomposite has shown excellent rate capability and lower charge transfer resistance. These results are promising and encourage further research in the area of ZnO-based anodes for next-generation LIBs.