复锂电池用聚合物电解质研究进展

市场现行的锂电池电芯内部含有易燃易爆电解液,电解液的存在给锂离子电池在使用上带来了易挥发、泄露甚至燃烧,爆炸等严重的安全隐患。聚合物电解质的引入能显著降低电池的安全隐患,并且可使电池具有薄型化、轻便化和形状可变的优点。本文重点论述了以聚氧化乙烯(PEO)、聚偏氟乙烯(PVDF)、聚甲基丙烯酸甲酯(PMMA)、聚丙烯腈(PAN)等聚合物为基体的全固态聚合物电解质的科研进展,在文末还阐述了全固态电池开发过程中的其他需要提升的方面。

α-MnO_2 nanoneedle-based hollow microspheres coated with Pd nanoparticles as a novel catalyst for rechargeable lithium-air batteries

The hollow α-MnO2 nanoneedle-based microspheres coated with Pd nanoparticles were reported as a novel catalyst for rechargeable lithium-air batteries. The hollow microspheres are composed ofα-MnO2 nanoneedles. Pd nanoparticles are deposited on the hollow microspheres through an aqueous-solution reduction of PdCl2 with NaBH4 at room temperature. The results of TEM, XRD, and EDS show that the Pd nanoparticles are coated on the surface ofα-MnO2 nanoneedles uniformly and the mass fraction of Pd in the Pd-coated α-MnO2 catalyst is about 8.88%. Compared with the counterpart of the hollow α-MnO2 catalyst, the hollow Pd-coated α-MnO2 catalyst improves the energy conversion efficiency and the charge-discharge cycling performance of the air electrode. The initial specific discharge capacity of an air electrode composed of Super P carbon and the as-prepared Pd-coatedα-MnO2 catalyst is 1220 mA＆#183;h/g （based on the total electrode mass） at a current density of 0.1 mA/cm2, and the capacity retention rate is about 47.3% after 13 charge-discharge cycles. The results of charge-discharge cycling tests demonstrate that this novel Pd-coatedα-MnO2 catalyst with a hierarchical core-shell structure is a promising catalyst for the lithium-air battery.

Template synthesis of MnO_2/CNT nanocomposite and its application in rechargeable lithium batteries

Nanostructured MnO2/CNT composite was synthesized by a soft template approach in the presence of Pluronic P123 surfactant. The product was characterized by X-ray diffraction, thermogravimetric and differential thermal analyses, Fourier transformed infrared spectroscopy and high-resolution transmission electron microscopy. The results show that the sample consists of poor crystalline α-MnO2 nanorods with a diameter of about 10 nm and a length of 30-50 nm, which absorb on the carbon nanotubes. The electrochemical properties of the product as cathode material for Li-MnO2 cell are evaluated by galvanostatic charge-discharge and electrochemical impedance spectroscopy （EIS）. Compared with pure MnO2 electrode, the MnO2/CNT composite delivers a much larger initial capacity of 275.3 mA-h/g and better rate and cycling performance.

Vapor-grown carbon fibers enhanced sulfur-multi walled carbon nanotubes composite cathode for lithium/sulfur batteries

Vapor-grown carbon fibers （VGCFs） were introduced as conductive additives for sulfur-multiwalled carbon nanotubes （S-MWCNTs） composite cathode of lithium-sulfur batteries. The performance of S-MWCNTs composite cathodes with carbon black and VGCFs as sole conductive additives was investigated using scanning electron microscopy （SEM）, galvanostatic charge-discharge tests and electrochemical impedance spectroscopy （EIS）. The results show that the S-MWCNTs composite cathode with VGCFs displays a network-like morphology and exhibits higher activity and better cycle durability compared with the composite cathode with carbon black, delivering an initial discharge capacity of 1254 mA＆#183;h/g and a capacity of 716 mA＆#183;h/g after 40 cycles at 335 mA/g. The interconnected VGCFs can provide a stable conductive network, suppress the aggregation of cathode materials and residual lithium sulfide and maintain the porosity of cathode, and therefore the electrochemical performance of S-MWCNTs composite cathode is enhanced.

Silicon/flake graphite/carbon anode materials prepared with different dispersants by spray-drying method for lithium ion batteries

Silicon/flake graphite/carbon （Si/FG/C） composites were synthesized with different dispersants via spray drying and subsequent pyrolysis, and effects of dispersants on the characteristics of the composites were investigated. The structure and properties of the composites were determined by X-ray diffractometry （XRD）, scanning electron microscopy （SEM） and electrochemical measurements. The results show that samples have silicon/flake graphite/amorphous carbon composite structure, good spherical appearances, and better electrochemical performance than pure nano-Si and FG/C composites. Compared with the Si/FG/C composite using washing powder as dispersant, the Si/FG/C composite using sodium dodecyl benzene sulfonate （SDBS） as dispersant has better electrochemical performance with a reversible capacity of 602.68 mA·h/g, and a capacity retention ratio of 91.58 % after 20 cycles.

γ-Ray Irradiation-Derived MnO/rGO Composites for High Performance Lithium Ion Batteries

We report a γ-ray irradiation reduction method to prepare MnO/reduced graphene oxide （rCO） nanocomposite for the anode of lithium ion batteries. γ-Ray irradiation provides a clean way to generate homogeneously dispersed MnO nanoparticles with finely tuned size on rGO surface without the use of surfactant. The MnO/rGO composite enables a fully charge/discharge in 2 min to gain a reversible specific capacity of 546 （mA-h）/g which is 45 higher than the theoretical value of commercial graphite anode.

Hydrothermal synthesis and energy storage performance of ultrafine Ce2Sn2O7 nanocubes

Ultrafine cube-shape Ce2Sn2O7 nanoparticles crystallized in pure pyrochlore phase with a size of about 10 nm have been successfully synthesized by a facile hydrothermal method.Conditional experiments have been conducted to optimize the processing parameters including temperature,pH,reaction duration,precipitator types to obtain phase-pure Ce2Sn2O7.The crystal structure,morphology and sizes and specific surface area have been characterized by X-ray diffractometer(XRD),Raman spectrum,transmission electron microscope(TEM),high resolution transmission electron microscope(HRTEM),and Brunauer-Emmett-Teller(BET).The as-synthesized Ce2Sn2O7 ultrafine nanocubes have been evaluated as electrode materials for pseudo-capacitors and lithium ion batteries.When testing as supercapacitors,a high specific capacitance of 222 F/g at 0.1 A/g and a good cycling stability with a capacitance retention of higher than 86%after 5000 cycle have been achieved.When targeted for anode material for lithium ion batteries,the nanocubes deliver a high specific reversible capacity of more than 900 mA·h/g at 0.05C rate.The rate capability and cycling performance is also very promising as compared with the traditional graphite anode.

Amorphous CoSnO_3@rGO nanocomposite as an efficient cathode catalyst for long-life Li-O_2 batteries

An amorphous CoSnO3@rGO nanocomposite fabricated using a surfactant‐assisted assembly method combined with thermal treatment served as a catalyst for non‐aqueous lithium‐oxygen(Li‐O2)batteries.In contrast to the specific surface area of the bare CoSnO3 nanoboxes(104.3 m2 g–1),the specific surface area of the CoSnO3@rGO nanocomposite increased to approximately 195.8 m2 g–1 and the electronic conductivity also improved.The increased specific surface area provided more space for the deposition of Li2O2,while the improved electronic conductivity accelerated the decomposition of Li2O2.Compared to bare CoSnO3,the overpotential reduced by approximately 20 and 60 mV at current densities of 100 and 500 mA g?1 when CoSnO3@rGO was used as the catalyst.A Li‐O2 battery using a CoSnO3@rGO nanocomposite as the cathode catalyst cycled indicated a superior cyclic stability of approximately 130 cycles at a current density of 200 mA g–1 with a limited capacity of 1000 mAh g–1,which is 25 cycles more than that of the bare amorphous CoSnO3 nanoboxes.

Fast-ionic conductor Li_(2.64)(Sc_(0.9)Ti_(0.1))_(2)(PO_(4))_(3) doped PVDF-HFP hybrid gel-electrolyte for lithium ion batteries

With increasing demand on energy density of lithium-ion battery,wide electrochemical window and safety performance are the crucial request for next generation electrolyte.Gel-electrolyte as a pioneer for electrolyte solidization development aims to solve the safety and electrochemical window problems.However,low ionic conductivity and poor physical performance prohibit its further application.Herein,a fast-ionic conductor(Li_(2.64)(Sc_(0.9)Ti_(0.1))_(2)(PO_(4))_(3))(LSTP)was added into poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)base gel-electrolyte to enhance mechanical properties and ionic conductivity.Evidences reveal that LSTP was able to weaken interforce between polymer chains,which increased the ionic conductibility and decreased interface resistance during the cycling significantly.The obtained LiFePO_(4)/hybrid gel-electrolyte/Li-metal coin cell exhibited excellent rate capacity(145 mA·h/g at 1C,95 mA·h/g at 3C,28℃)which presented a potential that can be comparable with commercialized liquid electrolyte system.

TiO_2/graphene nanocomposites as anode materials for high rate lithium-ion batteries

A simple strategy to prepare a hybrid of nanocomposites of anatase TiO2/graphene nanosheets （GNS） as anode materials for lithium-ion batteries was reported.The morphology and crystal structure were studied by X-ray diffraction （XRD）,field emission scanning electron microscopy （FE-SEM） and transmission electron microscopy （TEM）.The electrochemical performance was evaluated by galvanostatic charge-lischarge tests and alternating current （AC） impedance spectroscopy.The results show that the TiO2/GNS electrode exhibit higher electrochemical performance than that of TiO2 electrode regardless of the rate.Even at 500 mA/g,the capacity of TiO2/GNS is 120.3 mAh/g,which is higher than that of TiO2 61.6 mAh/g.The high performance is attributed to the addition of graphene to improve electrical conductivity and reduce polarization.

Preparation and electrochemical property of Cs0.35V2O5/Cu composite material

Cs0.35V2O5 was successfully synthesized as cathode material for lithium secondary battery by the rheological phase reaction method from Cs2CO3 and NH4VO3. The Cs0.35V2O5/Cu composite material was prepared by the displacement reaction in CuSO4 solution using zinc powder as a reductant. The structure and electrochemical property of the so-prepared powders were characterized by means of XRD （powder X-ray diffraction） and the galvanostatic discharge-charge techniques. The results show that the electrochemical property of Cs0.35V2O5/Cu composite material is significantly improved compared to the bulk Cs0.35V2O5 material. The Cs0.35V2O5/Cu composite material exhibits the first discharge capacity as high as 164.3 mAh.g -1 in the range of 4.2-1.8V at a current rate of 10 mA.g-1 and remains at a stable discharge capacity of about 110 mAh.g-1 within 40 cycles.

Hybrid Silicon-Carbon Nanostructured Composites as Superior Anodes for Lithium Ion Batteries

We have successfully fabricated a hybrid silicon-carbon nanostructured composite with large area （about 25.5 in^2） in a simple fashion using a conventional sputtering system. When used as the anode in lithium ion batteries, the uniformly deposited amorphous silicon （a-Si） works as the active material to store electrical energy, and the pre-coated carbon nanofibers （CNFs） serve as both the electron conducting pathway and a strain/stress relaxation layer for the sputtered a-Si layers during the intercalation process of lithium ions. As a result, the as-fabricated lithium ion batteries, with deposited a-Si thicknesses of 200 nm or 300 nm, not only exhibit a high specific capacity of 〉2000 mA.h/g, but also show a good capacity retention of over 80% and Coulombic efficiency of 〉98% after a large number of charge/discharge experiments. Our approach offers an efficient and scalable method to obtain silicon-carbon nanostructured composites for application in lithium ion batteries.

Unlocking solid-state conversion batteries reinforced by hierarchical microsphere stacked polymer electrolyte

Pursuing all-solid-state lithium metal batteries with dual upgrading of safety and energy density is of great significance. However, searching compatible solid electrolyte and reversible conversion cathode is still a big challenge. The phase transformation at cathode and Li deformation at anode would usually deactivate the electrode-electrolyte interfaces. Herein, we propose an all-solid-state Li-FeF_(3) conversion battery reinforced by hierarchical microsphere stacked polymer electrolyte for the first time. This gC_(3)N_(4) stuffed polyethylene oxide(PEO)-based electrolyte is lightweight due to the absence of metal element doping, and it enables the spatial confinement and dissolution suppression of conversion products at soft cathode-polymer interface, as well as Li dendrite inhibition at filler-reinforced anode-polymer interface. Two-dimensional(2 D)-nanosheet-built porous g-C_(3)N_(4) as three-dimensional(3 D) textured filler can strongly cross-link with PEO matrix and Li TFSI(TFSI: bistrifluoromethanesulfonimide) anion, leading to a more conductive and salt-dissociated interface and therefore improved conductivity(2.5×10^(-4) S/cm at 60℃) and Li+transference number(0.69). The compact stacking of highly regular robust microspheres in polymer electrolyte enables a successful stabilization and smoothening of Li metal with ultra-long plating/striping cycling for at least 10,000 h. The corresponding Li/LiFePO_(4) solid cells can endure an extremely high rate of 12 C. All-solid-state Li/FeF_(3) cells show highly stabilized capacity as high as 300 m Ah/g even after 200 cycles and of 200 m Ah/g at extremely high rate of 5 C, as well as ultra-long cycling for at least 1200 cycles at 1 C. High pseudocapacitance contribution(>55%) and diffusion coefficient(as high as10^(-12) cm^(2)/s) are responsible for this high-rate fluoride conversion. This result provides a promising solution to conversion-type Li metal batteries of high energy and safety beyond Li-S batteries, which are difficult to realize true "all-solid-state" due to the indispensable step of polysulfide solid-liquid conversion.

High-capacity organic electrode material calix[4] quinone/CMK-3 nanocomposite for lithium batteries

Organic lithium-ion batteries（OLIBs） represent a new generation of power storage approach for their environmental benignity and high theoretical specific capacities.However, it has the disadvantage with regard to the dissolution of active materials in organic electrolyte. In this study, we encapsulated high capacity material calix[4]quinone（C4Q） in the nanochannels of ordered mesoporous carbon（OMC）CMK-3 with various mass ratios ranging from 1：3 to 3：1, and then systematically investigated their morphology and electrochemical properties. The nanocomposites characterizations confirmed that C4Q is almost entirely capsulated in the nanosized pores of the CMK-3 while the mass ratio is less than2：1. As cathodes in lithium-ion batteries, the C4Q/CMK-3（1：2） nanocomposite exhibits optimal initial discharge capacity of 427 mA h g^（-1） with 58.7% cycling retention after 100 cycles. Meanwhile, the rate performance is also optimized with a capacity of 170.4 mA h g^（-1） at 1 C. This method paves a new way to apply organic cathodes for lithium-ion batteries.

SnO_2-CuO/graphene nanocomposites for high performance Li-ion battery anodes

The nanocomposites of SnO2-CuO/graphene are synthesized via a two-step method.CuO nanorods are firstly uniformly loaded on the graphene nanosheets,and then SnO2 nanoparticles are coated on CuO nanorods.SnO2-CuO/graphene nanocomposites exhibit high cyclability and capacity as anode of Li-ion battery.After 30 cycles,the capacity can maintain at 584 mAh g-1 at0.1C rate(10 h per half cycle).The high performance can be ascribed to the synergistic effect among SnO2 nanoparticles,CuO nanorods and graphene nanosheets.The results manifest that the nanocomposites of SnO2-CuO/graphene are very suitable for Li-ion battery anodes.

Grafting polysulfides into a functional N-halo compound for high-performance lithium—sulfur battery

Due to its high energy density,lithium-sulfur(Li-S)battery is considered as the most promising candidate for the energy storage systems,but its practical application is hindered by the dissolution of lithium polysulfides in the electrolyte.In this work,N-bromophthalimide(C8H4NO2Br,NBP),an aromatic molecule with carbophilic,sulfiphilic,lithiophilic,and solvophilic nature,is introduced into active graphene(AG)to fabricate the sulfur composite cathode.The carbophilic NBP is anchored readily on the AG surface viaπ−πstacking interaction.During discharging,the dissolved lithium polysulfide anion(LiS−n)is grafted into the sulfiphilic NBP spontaneously via SN2 substitution reaction to form C8H4NO2SnLi,which brings the dissolved LiS−n back to the AG surface in the composite cathode.Moreover,the lithiophilic and solvophilic nature of NBP improve the wettability of the porous composite cathode,and the electrolyte molecule is easily penetrated into the micro-mesopores of AG to facilitate the diffusion of the electrolyte.Thus,NBP,as a multi-functional compound in Li-S battery,can immobilize LiS−n and enhance the diffusion of the electrolyte.The above features of NBP endow the sulfur composite cathode with improved electrochemical performance in the cycling stability.

Sulfur/nickel ferrite composite as cathode with high-volumetric-capacity for lithium-sulfur battery

Low volumetric energy density is a bottleneck for the application of lithium-sulfur (Li-S)battery.The low- density sulfur cooperated with the light-weight carbon sub- strate realizes electrochemical cycle stability,but leads to worse volumetric energy density.Here,nickel ferrite (NiFe2O4)nanofibers as novel substrate for sulfur not only anchor lithium polysulfides to enhance the cycle stability of sulfur cathode,but also contribute to the high volumetric capacity of the S/nickel ferrite composite.Specifically,the S/ nickel ferrite composite presents an initial volumetric capacity of 1,281.7mA h cm^-3-composite at 0.1C rate,1.9times higher than that of S/carbon nanotubes,due to the high tap density of the S/nickel ferrite composite.

A facile grinding approach to embed red phosphorus in N,P-codoped hierarchical porous carbon for superior lithium storage

Despite red phosphorous(P)-based anodes hold great promise for advanced lithium-ion batteries due to their high theoretical capacity, their practical application is hindered by poor electronic conductivity and drastic volume changes during charge-discharge processes. In order to tackle these issues, herein, a facile grinding method was developed to embed sub-micro-and nano-sized red P particles in N,P-codoped hierarchical porous carbon(NPHPC). Such a unique structure enables P@NPHPC long-cyclic stability(1120 mAh g^-1 after 100 cycles at 100 mA g^-1) and superior rate performance(248 mA h g^-1 at 6400 mA g^-1). It is believed that our method holds great potential in scalable synthesis of P@carbon composites for future practical applications.

Microporous bamboo biochar for lithium-sulfur batteries

Being simple, inexpensive, scalable and environmentally friendly, microporous biomass biochars have been attracting enthusiastic attention for application in lithium-sulfur （Li-S） batteries. Herein, porous bamboo biochar is activated via a KOH/annealing process that creates a microporous structure, boosts surface area and enhances electronic conductivity. The treated sample is used to encapsulate sulfur to prepare a microporous bamboo carbon-sulfur （BC-S） nanocomposite for use as the cathode for Li-S batteries for the first time. The BC-S nanocomposite with 50 wt.% sulfur content delivers a high initial capacity of 1,295 mA-h/g at a low discharge rate of 160 mA/g and high capacity retention of 550 mA-h/g after 150 cycles at a high discharge rate of 800 mA/g with excellent coulombic efficiency （995%）. This suggests that the BC-S nanocomposite could be a promising cathode material for Li-S batteries.

A novel lithium-ion battery comprising Li-rich@Cr_2O_5composite cathode and Li_4Ti_5O_(12) anode with controllable coulombic efficiency

Through meticulous design, a Li-lacking Cr2O5 cathode is physically mixed with Li-rich Li（1.2）Ni（0.13）Co（0.13）Mn（0.54）O2（LNCM） cathode to form composite cathodes LNCM@x Cr2O5（x = 0, 0.1, 0.2, 0.3, 0.35, 0.4, mass ratio） in order to make use of the excess lithium produced by the Li-rich component in the first charge-discharge process. The initial coulombic efficiency（ICE） of LNCM half-cell has been significantly increased from75.5%（x = 0） to 108.9%（x = 0.35）. A novel full-cell comprising LNCM@Cr2O5composite cathode and Li4Ti5O（12） anode has been developed. Such electrode accordance, i.e., LNCM@Cr2O5//Li4Ti5O（12）（＂L-cell＂）, shows a particularly high ICE of97.7%. The ＂L-cell＂ can transmit an outstanding reversible capacity up to 250 mA h g-1and has 94% capacity retention during 50 cycles. It also has superior rate capacities as high as122 and 94 mA h g-（-1）at 1.25 and 2.5 A g-（-1）current densities,which are even better in comparison of Li-rich//graphite fullcell（＂G-cell＂）. The high performance of ＂L-cell＂ benefiting from the well-designed coulombic efficiency accordance mechanism displays a great potential for fast charge-discharge applications in future high-energy lithium ion batteries.