Facile fabrication of porous NiO films for lithium-ion batteries with high reversibility and rate capability

We report the high-rate capability and good cyclability of three-dimension nanoporous NiO films as the anodes of lithium-ion batteries. The NiO films are fabricated by immersing foam nickel substrates in an 80 °C aqueous solution containing ammonia and potassium peroxydisulfate, and subsequent heat treatment at 500 °C. At a rate of 1.0 C, the film electrodes maintain a capacity of 560 mAh g⁻¹ as well as capacity retention of 97% after 100 discharge/charge cycles. When the current density is increased to 14C, 42% of the capacity can be retained. Owing to the ease of large-scale fabrication and superior electrochemical performance, these NiO films will be promising anodes for high-energy-density lithium-ion batteries.     

Effect of conducting additives on the properties of composite cathodes for lithium-ion batteries

In an attempt to achieve lithium-ion batteries with high rate capability, the effect of conducting additives with various shapes and contents on the physical and electrochemical performances was evaluated. Although the density of the cathode decreased upon the addition of the additives, the electrical conductivity and electrochemical performance were greatly improved. The composite cathodes with well-dispersed multi-walled carbon nanotubes (MWCNTs) exhibited excellent high rate capabilities and cyclabilities. In the case of cathode with 8 wt.% of MWCNTs (low density—LD), the highest discharge capacity of 136 mAh/g was obtained at 5 C-rate and capacity retention of 97% for 50 cycles was observed at 1 C-rate of discharge. The cathode with a mixture of 2 wt.% of Super P and 4 wt.% of MWCNTs (LD) also exhibits improved cycle performances. The volume changes in the charge and discharge processes were successfully controlled by the bundles distributed between the host particles.     

Fabrication of porous carbon/Si composite nanofibers as high-capacity battery electrodes

Carbon/Si composite nanofibers with porous structures are prepared by electrospinning and subsequent carbonization processes. It is found that these porous composite nanofibers can be used as anode materials for rechargeable lithium-ion batteries (LIBs) without adding any binding or conducting additive. The resultant anodes exhibit good electrochemical performance; for example, a large discharge capacity of 1100 mAh g^?1 at a high current density of 200 mA g^?1.     

SnS2–graphene nanocomposites as anodes of lithium-ion batteries

SnS₂–graphene nanocomposites are synthesized by a hydrothermal method, and their application as anodes of lithium-ion batteries has been investigated. SnS₂ nanosheets are uniformly coating on the surface of graphene. SnS₂–graphene nanocomposites exhibit high cyclability and capacity. The reversible capacity is 766 mAh/g at 0.2C rate and maintains at 570 mAh/g after 30 cycles. Such a high performance can be attributed to high electron and Li-ion conductivity, large surface area, good mechanical flexibility of graphene nanosheets and the synergetic effect between graphene and SnS₂ nanostructures. The present results indicate that SnS₂–graphene nanocomposites have potential applications in lithium-ion battery anodes.     

Fabrication and characterization of P(VDF-HFP)/SBA-15 composite membranes for Li-ion batteries

This study reports on the preparation of a composite polymer electrolyte for secondary lithium-ion battery. Poly(vinylidiene fluoride-hexafluoropropylene) (P(VDF-HFP)) was used as the polymer host, and mesoporous SBA-15 (silica) ceramic fillers used as the solid plasticizer were added into the polymer matrix. The SBA-15 fillers with mesoporous structure and high specific surface can trap more liquid electrolytes to enhance the ionic conductivity. The ionic conductivity of P(VDF-HFP)/SBA-15 composite polymer electrolytes was in the order of 10⁻³ S cm⁻¹ at room temperature. The characteristic properties of the composite polymer membranes were examined by using FTIR spectroscopies, scanning electron microscopy (SEM), and an AC impedance method. For comparison, the LiFePO₄/Li composite batteries with a conventional microporous polyethylene (PE) separator and pure P(VDF-HFP) polymer membrane were also prepared and studied. As a result, the LiFePO₄/Li composite battery comprised the P(VDF-HFP)/10 wt.% m-SBA-15 composite polymer electrolyte, which achieves an optimal discharge capacity of 88 mAh g⁻¹ at 20 C rate with a high coulomb efficiency of 95%. It is demonstrated that the P(VDF-HFP)/m-SBA-15 composite membrane exhibits as a good candidate for application to LiFePO₄ polymer batteries.     

Reticular Sn nanoparticle-dispersed PAN-based carbon nanofibers for anode material in rechargeable lithium-ion batteries

Reticular tin nanoparticle-dispersed carbon (Sn/C) nanofibers were fabricated by stabilization of electrospun SnCl₄/PAN composite fibers and subsequent carbonization at different temperatures. These Sn/C composite nanofibers used as anode materials for rechargeable lithium-ion batteries (LIBs) show that the Sn/C nanofibers at 700 and 850 °C present much higher charge (785.8 and 811 mA h g^?1) and discharge (1211.7 and 993 mA h g^?1) capacities than those at 550 and 1000 °C and the as-received CNFs at 850 °C, corresponding to coulombic efficiencies of 64.9% and 81.7%, respectively. The superior electrochemical properties of the intriguing Sn/C nanofibers indicate a promising application in high performance Li-ion batteries.     

An enhanced poly(vinylidene fluoride) matrix separator with TEOS for good performance lithium-ion batteries

The low crystallinity poly(vinylidene fluoride)/tetraethyl orthosilicate silane (PVDF/TEOS) composite separator with a finger-like pore structure for lithium-ion battery has been successfully prepared by non-solvent-induced phase separation (NIPS) technique. The PVDF/TEOS composite separator shows the excellent wettability and electrolyte retention properties compared with Celgard 2320 separator. AC impedance spectroscopy results indicate that the novel PVDF/TEOS composite separator has ion conductivity of 1.22 mS cm⁻¹ at 25 °C, higher than that of Celgard 2320 separator (0.88 mS cm⁻¹). The lithium-ion transference number of PVDF composite separator added 0.7% TEOS was 0.481, better than that of Celgard 2400 (0.332). What is more, the lithium-ion batteries assembled with PVDF/TEOS composite separator show good cycling performance and rate capability.

     

Physical and electrochemical characterizations of LiFePO4-incorporated Ag nanoparticles

Olivine-type LiFePO₄ composite materials for cathode material of the lithium-ion batteries were synthesized by using a sol-gel method and were coated by a chemical deposition of silver particles. As-obtained LiFePO₄/C-Ag (2.1 wt.%) composites were characterized by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), conductivity measurements, cyclic voltammetry, as well as galvanostatic measurements. The results revealed that the discharge capacity of the LiFePO₄/C-Ag electrode is 136.6 mAh/g, which is 7.6% higher than that of uncoated LiFePO₄/C electrode (126.9 mAh/g). The LiFePO₄/C coated by silver nanoparticles enhances the electrode conductivity and specific capacity at high discharge rates. The improved capacity at high discharge rates may be attributed to increased electrode conductivity and the synergistic effect on electron and Li⁺ transport after silver incorporation.     

A novel method to fabricate lithium-ion polymer batteries based on LiMn<Subscript>2</Subscript>O<Subscript>4</Subscript>/NG electrodes

A novel method to fabricate lithium-ion polymer batteries (LiPBs) has been developed. The LiPBs was fabricated without microporous polyolefin separators, taking spinel lithium manganese oxide (LiMn₂O₄) and natural graphite (NG) as the electrodes. The thicknesses of the cathodes and the anodes are 190 and 110 μm, respectively. The NG anode was coated with a microporous composite polymer film (20 μm thick) which composed of polymer and ultrafine particles. The coating process was effective and simple to be used in practical application, and ensured the composite polymer film to act as a good separator in the LiPB. The LiPBs assembled with the coated NG anodes and pristine LiMn₂O₄ cathodes presented better electrochemical performances than liquid lithium-ion battery counterparts, proving that the microporous composite polymer film can improve the performance of the coated NG anode. In this paper, the spinel LiMn₂O₄/(coated)NG-based LiPBs exhibited high rate capability, compliant temperature reliability, and significantly, excellent cycling performance under the elevated temperature (55°C).     

PbO@C core–shell nanocomposites as an anode material of lithium-ion batteries

In this study, the electrochemical performance of PbO@C core–shell nanocomposites as an anode material of lithium-ion batteries was reported. The PbO@C nanocomposites were prepared via the pyrolysis of lead benzoate precursor. Compared to the reported Pb-based anodes, the PbO@C nanocomposites exhibited higher reversible capacity and longer cycling life. A reversible capacity of 170 mAh g^?1 could be maintained after discharging/charging for 50 cycles, which was at least 1.5 times than the previously reported values. The enhanced electrochemical performance was attributed to the presence of carbon shells that could alleviate the large volume-change of Pb particles during the alloying/dealloying process.     

Synthesis and characterization of core–shell F-doped LiFePO<Subscript>4</Subscript>/C composite for lithium-ion batteries

Core–shell LiFePO₄/C composite was synthesized via a sol–gel method and doped by fluorine to improve its electrochemical performance. Structural characterization shows that F⁻ ions were successfully introduced into the LiFePO₄ matrix. Transmission electron microscopy verifies that F-doped LiFePO₄/C composite was composed of nanosized particles with a ~3 nm thick carbon shell coating on the surface. As a cathode material for lithium-ion batteries, the F-doped LiFePO₄/C nanocomposite delivers a discharge capacity of 162 mAh/g at 0.1 C rate. Moreover, the material also shows good high-rate capability, with discharge capacities reaching 113 and 78 mAh/g at 10 and 40 C current rates, respectively. When cycled at 20 C, the cell retains 86% of its initial discharge capacity after 400 cycles, demonstrating excellent high-rate cycling performance.     

Platelike CoO/carbon nanofiber composite electrode with improved electrochemical performance for lithium ion batteries

Platelike CoO/carbon nanofiber (CNF) composite materials with porous structures are synthesized from the thermal decomposition and recrystallization of β-Co(OH)₂/CNF precursor without the need for a template or structure-directing agent. As negative electrode materials for lithium-ion batteries, the platelike CoO/CNF composite delivers a high reversible capacity of 700 mAh g⁻¹ for a life extending over hundreds of cycles at a constant current density of 200 mA g⁻¹. More importantly, the composite electrode shows significantly improved rate capability and electrochemical reversibility. Even at a current of 2 C, the platelike CoO/CNF composite maintain a capacity of 580 mAh g⁻¹ after 50 discharge/charge cycles. The improved cycling stability and rate capability of the CoO/CNF composite electrodes may be attributed to synergistic effect of the porous structural stability and improved conductivity through CNF connection.     

Tin oxide–based anodes for both lithium-ion and sodium-ion batteries

Tin oxide, SnO₂, is a suitable anode for both lithium-ion and sodium-ion batteries (LIBs and SIBs) unlike graphite and silicon, which are only suitable anodes for LIB. SnO₂ has garnered much attention because of its high theoretical capacities (LIB = 1494 mA h g^?1 and SIB = 1378 mA h g^?1). However, the commercialization of SnO₂ anodes is still hugely challenged because these anodes suffer from large volume expansion caused by lithiation/delithiation or sodiation/desodiation during cycling, leading to severe capacity fading. The adopted strategies to solve these problems are nanosizing that greatly improves the structural stability of the material and helps to have fast reaction kinetics. Synthesizing nanocomposite of SnO₂ nanoparticles with nanoporous carbonaceous materials to buffer the volume expansion, enhance cycling stability; create oxygen deficiency to improve intrinsic conductivity. In this review, the recent research trends on SnO₂ as anode for both LIB and SIB systems are presented.     

Preparation and characterization of high-rate and long-cycle LiFePO4/C nanocomposite as cathode material for lithium-ion battery

Olivine LiFePO₄/C nanocomposite cathode materials with small-sized particles and a unique electrochemical performance were successfully prepared by a simple solid-state reaction using oxalic acid and citric acid as the chelating reagent and carbon source. The structure and electrochemical properties of the samples were investigated. The results show that LiFePO₄/C nanocomposite with oxalic acid (oxalic acid: Fe²⁺= 0.75:1) and a small quantity of citric acid are single phase and deliver initial discharge capacity of 122.1 mAh/g at 1 C with little capacity loss up to 500 cycles at room temperature. The rate capability and cyclability are also outstanding at elevated temperature. When charged/discharged at 60 °C, this materials present excellent initial discharge capacity of 148.8 mAh/g at 1 C, 128.6 mAh/g at 5 C, and 115.0 mAh/g at 10 C, respectively. The extraordinarily high performance of LiFePO₄/C cathode materials can be exploited suitably for practical lithium-ion batteries.     

Influence of Calcination on the Properties of Nickel Oxide-Samarium Doped Ceria Carbonate (NiO-SDCC) Composite Anodes

Apart from its composition, the starting powder properties such as particle size potentially affect the triple phase boundary and the electrochemical performance. Calcination process has been identified as one of the factors that influence the particle size of the composite anode powders. This study investigates the correlation between calcination temperature and properties (i.e., chemical, physical, and thermal) of NiO–samarium-doped ceria carbonate (SDCC) composite anodes. NiO–SDCC composite anode powder was prepared with NiO and SDCC through high-energy ball milling. The resultant composite powder was subjected to calcination at various temperatures ranging from 600 °C to 800 °C. Characterizations of the composite anode were performed through X-ray diffraction (XRD), Fourier transform infrared spectroscopy, energy dispersive spectroscopy, field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), dilatometry, and porosity measurements. The composite anodes exhibited good chemical compatibility during XRD after calcination and sintering. The FTIR result verified the existence of carbonates in all the composite anodes. The increment in calcination temperature from 600 °C to 800 °C resulted in the growth of nanoscale particles, as evidenced by the FESEM micrographs and crystallite size. Nonetheless, the porosity obtained remained within the acceptable range for a good anodic reaction (20% to 40%). The TGA results showed gradual mass loss in the range of 400 °C to 600 °C (within the low-temperature solid oxide fuel cell region). The composite anodes calcined at 600 °C and 700 °C revealed a good thermal expansion coefficient that matches that of the SDCC electrolyte.     

Importing Tin Nanoparticles into Biomass-Derived Silicon Oxycarbides with High-Rate Cycling Capability Based on Supercritical Fluid Technology

Silicon oxycarbides (SiOC) are regarded as potential anode materials for lithium-ion batteries, although inferior cycling stability and rate performance greatly limit their practical applications. Herein, amorphous SiOC is synthesized from Chlorella by means of a biotemplate method based on supercritical fluid technology. On this basis, tin particles with sizes of several nanometers are introduced into the SiOC matrix through the biosorption feature of Chlorella. As lithium-ion battery anodes, SiOC and Sn@SiOC can deliver reversible capacities of 440 and 502 mAh g⁻¹ after 300 cycles at 100 mA g⁻¹ with great cycling stability. Furthermore, as-synthesized Sn@SiOC presents an excellent high-rate cycling capability, which exhibits a reversible capacity of 209 mAh g⁻¹ after 800 cycles at 5000 mA g⁻¹; this is 1.6 times higher than that of SiOC. Such a novel approach has significance for the preparation of high-performance SiOC-based anodes.     

Frontispiece: Stainless Steel-Like Passivation Inspires Persistent Silicon Anodes for Lithium-Ion Batteries

Passivation of stainless steel by additives forming mass-transport blocking layers is widely practiced, where Cr element is added into bulk Fe−C forming the Cr₂O₃-rich protective layer. Here we extend the long-practiced passivation concept to Si anodes for lithium-ion batteries, incorporating the passivator of LiF/Li₂CO₃ into bulk Si. The passivation mechanism is studied by various ex situ characterizations, redox peak contour maps, thickness evolution tests, and finite element simulations. The results demonstrate that the passivation can enhance the (de)lithiation of Li-Si alloys, induce the formation of F-rich solid electrolyte interphase, stabilize the Si/LiF/Li₂CO₃ composite, and mitigate the volume change of Si anodes upon cycling. The 3D passivated Si anode can fully retain a high capacity of 3701 mAh g⁻¹ after 1500 cycles and tolerate high rates up to 50C. This work provides insight into how to construct durable Si anodes through effective passivation.     

Study of tin dioxide–sodium stannate composite obtained by decomposition of peroxostannate as a potential anode material for lithium-ion batteries

A tin dioxide–sodium stannate composite has been obtained by the thermal treatment of sodium peroxostannate nanoparticles at 500°C in air. X-ray powder diffraction study has revealed that the composite includes crystalline phases of cassiterite SnO₂, sodium stannate Na₂Sn₂O₅, and sodium hexahydroxostannate Na₂Sn(OH)₆. Scanning electron microscopy has shown that material morphology does not change considerably as compared with the initial tin peroxo compound. Electrochemical characteristics have been compared for the anodes of lithium-ion batteries based on tin dioxide–sodium stannate composite and anodes based on a material manufactured by the thermal treatment of graphene oxide–tin dioxide–sodium stannate composite at 500°C in air.     

Magnesium ion-conducting gel polymer electrolytes dispersed with fumed silica for rechargeable magnesium battery application

Effect of fumed silica dispersion on poly(vinylidene fluoride-co-hexafluoropropylene)-based magnesium ion-conducting gel polymer electrolyte has been studied using various physical and electrochemical techniques. The composite gel electrolytes are free-standing and flexible films with enough mechanical strength. The optimized composition with 3 wt.% filler offers a maximum ionic conductivity of ∼1.1 × 10⁻² S cm⁻¹ at ∼25 °C with good thermal and electrochemical stabilities. The Mg²⁺ ion conduction in the gel nanocomposite film is confirmed from the cyclic voltammetry, impedance spectroscopy, and transport number measurements. The space-charge layers formed between filler particles and gel electrolyte are responsible for the enhancement in ionic conductivity. The applicability of the gel nanocomposite to a rechargeable battery is examined by fabricating a prototype cell consisting of Mg [or Mg-multiwalled carbon nanotube (MWCNT) composite] and MoO₃ as negative and positive electrodes, respectively. The discharge capacity and the rechargeability of the cell have been improved when Mg metal is substituted by Mg-MWCNT composite. The discharge capacity of the optimized cell has found to be ∼175 mAh g⁻¹ of MoO₃ for an initial ten charge–discharge cycles.     

PEO-LITFSI-SiO2-SN System Promotes the Application of Polymer Electrolytes in All-Solid-State Lithium-ion Batteries

All-solid-state polymer lithium-ion batteries are ideal choice for the next generation of rechargeable lithium-ion batteries due to their high energy, safety and flexibility. Among all polymer electrolytes, PEO-based polymer electrolytes have attracted extensive attention because they can dissolve various lithium salts. However, the ionic conductivity of pure PEO-based polymer electrolytes is limited due to high crystallinity and poor segment motion. An inorganic filler SiO₂ nanospheres and a plasticizer Succinonitrile (SN) are introduced into the PEO matrix to improve the crystallization of PEO, promote the formation of amorphous region, and thus improve the movement of PEO chain segment. Herein, a PEO₁₈−LiTFSI−5 %SiO₂−5 %SN composite solid polymer electrolyte (CSPE) was prepared by solution-casting. The high ionic conductivity of the electrolyte was demonstrated at 60 °C up to 3.3×10⁻⁴ S cm⁻¹. Meanwhile, the electrochemical performance of LiFePO₄/CSPE/Li all-solid-state battery was tested, with discharge capacity of 157.5 mAh g⁻¹ at 0.5 C, and capacity retention rate of 99 % after 100 cycles at 60 °C. This system provides a feasible strategy for the development of efficient all-solid-state lithium-ion batteries.