Old-loofah-derived hard carbon for long cyclicity anode in sodium ion battery

Hard carbon was prepared via the carbonization of the old loofah sponge at 800 °C for 1 h in the inert N₂ atmosphere for sodium ion battery (SIB) anode. The resultant old-loofah-derived hard carbon was investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Raman, galvanostatic charge/discharge, cyclic voltammetry (CV) and alternating current (AC) impedance. The results suggested that the old-loofah-derived hard carbon powders consisted of many irregular micro-particles with the mean particle size of 12 μm. Furthermore, the old-loofah-derived hard carbon anode also delivered satisfactory electrochemical performances in SIB. For example, the initial discharge specific capacity was as high as about 695 mAh g^?1 at 25 mA g^?1, and the reversible discharge specific capability after 1000 cycles was still about 171 mAh g^?1 even at 1000 mA g^?1, indicating long cycle stability and the promising feasibility of the old-loofah-derived hard carbon anode. The disordered micro-structure and large interlayer distance may jointly contribute into the satisfactory electrochemical performances.     

TiF3 catalyzed MgH2 as a Li/Na ion battery anode

MgH₂ has been considered as a potential anode material for Li ion batteries due to its low cost and high theoretical capacity. However, it suffers from low electronic conductivity and slow kinetics for hydrogen sorption at room temperature that results in poor reversibility, cycling stability and rate capability for Li ion storage. This work presents a MgH₂–TiF₃@CNT based Li ion battery anode manufactured via a conventional slurry based method. Working with a liquid electrolyte at room temperature, it achieves a high capacity retention of 543 mAh g^?1 in 70 cycles at 0.2 C and an improved rate capability, thanks to the improved hydrogen sorption kinetics with the presence of catalytic TiF₃. Meanwhile, the first realization of Na ion uptake in MgH₂ has been evidenced in experiments.     

Synthesis of SnO2/C anode for lithium ion battery by a reflux-assisted hydrothermal method

以氯化亚锡(SnCl₂·2H₂O)及聚乙烯吡咯烷酮(polyvinylpyrrolidone,PVP)为原料,通过回流辅助水热法制备了SnO₂/C复合材料并将其用作锂离子电池负极材料.采用X射线衍射仪(XRD),扫描电子显微镜(SEM)和透射电子显微镜(TEM)分析材料的结构和形貌;用恒流充放电,交流阻抗(EIS)和循环伏安(CV)对复合材料作为锂离子电池负极材料的电化学性能进行表征.所制备的复合材料中,纳米SnO₂晶粒(5~10 nm)均匀分散在由PVP热解形成的无定形碳中.电化学性能测试表明,该复合材料100次循环后,可逆容量为591.7 mA·h/g,呈现较好的循环性能.优异的电化学性能主要归因于纳米SnO₂颗粒在无定形碳基体中均匀分散及无定形碳对锡颗粒体积变化的有效缓冲.     

Titanium-based materials as anode materials for sodium ion batteries

钛基材料具有环境友好、安全性好、稳定性好等优点而备受关注。但是钛基材料带隙宽,电子导电性差,比容量低限制了其在钠离子电池领域的发展与应用。本文主要综述了TiO2、Na2TinO2n+1、NaTi2(PO4)3三类钛基材料的结构、电化学性能、改性方法和相关储钠机理。评述了钛基材料存在的问题并展望了其发展前景。今后的研究可以从以下几方面开展：① 深入研究钛基负极材料储钠机理;② 研究多种阳、阴离子掺杂对钛基材料的电子结构的影响,从根本上提高钛基材料的电子导电性;③ 与高比容量负极材料复合,获得兼具稳定性与高比容量优点的复合材料;④ 设计合成具有多级、三维结构的钛基复合负极材料,进一步提高材料的循环稳定性、倍率性能;⑤ 开发新型结构的钛基负极材料。     

Technology review of anode materials for lithium ion batteries

本文综述了目前已经商业化生产的锂离子电池负极材料,主要包括天然石墨,人造石墨,硬碳,软碳,Li₄Ti₅O₁₂材料,硅基材料等.详细阐述了这些负极材料的优缺点,并对它们的性能优劣进行了对比,给出了各自具有代表性的充放电曲线.概述了各类负极材料目前的国内外市场状况,并对未来几年锂离子电池负极材料市场的发展趋势进行了预估.介绍了各类负极材料的产业化现状,包括主流生产工艺,产品应用领域,行业领先企业等,总结了各类负极材料,尤其是天然石墨和人造石墨在中国的早期研发历史,并整理了各类负极材料在国内最早发表的文章和专利.最后概述了目前整个锂离子电池负极材料行业存在的一些问题,讨论了目前锂离子电池负极材料的发展思路,并展望了未来的技术发展趋势.     

Preparation and characterization of tin-based three-dimensional cellular anode for lithium ion battery

A three-dimensional cellular Sn-based anode has been prepared by electrodepositing tin onto 3D copper matrix under different current conditions and characterized by means of scanning electron microscope (SEM), X-ray diffraction (XRD), electrochemical cycling test. The properties of tin layer, such as particle size, porosity and shape, greatly affect cycling behavior of electrodes. Beside this, two additional factors including large bonding force and three-dimensional stress-alleviated environment are also important to the dimensional stability of electrodeposited layer. In order to improve cycling performance, a composite anode configuration is designed by casting inactive carbon black into the “valley-ridge” tin-coated architecture. Capacity fading of both anodes is remarkably suppressed with the help of mechanical compression coming from stuffing. Taking advantage of the 3D electrode configuration, CTA with stuffing experiences a more uniform diffusion process to form an intermetallic layer of Cu₆Sn₅ when heated and shows better cyclicity than 2D annealed anode.     

Fabrication of all-solid-state lithium battery with lithium metal anode using Al2O3-added Li7La3Zr2O12 solid electrolyte

Li₇La₃Zr₂O₁₂ (LLZ) solid electrolyte is one of the promising electrolytes for all-solid-state battery due to its high Li ion conductivity and stability against Li metal anode. However, high calcination temperature for LLZ preparation promotes formation of La₂Zr₂O₇ impurity phase. In this paper, an effect of Al₂O₃ addition as sintering additive on LLZ solid electrolyte preparation and electrochemical properties of Al₂O₃-added LLZ were examined. By the Al₂O₃ addition, sintered LLZ pellet could be obtained after 1000 °C calcination, which is 230 °C lower than that without Al₂O₃ addition. Chemical and electrochemical properties of the Al₂O₃-added LLZ, such as stability against Li metal and ion conductivity, were comparable with the LLZ without Al₂O₃ addition, i.e. σ_bulk and σ_total were 2.4 × 10⁻⁴ and 1.4 × 10⁻⁴ S cm⁻¹ at 30 °C, respectively. All-solid-state battery with Li/Al₂O₃-added LLZ/LiCoO₂ configuration was fabricated and its electrochemical properties were tested. In cyclic voltammogram, clear redox peaks were observed, indicating that the all-solid-state battery with Li metal anode was successfully operated. The redox peaks were still observed even after one year storage of the all-solid-state battery in the Ar-filled globe-box. It can be inferred that the Al₂O₃-added LLZ electrolyte would be a promising candidate for all-solid-state battery because of facile preparation by the Al₂O₃ addition, relatively high Li ion conductivity, and good stability against Li metal and LiCoO₂ cathode.     

Interconnected Na2Ti3O7 nanotube/g-C3N4/graphene network as high performance anode materials for sodium storage

The high-performance anode electrode material has been the major challenge of sodium ion batteries (SIBs). In this paper, we report a facile strategy to fabricate three-dimensional (3D) network structures where Na₂Ti₃O₇ nanotube species are anchored to the composites composed of graphite phase carbon nitride (g-C₃N₄) and ultrafine graphene, and demonstrates the excellent electrochemical performance as a sodium storage material. The good integration of g-C₃N₄ and graphene provides more active sites for Na⁺ insertion/extraction and accommodates the volume expansion of Na₂Ti₃O₇. The Na₂Ti₃O₇ nanotube into these carbon matrix can effectively shorten the transport paths of Na⁺. Therefore, the Na₂Ti₃O₇NT/g-C₃N₄/RGO electrode exhibits a superior cycling efficiency and rate capability. When used as the anode material of sodium half-cell, the reversible capacity of the synthesized Na₂Ti₃O₇NT/g-C₃N₄/RGO composite is as high as 210.8 mAh g⁻¹ after 300 cycles at 0.1 A g⁻¹ and good rate capability (104.7 mAh g⁻¹ at 2 A g⁻¹). After the 50 cycle, the corresponding coulomb efficiency remained basically stable and is up to 98%. In addition, the half-cell provides high energy density of 364 Wh kg⁻¹ at power density of 0.048 W kg⁻¹.     

Nanosized tin anode prepared by laser-induced vapor deposition for lithium ion battery

Nanosized tin powder was prepared by laser-induced vapor deposition and studied as an alternative anode material for lithium ion batteries. The nano tin particles are spherical, and their size varies from 5 nm to 80 nm. The prepared powder consists of two compounds: a major amount of Sn and a minor amount of SnO. Results of cyclic voltammograms (CVs) indicate that SnO is deoxidized to Sn almost completely in the first cycle. The reaction of tin with lithium proceeds in two steps. At first, a Li-deficient phase is formed, later a Li-rich phase. Reaction kinetics are controlled by a diffusion step, and the diffusion coefficient of lithium ions in the anode is calculated to be 4.15 × 10⁻⁸ cm² s⁻¹. The initial charge capacity is nearly to the theoretical reversible capacity of lithium insertion into tin, resulting in Li₂₂Sn₅.     

Electrolytic Sn/Li2O coatings for thin-film lithium ion battery anodes

Sn/Li₂O composite coatings on stainless steel substrate, as anodes of thin-film lithium battery are carried out in SnCl₂ and LiNO₃ mixed solutions by using cathodic electrochemical synthesis and subsequently annealed at 200 °C. Through cathodic polarization tests, three major regions are verified: (I) O₂ + 4H⁺ + 4e⁻ → 2H₂O (∼0.25 to −0.5 V), (II) 2H⁺ + 2e⁻ → H₂, Sn²⁺ + 2e⁻ → Sn, and NO₃⁻ + H₂O + 2e⁻ → NO₂⁻ + 2OH⁻ (−0.5 to −1.34 V), and (III) 2H₂O + 2e⁻ → H₂ + 2OH⁻ (−1.34 to −2 V vs. Ag/AgCl). The coated specimens are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and charge/discharge tests. The nano-sized Sn particles embedded in Li₂O matrix are obtained at the lower part of region II such as −1.2 V, while the micro-sized Sn with little Li₂O at the upper part, such as −0.7 V. Charge/discharge cycle tests elucidated that Sn/Li₂O composite film showed better cycle performance than Sn or SnO₂ film, due to the retarding effects of amorphous Li₂O on the further aggregation of Sn particles. On the other hand, the one tested for cut-off voltage at 0.9 V (vs. Li/Li⁺) is better than those at 1.2 and 1.5 V since the incomplete de-alloy at lower cut-off voltage may inhibit the coarsening of Sn particles, revealing capacity 587 mAh g⁻¹ after 50 cycle, and capacity retention ratio C50/C2 81.6%, higher than 63.5% and 49.1% at 1.2 and 1.5 V (vs. Li/Li⁺), respectively.     

Surface structure and electrochemical characteristics of plasma-fluorinated petroleum cokes for lithium ion battery

Plasma-fluorination of petroleum coke and those heat-treated at 1860, 2300 and 2800 °C (abbreviated to PC, PC1860, PC2300 and PC2800) was conducted for 15, 30 and 60 min using CF₄ gas at 90 °C. Fluorine contents obtained by elemental analysis were negligible except PC fluorinated for 60 min (0.7 at.%). Fluorine concentration on the surface decreased with increasing heat-treatment temperature of petroleum coke, i.e. from PC to PC2800 when plasma-fluorination was made for 30 and 60 min. Transmission electron microscopic observation revealed that the closed edges of PC2800 were destroyed and opened by plasma-treatment. Plasma-fluorination increased surface disorder of heat-treated petroleum cokes, however, slightly reduced surface areas. These surface structure changes increased first coulombic efficiencies of PC2300 and PC2800 by 6–8 and 8–10% at both 60 and 150 mA g⁻¹, respectively.     

Research progress of novel binders for silicon-based anode in lithium ion battery

硅基材料由于具有超高的理论比容量,安全的嵌锂工作电位和廉价易得等诸多优点,是下一代高比能量电池体系最理想的负极材料。尽管硅基材料的研究已经进行很长时间,但是硅基材料嵌锂时巨大的体积膨胀,循环性能较差等问题一直难以得到有效解决。开发高性能硅基负极黏结剂是解决硅基材料应用问题的重要途径之一,具有“刚柔并济”结构特性的黏结剂分子能够有效抑制硅基材料结构膨胀粉化,保持电极导电网络的完整性,从而有效提升其循环性能。本文综述了硅基负极黏结剂的特性要求,新型硅基负极黏结剂的研究进展,并对该领域未来潜在的研究方向进行了展望：复合体系聚合物黏结剂的开发;特殊空间构型黏结剂的开发;新型导电黏结剂的开发;自支撑无黏结剂硅基负极的开发。     

Hierarchical novel NiCo2O4/BiVO4 hybrid heterostructure as an advanced anode material for rechargeable lithium ion battery

Hybrid metal oxide heterostructures have been considered as ideal and potential anode materials for lithium ion batteries (LIBs) due to their better electrochemical performances, such as reversible capacity, structural stability and electronic conductivity. Herein, we have demonstrated synthesis of NiCo₂O₄/BiVO₄ heterostructures by simple hydrothermal strategy to construct hybrid xNiCo₂O₄/(1–x)BiVO₄ heterostructures with four selected compositions, that is, x = 10%, 20%, 30% and 40%. XRD shows the phases of NiCo₂O₄ and BiVO₄ and FE-SEM data revealed strong interface coupling between NiCo₂O₄ nanowires and BiVO₄ dendrites. Upon testing for electrochemical properties, the optimized composition of 30%NiCo₂O₄-70% BiVO₄ showed higher reversible capacity of 408.6 mAh/g at a constant current rate of 0.5 A/g after 1000 cycles with columbic efficiency around 99% suggesting potential electrode material for high-performance LIBs. The higher capacity is mainly attributed to the large surface area which can provide more channels and locations for fast Li ion intercalation/de-intercalation into electrode materials. Additionally, improved Li ion storage capacity with superior rate capability of BN-30 electrode could be attributed to its lower charge-transfer resistance. The dendritic and nanowire heterostructure novel system with good stable capacity for LIBs is hitherto unattempted.     

A new process of preparing composite microstructure anode for lithium ion batteries

A composite material anode for lithium ion batteries (LIB) consisted of electrodeposited Sn–Sb alloy dispersing in a conductive micro-porous carbon membrane coated on Cu current collector was investigated. The composite material was obtained by directly electrodepositing Sn–Sb alloy on the micro-porous membrane electrode via micro-pores in it, which was prepared by casting a polyacrylonitrile (PAN) solution containing polyethylene glycol (PEG) on a copper foil and then immersing the copper foil into de-ionized water to perform phase inversion, following by heat-treatment. SEM examinations showed that the composite material consisted of isolated pillar-like structure SnSb electrodeposited on Cu current collector dispersing in a conductive micro-porous carbon membrane deriving from pyrolysis of PAN. Constant current charge and discharge tests using the composite anode showed stable coulombic efficiency and desirable cyclability. The reversible discharging capacity was 339.5 mAh g⁻¹after 50 cycles, corresponding to 78.6% of the discharge capacity retention.     

Recent research progress of Li4Ti5O12 as anode materials for lithium-ion batteries

锂离子电池凭借诸多优势广泛应用于便携式电子产品（3C）领域,在电动汽车及可穿戴设备方面具有巨大应用前景,是未来最具潜力的储能电池之一。作为一种锂离子电池负极材料,尖晶石型Li₄Ti₅O₁₂相比石墨负极具有较高嵌锂电位,且"零应变材料"的特性决定Li₄Ti₅O₁₂材料具有较好的循环稳定性及热稳定性,从而备受关注。本文简要介绍了钛酸锂（Li₄Ti₅O₁₂）的结构和性能,详细阐明了Li₄Ti₅O₁₂的嵌锂机制、制备及改性方法,总结了相应制备及改性方法对Li₄Ti₅O₁₂材料的充放电特性、循环性能等电化学性能的影响,针对Li₄Ti₅O₁₂的胀气产生原因、机制和胀气解决方法进行简单阐述,并对纯电动乘用车的应用前景提出了几点建议。     

Enhancing the electrochemical properties of NiFe2O4 anode for lithium ion battery through a simple hydrogenation modification

Nanocrystal NiFe₂O₄ (NFO) octahedron with a spinel structure has been successfully synthesized by a one-step hydrothermal method. The effects of hydrogenation on the crystal structure, morphology, surface structure, and the electrochemical performance of NFO are comprehensively investigated for the first time. After hydrogenation, the well-defined octahedron morphology of NFO disappears and a small fraction of metallic Ni and some oxygen vacancies are generated after hydrogenation which has been characterized by X-ray diffraction (XRD), X-ray photoelectronic spectrometer (XPS) and Positron annihilation lifetime spectroscopy (PALS). Compared to the pristine NFO or the annealed NFO in air, the hydrogenated samples exhibit much better capacity retention (60% higher than un-hydrogenated NFO at 50th cycle) and rate capability (3 times higher at 1 A/g), which can be largely attributed to the synergetic effect of the conductive metallic Ni and oxygen vacancies resulting from H₂ reduction. Furthermore, this facile hydrogenation modification method may also be applied to improve the electrochemical performances of other transition metal oxides electrodes.     

Facile synthesis and electrochemical properties of Fe3O4 nanoparticles for Li ion battery anode

Nanostructured Fe₃O₄ nanoparticles were prepared by a simple sonication assisted co-precipitation method. Transmission electron microscopy, X-ray diffraction and BET surface area analysis confirmed the formation of ∼20 nm crystallites that constitute ∼200 nm nanoclusters. Galvanostatic charge-discharge cycling of the Fe₃O₄ nanoaprticles in half cell configuration with Li at 100 mA g⁻¹ current density exhibited specific reversible capacity of 1000 mAh g⁻¹. The cells showed stability at high current charge-discharge rates of 4000 mA g⁻¹ and very good capacity retention up to 200 cycles. After multiple high current cycling regimes, the cell always recovered to full reversible capacity of ∼1000 mAh g⁻¹ at 0.1 C rate.     

Porous NiO/poly(3,4-ethylenedioxythiophene) films as anode materials for lithium ion batteries

NiO/poly(3,4-ethylenedioxythiophene) (PEDOT) films are prepared by chemical bath deposition and electrodeposition techniques using nickel foam as the substrate. These composite films are porous, and constructed by many interconnected nanoflakes. As anode materials for lithium ion batteries, the NiO/PEDOT films exhibit weaker polarization and better cycling performance as compared to the bare NiO film. Among these composite films, the NiO/PEDOT film deposited after 2 CV cycles has the best cycling performance, and its specific capacity after 50 cycles at the current density of 2 C is 520 mAh g⁻¹. The improvements of these electrochemical properties are attributed to the PEDOT, a highly conductive polymer, which covers on the surfaces of the NiO nanoflakes, forming a conductive network and thus enhances the electrical conduction of the electrode.     

A novel carbon-silicon composite nanofiber prepared via electrospinning as anode material for high energy-density lithium ion batteries

Electrospun carbon-silicon composite nanofiber is employed as anode material for lithium ion batteries. The morphology of composite nanofiber is optimized on the C/Si ratio to make sure well distribution of silicon particles in carbon matrix. The C/Si (77/23, w/w) nanofiber exhibits large reversible capacity up to 1240 mAh g⁻¹ and excellent capacity retention. Ex situ scanning electron microscopy is also conducted to study the morphology change during discharge/charge cycle, and the result reveals that fibrous morphology can effectively prevent the electrode from mechanical failure due to the large volume expansion during lithium insertion in silicon. AC impedance spectroscopy reveals the possible reason of unsatisfactory rate capability of the nanofiber. These results indicate that this novel C/Si composite nanofiber may has some limitations on high power lithium ion batteries, but it can be a very attractive potential anode material for high energy-density lithium-ion batteries.     

Effect of Cu2O coating on graphite as anode material of lithium ion battery in PC-based electrolyte

Cuprous oxide-coated graphite was synthesized by a polyol reduction process and analyzed by scanning electron microscopy, charge–discharge measurements and cyclic voltammetry. Cu₂O exists at the surface of graphite in the form of nanoparticles and nanorods. The coated cuprous oxide layer acts as a protective layer separating graphite from the propylene carbonate (PC)-based electrolyte solution, and greatly suppresses PC decomposition and graphite exfoliation in PC-based electrolyte systems.