Potential For Lithium-ion Batteries Research Articles

Electrochemically driven amorphization of (Li-)Ti-P-O nanoparticles embedded in porous CNTs for superior lithium storage performance

Amorphous materials have many advantages over their crystalline states in transfering Li+ without restriction of defects, tolerating large volume change during the charging/discharging process and achieving a higher potential in lithium-ion batteries (LIBs). Crystalline LiTi2(PO4)3/TiP2O7 nanoparticles embedded in porous CNTs were constructed firstly by sol-gel and calcination, in which sulfonated polymer nanotubes as both carbon source and template. Afterwards, amorphous (Li-)Ti-P-O nanoparticles embedded in porous CNTs were formed by electrochemical activation. Due to amorphous (Li-)Ti-P-O nanoparticles providing the multi-channel transport of Li+ and the porous carbon matrix preventing the gathering and pulverization of (Li-)Ti-P-O nanoparticles during the electrochemical process, (Li-)Ti-P-O/C hybrid nanotubes exhibit stable cyclic performances and good rate capacities (the capacities of Li-Ti-P-O/C and Ti-P-O/C hybrid nanotubes possess 388.9 and 457.2 mAh g−1 at 0.2 A g−1 after 500 cycles, and maintain 155.0 mAh g−1 at 5 A g−1 after 500 cycles and 123.3 mAh g−1 at 5 A g−1 after 3000 cycles, respectively). This paper provides a feasible method for the preparation of other anode materials with superior lithium storage performance.

Engineering of electrospun polyimide separators for electrical double-layer capacitors and lithium-ion cells

Functionalised polyimide (PI) separators, with high electrolyte wettability and good thermo-dimensional stability, in combination with electrolytes provide ionic conductivities > 1 mS for electrical double-layer capacitors (EDLCs) and lithium-ion batteries (LIBs). The mechanical strength of PI separators can be further improved by a factor of 3 via the optimisation of ratio of soft and hard segments, and the introduction of 5% SiO2 nanoparticles (NPs). The electrolyte uptake capability and ionic conductivity of this copolymerized PI separator is also promoted by the addition of SiO2 NPs, favouring the high-rate performances of EDLCs and LIBs. The cyclic voltammetry (CV) curves of an EDLC with this separator show the rectangle shape of a typical capacitor, indicating the low ionic resistance of this copolymerized PI separator. For the usage in the LIBs, on the other hand, a coating of low-density polyethylene (LDPE) onto this PI-SiO2 (PI–SiO2@PE) separator enables the thermal shutdown function of a LIB without sacrificing cell performance. There is no significant change in morphology for this PI-SiO2@PE separator after the 50-cycle full cell test, indicating its promising application potential in LIBs. The study has demonstrated the ability to tailor the multi functionality of the polyimide separator to optimise it properties for specific applications.

Construction of carbon confined CoP@carbon nanotube hybrid networks assisted by phytic acid toward high-performance lithium-ion batteries

The transition metal phosphides (TMPs) as alternative anode materials have considerable potential for lithium-ion batteries (LIBs) due to their high theoretical capacity. However, the poor-rate capability and capacity degradation arisen from low electrical conductivity and structural change are still great challenging bottlenecks for TMPs-based anodes. Here, we synthesize the carbon-terminated CoP@carbon nanotube (CoP@CNT) composites by the thermal decomposition of phytic acid (PA) cross-linked cobalt complexes intertwined with carbon nanotubes (CNTs). Compared to other phosphorization processes, the PA-assisted approach is more green, safe, and suitable for mass production. More importantly, the PA can also be served as carbon source to direct realization of in-situ carbon-coating during the sintering process. When used the CoP@CNT as an anode for LIBs, the CNT skeleton can provide high-speed pathways for electron/ion transport; meanwhile, the carbon layer physically restricts the CoP to alleviate volume change effectively. Benefiting from these merits, the CoP@CNT electrodes exhibit an average lithium storage capacity of 1159 mA h g−1 at 0.2 A g−1, excellent rate capability (425 mA h g−1 at 10 A g−1), and cyclic stability (524 mA h g−1 after 900 cycles at 2 A g−1).

Inter-layer-calated Thin Li Metal Electrode with Improved Battery Capacity Retention and Dendrite Suppression.

An inter-layer-calated thin Li metal (ILC-Li) electrode using nondelaminated 2D Ti3C2Tx MXene stacks (15 μm) coated on a thin Li host (30 μm) was developed. The excellent electrical conductivity and expanded interlayer space of the MXene provide a fast e-/Li+ transport while the layer limits the Li growth along the perpendicular direction, thus largely mitigating the dendrite growth. The highly reversible Li deposition/extraction greatly reduces the dead lithium and electrolyte consumption by forming a thin solid-electrolyte-interphase (SEI) layer. A small overpotential of less than 135 mV in symmetric cells was achieved after >1050 cycles at 10 mA cm-2 and 10 mAh cm-2. In a full cell, the battery exhibited an improved capacity retention when compared with Li foil, particularly with lean electrolyte of 2.5 μL mAh-1, thus leading to a high energy density up to 366.6 Wh/kg. The current approach is manufacture scalable, which displays promising potentials in lithium ion batteries.

Controllable hydrogel-thermal synthesis of Mn2O3/CNT aerogels: Shape evolution, growth mechanism and electrochemical properties

Manganese oxides (MnOx) have drawn much attention due to their low cost, low toxicity, multiple valence states, excellent electrochemical properties, and have shown great potential for lithium ion batteries, supercapacitors etc. In this work, three-dimensional Mn2O3/CNT aerogels with controllable morphologies including nanocubes, nanorods and nanowires, are synthesized via one-step hydrogel-thermal method. The mechanism for the hydrogel-thermal synthesis has been preliminarily presented. Our experimental results demonstrate that the precursor concentration, the cationic surfactant and confined space of hydrogel play important roles in the nanostructure growth. The electrochemical performances of the Mn2O3/CNT aerogels as free-standing positive material of rechargeable Li-ion batteries have also been researched. It is found that the Mn2O3 nanowires/CNT aerogels show a better rate capability and higher specific capacity of 868 mAh·g−1 at 0.2 A/g. Our research highlights that in situ growth of nanostructured materials in hydrogels may provide another strategy for the 3D porous materials with interesting structures and high performance.

Versatile Utilizations of Cellulose Nanofibers for High-Performance Silicon Anode in Lithium-Ion Batteries

Silicon is the most anticipated anode material in lithium-ion batteries due to its natural abundancy, low insertion voltage (<0.4 V vs. Li/Li+) and high specific capacity (<3579 mAh g-1). However, huge volume change (~ 300 %) during cycling which causes poor cycling stability and its insulating nature prohibit the practical use. In this research, cellulose nanofibers were utilized in various ways to enhance the performance of silicon nanoparticle anodes. As carbon sources, the ultrathin (~ 1.55 nm) cellulose nanofibers can provide an extensive conductive network to improve both the cycling stability and rate performance by mitigating the volume expansion of silicon and providing the efficient electron path. Furthermore, by using thicker (~ 30 nm) cellulose nanofibers as carbon sources, a porous conductive network can be achieved, which can provide both the efficient electron path and ion diffusion path. In addition, the void space generated by cellulose nanofibers became a buffer space which enhanced the cycling stability. Finally, as a binder additive, cellulose nanofiber can enhance the performance of carboxymethyl cellulose binder. It can act as both a filler and a binder to be utilized in an electrode composite, unlike the traditional reinforcing fillers. Therefore, the versatile, cheap and abundant cellulose nanofibers show great potential in lithium-ion batteries.

Multiple phase N-doped TiO2 nanotubes/TiN/graphene nanocomposites for high rate lithium ion batteries at low temperature

It is extremely important to develop anode materials alternative to graphite at low temperature (below 0 °C) from the viewpoint of safety and capacity for lithium ion batteries. TiO2, as a promising anode material, has poor electronic conductivity and ionic conductivity, thus limiting its rate performance at low temperature. Herein, we have designed a novel multiple-phase composites composed of N-doped TiO2/TiN/graphene to improve the ionic conductivity and electronic conductivity and then ameliorate its electrochemical performance at low temperature. The as-prepared nanocomposites show excellent performance as anode in lithium ion batteries at low temperature (0, −10 and −20 °C). Even at −20 °C, the optimized nanocomposites exhibit high reversible specific capacity (211 mAh g−1 at 0.1 A g−1), excellent rate performance (150 mAh g−1 at 1 A g−1) and good cycling stability (∼93% within 500 cycles), indicating superior electrochemical performance at low temperature. Furthermore, the as-prepared nanocomposites are able to deliver ∼154 mAh g−1 at 20 A g−1 at room temperature. Considering the intrinsic safety, excellent electrochemical performance and good adaptability at both low and room temperature, the prepared nanocomposites can have great potential in lithium ion batteries.

Gel polymer electrolyte with high performances based on biodegradable polymer polyvinyl alcohol composite lignocellulose

Abstract A novel gel polymer electrolyte (GPE) is prepared based on polyvinyl alcohol (PVA) composite lignocellulose (LC). In this work, mechanical strength of PVA composite LC membranes is significantly enhanced, which endows corresponding GPEs with application potential in lithium ion batteries (LIBs). Meanwhile, when the content of PVA is 5 wt.%, GPE presents high enough liquid electrolyte uptake (425 wt.%) and enough thermal stability. At room temperature, the ion conductivity is 3.92 × 10−3 S cm−1 and lithium ion transference number is up to 0.63. In addition, GPE exhibits electrochemical stability window at 5.2 V (vs. Li/Li+), good compatibility with electrode, excellent initial discharge specific capacity, C-rate and cycling performances.

TiO2 nanocrystalline-assembled mesoporous nanosphere as high-performance anode for lithium-ion batteries

Through a facile chemical route, TiO2 nanosphere with the size of around 230 nm is assembled by TiO2 nanocrystalline (about 10 nm) and possess abundant mesopores throughout the entire nanosphere, forming TiO2 nanocrystalline-assembled mesoporous nanosphere. The small size of TiO2 nanocrystalline and large specific surface area (153 m2 g−1) of the mesoporous nanosphere significantly boost reaction kinetics of TiO2, and enhance the bulk intercalation and the interfacial storage, which remarkably increases lithium storage capacity of TiO2. Average discharge capacity over 100 cycles at 1 C reaches 219.2 mAh g−1, demonstrating the superiority of this material structure and its potential in lithium ion batteries.

Sol–gel electrospun mesoporous ZnMn2O4 nanofibers with superior specific surface area

ZnMn2O4 has application potential in lithium ion batteries, supercapacitors, sensors, and thermistors. In this study, mesoporous spinel ZnMn2O4 nanofibers were synthesized by sol–gel assisted electrospinning combined with calcination, using poly(styrene-co-acrylonitrile) as sacrificial polymeric binder. Structural, morphological and optical properties of these ceramic nanofibers were characterized. X-ray diffraction and X-ray photoelectron spectroscopy results revealed the presence of hexagonal ZnMnO3 and MnO phases in the ZnMn2O4 nanofibers produced. Based on these observations we propose a plausible mechanism of formation of ZnMn2O4 nanofibers. The nanofibers calcined at 773 K exhibit a specific surface area of 79.5 m2 g−1, which is higher than that of the zinc manganite nanofibers synthesized hitherto by sol–gel electrospinning. Moreover, this material exhibits four bandgaps, which is believed to be the first observation in ZnMn2O4 nanofibers.

Reaction Kinetics and Morphological Study of TiNb2O7 Synthesized by Solid-State Reaction

AbstractAlthough TiNb2O7is regarded as a material with high application potential in lithium-ion batteries (LIBs) and solid-oxide fuel cells (SOFCs), it has been difficult to find suitable cost-effective conditions for synthesizing it on a commercial scale. In this study, TiNb2O7compounds were synthesized by a solid state synthesis process. For stoichiometrically precise synthesis of the TiNb2O7phase, the starting materials, TiO2and Nb2O5were taken in a 1:1 molar ratio. Activation energy and reaction kinetics of the system were investigated at various synthesis temperatures (800,1000,1200, and 1400°C) and for various holding durations (1,5,10, and 20 h). Furthermore, change in the product morphology and particle size distribution were also evaluated as a function of synthesis temperature and duration. Additionally, quantitative phase analysis was conducted using the Rietveld refinement method. It was found that increases in the synthesis temperature and holding time lead to increase in the mean particle size from 1 to 4.5 μm. The reaction rate constant for the synthesis reaction was also calculated.

Silicon–Carbon Core–Shell Hollow Nanotubular Configuration High-Performance Lithium-Ion Anodes

Silicon anode systems, due to their intrinsic high theoretical specific capacity, show tremendous potential in lithium ion batteries (LIBs). Unfortunately, commercial application still remains elusive due to the cycling-related colossal volume expansion issues following Li alloying and dealloying. Herein, core–shell C@Si@C hollow nanotubes with optimal Si thickness (∼60 nm) showing no microstructural damage during lithiation and delithiation processes, have been developed as a stable anode for LIBs with low first-cycle irreversible loss (FIR) of ∼13% and high areal capacity (∼3 mAhcm–2) for the first time. The hollow Si nanotubes (h-SiNTs) have been generated via our previously reported high-throughput and recyclable, sacrificial MgO wire template fabrication approach. Generation of Si films of varying thickness by low-pressure thermal chemical vapor deposition (LPCVD) with subsequent etching yields h-SiNTs. Modification/optimization of the h-SiNT physical characteristics exhibit improved performance in L...

Facile synthesis and Li-ion storage properties of porous Mn-based oxides microspheres

Porous nanosheets assembled Mn-based oxides (Mn2O3, MnCo2O4 and CoMn2O4) microspheres of diameters about 3–6μm and pore size distribution mainly around 10nm have been synthesized by the same facile solvothermal route without any surfactant followed by a calcination process. In virtue of the porous nanosheets constructed microspheres, the Mn-based oxides microspheres Mn2O3 present specific capacities of 650 mAh/g after 100 charge and discharge cycles. Additionally among the three Mn-based oxides the representative specific capacities present an increasing trend as with the increasing percentage of Co element, the plateau of charge and discharge present a lower trend as with the increasing percentage of Mn element which is more suitable as anode materials in high output full batteries. Then the oxides with different components could be applied in different conditions such as the need for high specific capacity or high output lithium-ion batteries. Consequently the easy fabrication of microspheres and excellent electrochemical performances demonstrate Mn-based oxides’ great potential in lithium-ion batteries.

Controlled formation of uniform nanoshells of manganese oxide and their potential in lithium ion batteries.

Uniform nanoshells of manganese oxides have been successfully prepared by controlling their growth kinetics in solution. The prepared manganese oxides show promising electrochemical performance when used as an anode material in lithium ion batteries.

Cover Picture: General Polyethyleneimine‐Mediated Synthesis of Ultrathin Hexagonal Co3O4 Nanosheets with Reactive Facets for Lithium‐Ion Batteries (ChemElectroChem 1/2016)

The Front Cover picture shows the polyethyleneimine-mediated synthesis of ultrathin hexagonal Co3O4 nanosheets with reactive facets and porous architectures. When tested as anode materials, the ultrathin Co3O4 nanosheets demonstrate great potential in lithium-ion batteries, owing to the high specific capacity, excellent cyclability, and rate capability. More information can be found in the Article by Y. Zhang and co-workers on page 55 in Issue 1, 2016 (DOI: 10.1002/celc.201500377).

Facile synthesis of hierarchical mesoporous CuxCo3-xO4 nanosheets array on conductive substrates with high-rate performance for Li-ion batteries

Hierarchical mesoporous CuxCo3-xO4 nanosheets have been directly grown on Ti foil by a facile hydrothermal method and a subsequent annealing treatment. The rich porosity of the sample heated at 600°C (CCO-600) shows excellent electrochemical performance when as anode for Li-ion batteries. It exhibits very high initial discharge capacity of 1300mAhg−1 at 300mAg−1 (1C=1100mAg−1) and achieves reversible charge capacity as high as 335mAhg−1 at the current density of 50C. More importantly, when altering the current density back to 0.1C, the charge capacity could be recovered to 1045mAhg−1.Such high rate capability indicates that this hierarchical mesoporous CuxCo3-xO4 nanosheets material has great potential in lithium ion batteries.

The reduced basis method applied to transport equations of a lithium-ion battery

Purpose – In this paper, the authors aim to show how to apply the reduced basis method to the transport equations of a lithium-ion battery. Design/methodology/approach – The authors consider a coupled system of nonlinear parameterized partial differential equations (P2DEs), which models the concentrations and the potentials in lithium-ion batteries. Findings – The authors develop an efficient reduced basis approach for the fast and robust numerical solution of the P2DE system. Originality/value – By the reduced basis method, the authors get (reduced) solutions with a speed up factor of up to 18 in the presented examples in comparison to the original finite volume solutions.

Effects of volume strain due to Li–Sn compound formation on electrode potential in lithium-ion batteries

Sn and Sn-based compounds have attracted great interest as candidates for anode materials in lithium-ion batteries. Despite the great deal of attention focused on the effects of the volume change of the Sn anode during the lithiation/delithiation process on the cyclic property of the batteries, its influence on the electrode potential is still not well understood. In this study, by constructing a simple Sn–Li battery system, we have investigated the effects of the volume change associated with the formation of Li–Sn compounds on the electrode potential from the viewpoint of the Gibbs free energy and associated elastic-strain energy. Our experimental results show that (i) α-Sn, which is a low-temperature phase and in thermodynamic non-equilibrium at around 298 K (our experimental temperature), is also formed together with usual β-Sn after several cycles of the lithiation and delithiation processes and (ii) when a Sn plate-shape electrode is lithiated, the experimental electrode potential underruns the value expected thermodynamically. These experimental results can be consistently explained by considering the contribution of the elastic-strain energy to the chemical free energy of formation.