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.     

Nickel foam supported Sn-Co alloy film as anode for lithium ion batteries

Sn-Co alloy films are deposited electrochemically directly onto nickel foam in an aqueous solution. The influence of electrochemical current density and heat treatment on the structure and morphology of the electrodeposited films is studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical properties of the Sn-Co alloy films are further investigated by galvanostatic charge-discharge tests. As anodes for lithium ion batteries, the Sn-Co alloy-film anodes, after further heat treatment at 200 °C for 30 min, delivers a specific capacity of 663 mAh g⁻¹ after 60 cycles. This high capacity retention is attributed to the unique electrode configuration with an enhanced interface strength between the active material and the current collector formed in the heat-treatment process.     

Nanosized silicon-based composite derived by in situ mechanochemical reduction for lithium ion batteries

Composite consisting of nanosized silicon, Li₄SiO₄ and other lithium-rich components was synthesized using high energy mechanical milling (HEMM) method. The reactive milling of SiO with lithium metal resulted in the oxidation of lithium and silicon, and reduction of SiO. X-ray diffraction (XRD) and high-resolution transmission electron microscope (HRTEM) were used to determine the phases present in the composite. In addition, cyclic voltammetry (CV), along with constant current discharge/charge tests, was used to characterize the electrochemical properties of the resultant material. Compared with pure SiO and pure silicon as anode materials, the as-prepared composite demonstrated larger capacity and superior cyclability even at high C-rate.     

Carbon-coated SiO2 nanoparticles as anode material for lithium ion batteries

A simple approach is proposed to prepare C-SiO₂ composites as anode materials for lithium ion batteries. In this novel approach, nano-sized silica is soaked in sucrose solution and then heat treated at 900 °C under nitrogen atmosphere. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis shows that SiO₂ is embedded in amorphous carbon matrix. The electrochemical test results indicate that the electrochemical performance of the C-SiO₂ composites relates to the SiO₂ content of the composite. The C-SiO₂ composite with 50.1% SiO₂ shows the best reversible lithium storage performance. It delivers an initial discharge capacity of 536 mAh g⁻¹ and good cyclability with the capacity of above 500 mAh g⁻¹ at 50th cycle. Electrochemical impedance spectra (EIS) indicates that the carbon layer coated on SiO₂ particles can diminish interfacial impedance, which leads to its good electrochemical performance.     

Morphology effect on the electrochemical performance of NiO films as anodes for lithium ion batteries

NiO films were prepared by chemical bath deposition and electrodeposition method, respectively, using nickel foam as the substrate. The films were characterized by scanning electron microscopy (SEM) and the images showed that their morphologies were distinct. The NiO film prepared by chemical bath deposition was highly porous, while the film prepared by electrodeposition was dense, and both of their thickness was about 1 μm. As anode materials for lithium ion batteries, the porous NiO film prepared by chemical bath deposition exhibited higher coulombic efficiency and weaker polarization and its specific capacity after 50 cycles was 490 mAh g⁻¹ at the discharge–charge current density of 0.5 A g⁻¹, and 350 mAh g⁻¹ at 1.5 A g⁻¹, higher than the electrodeposited film (230 mAh g⁻¹ at 0.5 A g⁻¹, and 170 mAh g⁻¹ at 1.5 A g⁻¹). The better electrochemical performances of the film prepared by chemical bath deposition are attributed to its highly porous morphology, which shorted diffusion length of lithium ions, and relaxed the volume change caused by the reaction between NiO and Li⁺.     

Enhanced electrochemical performance of porous NiO-Ni nanocomposite anode for lithium ion batteries

The nickel foam-supported porous NiO-Ni nanocomposite synthesized by electrostatic spray deposition (ESD) technique was investigated as anodes for lithium ion batteries. This anode was demonstrated to exhibit improved cycle performance as well as good rate capability. Ni particles in the composites provide a highly conductive medium for electron transfer during the conversion reaction of NiO with Li⁺ and facilitate a more complete decomposition of Li₂O during charge with increased reversibility of conversion reaction. Moreover, the obtained porous structure is benefical to buffering the volume expansion/constriction during the cycling.     

New strategy to prepare nitrogen self-doped graphene nanosheets by magnesiothermic reduction and its application in lithium ion batteries

Nitrogen self-doped graphene (N/G) nanosheets were prepared through magnesiothermic reduction of melamine. The obtained N/G features porous structure consisting of multi-layer nanosheets. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectra and X-ray diffraction (XRD). As anode of lithium ion batteries (LIBs), it exhibits excellent reversible specific capacity of 1753 mAh g⁻¹ at 0.1 A g^-1 after 200 cycles. The reversible capacity can maintain at 1322 mAh g⁻¹ after 500 cycles at 2 A g⁻¹. At the same time, all results indicate remarkable cycle stability and rate performance as anode materials. Furthermore, this study demonstrates an economical, clean and facile strategy to synthesize N/G nanosheets from cheap chemicals with excellent electrochemical performance in LIBs.     

Carbon-coated graphite for anode of lithium ion rechargeable batteries: Graphite substrates for carbon coating

Anode performance in lithium ion rechargeable batteries (LIBs) was studied on four kinds of graphite powders, including synthetic graphite. Carbon-coated synthetic graphite gave a smaller irreversible capacity of about 20 mAh g⁻¹ and a better cyclic performance in an electrolyte solution of EC/DMC than natural graphite, though its discharge capacity of about 300 mAh g⁻¹ is a little smaller than natural graphite. Even in a PC-containing solution as EC/PC = 3/1, carbon-coated synthetic graphite had almost the same anode performance as in the solution without PC. Carbon coating of above 5 mass% on graphite particles was found to be effective to improve the anode performance at a low temperature of −5 °C, high retention in discharge capacity of about 90% being obtained. On both natural and synthetic graphite powders, carbon coating by the amount of 3–10 mass% at a temperature of 700–1000 °C was found to be optimum for the improvement of anode performance in LIBs, to have a lower irreversible capacity and higher retention in discharge capacity at −5 °C than without carbon coating.     

Carbon-coated graphite for anode of lithium ion rechargeable batteries: Carbon coating conditions and precursors

Carbon coating of natural graphite particles was performed by mechanical mixing of natural graphite with different carbon precursors in a scale of about 100 g. Anode performance in lithium ion rechargeable batteries was studied on the resultant carbon-coated graphite. Carbon formed on graphite particles had amorphous structure and low density. By carbon coating, a decrease in irreversible capacity of the first charge/discharge cycle in an electrolyte solution of EC/PC = 3/1 was observed, without noticeable change in discharge capacity. Carbon derived from different precursors did not give any marked difference in anode performance of carbon-coated graphite. Optimum conditions for carbon coating were determined as the coating of 4-13 mass% at 700-1000 °C. The present mechanical mixing of natural graphite and carbon precursor in powder is concluded to be a simple but sufficient process to produce carbon-coated graphite for anode material in lithium ion rechargeable batteries. As carbon precursor, PVA was shown to be one of the appreciable carbon precursors.     

Recent developments in cathode materials for lithium ion batteries

One of the challenges for improving the performance of lithium ion batteries to meet increasingly demanding requirements for energy storage is the development of suitable cathode materials. Cathode materials must be able to accept and release lithium ions repeatedly (for recharging) and quickly (for high current). Transition metal oxides based on the α-NaFeO₂, spinel and olivine structures have shown promise, but improvements are needed to reduce cost and extend effective lifetime. In this paper, recent developments in cathode materials for lithium ion batteries are reviewed. This includes comparison of the performance characteristics of the promising cathode materials and approaches for improving their performances.     

Silicon-oxycarbide based thin film anodes for lithium ion batteries

We show that anodes made by depositing thin films of polymer-derived silicon oxycarbide (SiCO) on copper have properties that are comparable to, or better than that of powder-based SiCO anodes. The great advantage of the thin film architecture is its simplicity, both in manufacturing and in application. The films are produced by spraying a film of the liquid polymer-precursor on copper, and then converting it into SiCO by heating at ∼1000 °C; at this point they are ready for constructing electrochemical cells. They show a capacity of ∼1000 mA h g⁻¹, 100% coulombic efficiency, good capacity at very high C-rates, and minimal fading at ∼60 cycles. However, if the films are thick they delaminate due to the volume change as lithium is cycled in and out. The transition from thin-film to thick-film behavior occurs when the SiCO films are approximately 1 μm thick. An analytical method for estimating this transition is presented.     

Calculation on energy densities of lithium ion batteries and metallic lithium ion batteries

锂电池是理论能量密度最高的化学储能体系,估算各类锂电池电芯和单体能达到的能量密度,对于确定锂电池的发展方向和研发目标具有重要的参考价值。本工作根据主要正负极材料的比容量、电压,同时考虑非活性物质集流体、导电添加剂、黏结剂、隔膜、电解液、封装材料占比,计算了不同材料体系组成的锂离子电池和采用金属锂负极、嵌入类化合物正极的金属锂离子电池电芯的预期能量密度,并计算了18650型小型圆柱电池单体的能量密度,为电池发展路线的选择和能量密度所能达到的数值提供参考依据。同时指出,电池能量密度只是电池应用考虑的一个重要指标,面向实际应用,需要兼顾其它技术指标的实现。     

Electrodeposited Ni–Sn intermetallic electrodes for advanced lithium ion batteries

Various samples of Ni_xSn_y metallic alloys electrodeposited under different current and time regimes have been prepared and tested in lithium cells. The results clearly demonstrate that the electrochemical performance of these intermetallic electrodes greatly depends on the synthesis conditions which in turn reflect on the type of morphology and phase of the various samples. The best electrode cycled with a high capacity delivery, i.e. of the order of 550 mA hg⁻¹ and showed an efficient behaviour when used as anode in a lithium ion battery using LiNi_0.5Mn_1.5O₄ as cathode. These results confirm that the electrodeposition is a very promising synthesis tool for monitoring the morphological and phase conditions of Ni_xSn_y and that the approach described in this work may be used for further optimizing this intermetallic electrode.     

Preparation and application of bamboo-like carbon nanotubes in lithium ion batteries

CNTs with bamboo-like structure (B-CNTs) has been prepared via a CVD process with novel carbon precursor. The potential application of B-CNTs as electric conductive additive and anode materials for lithium ion batteries was explored. The EIS spectra prove that it is better electric conductive additive than multiwalled CNTs and traditional carbon black (CB). The electric resistance of the electrode is decreased around 20 Ω when B-CNTs is used instead of CB. The cycle stability is also enhanced. However, the test cell with B-CNTs as anode material shows low reversible capacity of 135 mAh g⁻¹ and very low initial cycle efficiency of 17.3%, which indicates that so-prepared B-CNTs is not suitable for anode material.     

All solid state lithium ion rechargeable batteries using NASICON structured electrolyte

Abstract

NASICON (Sodium super ionic conductor) structured Li_1·5Al_0·5Ge_1·5(PO₄)₃ (LAGP) solid electrolyte is synthesized through a solid state reaction. The total conductivity of the LAGP electrolyte is 7×10^?5 S cm^?1 with a potential window larger than 6 V. All solid state lithium batteries are fabricated using LiMn₂O₄ as a cathode, LAGP as an electrolyte and lithium metal as an anode. The LiMn₂O₄/LAGP/Li cell can deliver a capacity of about 80 mAh g^?1 in the first discharge cycle and increases gradually with charge/discharge cycles, indicating that LAGP can be used as a promising electrolyte for lithium rechargeable batteries.     

Surface modified Ni foam as current collector for syngas solid oxide fuel cells with perovskite anode catalyst

Cu surface modified nickel foam is obtained by heating copper coated nickel foam in a reducing atmosphere. La_0.75Sr_0.25Cr_0.5Mn_0.5O_3−δ (LSCM) perovskite oxide is prepared using a sol–gel combustion method. The modified foams and LSCM powders exhibit excellent resistance to carbon deposition in syngas at high temperatures. Furthermore, Cu modified foams show better mechanical strength compared to bare Ni foam, which readily cracks after exposure to syngas at high temperature. LSCM retains its perovskite structure during exposure to syngas or carbon monoxide at 900 °C for 10 h. Cu surface modified Ni foam current collector demonstrates good chemical compatibility with LSCM in syngas atmosphere at high temperature. Syngas solid oxide fuel cells (SOFCs) are assembled using Cu modified Ni foam anode current collector, LSCM anode catalyst, YSZ electrolyte, and porous Pt cathode. The present fuel cell provides similar power density to one with gold anode current collector and has excellent stability during operation at 900 °C.     

Flower-like architecture of CoSn4 nano structure as anode in lithium ion batteries

CoSn₄ nano-particles were synthesized on Cu and Ni substrates through pulsed current electrodeposition and used as anode in lithium ion batteries. Nano particles with Flower-like morphology were obtained through applying an average current density of 85 mA/cm² on Ni substrate while the particles formed using constant current electrodeposition are greater in size ca. 500 nm. Optimum discharge capacity of synthesized CoSn₄ was obtained 848 mAh g^?1 which reduced to 500 mAh g^?1 at 120th cycle indicating an enhanced electrochemical performance compared to anode films synthesized through other pulsed current densities and also constant current electrodeposition. This high discharge capacity and cycleability is attributed to finer crystal grains and flower-like morphology of nano particles. Also, the sample synthesized on Ni substrate showed higher cycleability and noticeably lower resistance. High resistance of anode film synthesized on Cu substrate is due to the corrosion and passivation of copper occurred by HF formation in LiPF₆ electrolyte.     

Overcharge protection effect and reaction mechanism of cyclohexylbenzene for lithium ion batteries

We studied the relationship between the structure of aromatic compounds and the overcharge protection effect, using cyclohexylbenzene, isopropylbenzene, and toluene as the overcharge protection agents. Cyclohexylbenzene proved to be the most effective overcharge protection agent among these aromatic compounds. The effect is enhanced using a higher concentration of cyclohexylbenzene and elevated temperatures. The reaction product of cyclohexylbenzene was analyzed using field desorption mass spectrometry to elucidate its reaction mechanism. The results suggested that some of the overcharge reaction products of CHB were more reactive than that of IPB, which is consistent with the better suppressing effect on overcharging of the active material in the positive electrode.     

High performance silicon carbon composite anode materials for lithium ion batteries

Silicon and silicon containing compounds are attractive anode materials for lithium batteries because of their low electrochemical potential vs. lithium and high theoretical capacities. In this work the relationship between the electrochemical performance of silicon powders and their particle sizes was studied. It is found that the material with nano particle sizes gives the best performance. New silicon/carbon composite anode materials were synthesized and their structures and electrochemical performance were investigated. The results of these studies are reported in this paper.     

Electrochemical properties of carbon-coated Si/B composite anode for lithium ion batteries

Carbon-coated Si and Si/B composite powders prepared by hydrocarbon gas (argon + 10 mol% propylene) pyrolysis were investigated as the anodes for lithium-ion batteries. Carbon-coated silicon anode demonstrated the first discharge and charge capacity as 1568 mAh g⁻¹ and 1242 mAh g⁻¹, respectively, with good capacity retention for 10 cycles. The capacity fading rate of carbon-coated Si/B composite anode decreased as the amounts of boron increased. In addition, the cycle life of carbon-coated Si/B/graphite composite anode has been significantly improved by using sodium carboxymethyl cellulose (NaCMC) and styrene butadiene rubber (SBR)/NaCMC mixture binders compared to the poly(vinylidene fluoride, PVdF) binder. A reversible capacity of about 550 mAh g⁻¹ has been achieved at 0.05 mAm g⁻¹ rate and its capacity could be maintained up to 450 mAh g⁻¹ at high rate of 0.2 mAm g⁻¹ even after 30 cycles. The improvement of the cycling performance is attributed to the lower interfacial resistance due to good electric contact between silicon particles and copper substrate.