电解液中添加剂对锂电池性能的影响研究

锂离子电池的性能和实用价值在全球范围内得到了大家的验证和肯定,它的出色表现离不开电解液的支持。新的探索研究了在电解液里加入多样化的添加剂,探讨它们对锂离子电池的多个性能-电导率,电化学稳定性,和使用寿命周期的改观程度。结果发现添加剂的存在是能提高电解液电导率的,同样能让电解液更稳定,特别是在快速充放和高温环境里的稳定程度更为明显。为更好的为使用者服务,添加剂还能使电池寿命周期增长,大大提高其稳定性和保持其容量。此论文通过电化学分析,阐释了添加剂能带来如此多改变的原因,提供了一种全新的思路来提升锂离子电池的性能。

锌杂质对铅酸蓄电池性能的影响——基于柠檬酸/柠檬酸钠体系回收废铅膏

废铅酸蓄电池在回收过程中会引入大量的锌杂质。本实验采用柠檬酸/柠檬酸钠湿法浸出模拟铅膏,铅膏中锌掺量为1%、0.5%、0.1%、0.05%和0.01%。经浸出、过滤、焙烧后得到铅酸电池活性物质铅粉,将铅粉制备电池,考察其20小时率、1小时率放电和电池循环性能,发现铅膏中锌含量为0.1%时电池的性能最好。

聚电解质-TiO2改性PVDF多孔膜及其电化学性能

采用聚电解质改性的TiO2纳米粒子与聚电解质复合对聚偏氟乙烯(PVDF)多孔膜进行杂化改性,制备了PVDF/聚电解质-TiO2杂化复合膜,考察了改性前后复合膜的界面阻抗与离子电导率变化及其作为锂离子电池隔膜的充放电性能.结果表明,聚二烯丙基二甲基氯化铵(PDDA)与TiO2纳米粒子杂化改性的PVDF复合隔膜的电化学性能优于PVDF原膜,其界面阻抗由原膜的114.5Ω下降至96.9Ω,离子电导率由原膜的1.61×10^-4 S/cm升高至3.12×10^-4 S/cm,且采用该复合隔膜组装的锂离子电池在0.2 C倍率下充放电循环100圈后,放电比容量保持率为75.5%.

三元正极材料清洗废水资源化回收零排放处理工艺

锂电三元正极材料在清洗过程中产生含有Li^(+)、Al^(3+)、SO_(4)^(2-)、镍钴锰氧化物及少量其他离子的废水,对该三元正极材料清洗废水的资源化回收零排放处理工艺进行了阐述。该废水处理系统涉及的成套工艺包括预处理单元、废水减量化单元、沉锂单元和制纯水单元。重点对Al^(3+)的去除、膜浓缩、沉锂等关键工艺进行了重点描述,最后通过实际与理论对比分析,达到了预期的设计目标——锂资源得到有效回收、废水实现全部回用。通过对实际案例的相关数据的例举和分析,证明了本套废水处理工艺的可行性和可靠性,为锂电三元正极材料清洗废水的治理提供了典型的参考工艺路线。

Effect of sintering temperature on cycling performance and rate performance of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_2

LiNi0.8Co0.1Mn0.1O2 powder was prepared by mixing LiOH·H2O and co-precipitated Ni0.8Co0.1Mn0.1（OH）2 at a molar ratio of 1：1.05, followed by sintering at different temperatures. The effects of temperature on the morphology, structure and electrochemical performance were extensively studied. SEM and XRD results demonstrate that the sintering temperature has large influence on the morphology and structure and suitable temperature is very important to obtain spherical materials and suppresses the ionic distribution. The charge-discharge tests show that the electrochemical performance of LiNi0.8Co0.1Mn0.1O2 powders becomes better with the increase of temperature from 700 ℃ to 750 ℃ and higher temperature will deteriorate the performance. Although both of materials obtained at 750 ℃ and 780 ℃ demonstrate almost identical cyclic stability at 2C rate, which delivers 71.9%retention after 200 cycles, the rate performance of powder calcined at 780 ℃ is much poorer than that at 750 ℃. The XRD results demonstrate that the poor performance is ascribed to more severe ionic distribution caused by higher temperature.

Mechanism for capacity fading of 18650 cylindrical lithium ion batteries

The mechanism for capacity fading of18650lithium ion full cells under room-temperature(RT)is discussedsystematically.The capacity loss of18650cells is about12.91%after500cycles.The cells after cycles are analyzed by XRD,SEM,EIS and CV.Impedance measurement shows an overall increase in the cell resistance upon cycling.Moreover,it also presents anincreased charge-transfer resistance(Rct)for the cell cycled at RT.CV test shows that the reversibility of lithium ioninsertion/extraction reaction is reduced.The capacity fading for the cells cycled can be explained by taking into account the repeatedfilm formation over the surface of anode and the side reactions.The products of side reactions deposited on separator are able toreduce the porosity of separator.As a result,the migration resistance of lithium ion between the cathode and anode would beincreased,leading the fading of capacity and potential.

Preparation and Investigation on Lattice Distortion and Electrochemical Performances of Li0.95Na0.05FePO4/C

Na^＋ doped sample Li0.95Na0.05FePO4 was prepared through solid state method. Structure characterization shows Na^＋ is successfully introduced into the LiFePO4 matrix. Scanning electron microscopy shows the particle size mainly ranges in 1-3 μm. X-ray diffraction Rietveld refinement demonstrates lattice distortion with an increased cell volume. As one cathode material, it has a discharge capacity of 150 mAh/g at 0.1 C rate. The material exhibits a capacity of 109 and 107 mAh/g at 5 and 7.5 C respectively. When cycled at 1 and 5 C, the material retains 84% （after 1000 cycles） and 86% （after 350 cycles） of the initial discharge capacity respectively indicating excellent structure stability and cycling performance. Na^＋ doping enhances the electrochemical activity especially the cycle performance effectively.

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.

Dicarboxylate CaC8H4O4 as a high-performance anode for Li-ion batteries

Currently, many organic materials are being considered as electrode materials and display good electrochemical behavior. However, the most critical issues related to the wide use of organic electrodes are their low thermal stability and poor cycling performance due to their high solubility in electrolytes. Focusing on one of the most conventional carboxylate organic materials, namely lithium terephthalate Li2CsH4O4, we tackle these typical disadvantages via modifying its molecular structure by cation substitution. CaCsH4O4 and A12（C8H4O4）3 are prepared via a facile cation exchange reaction. Of these, CaCsH4O4 presents the best cycling performance with thermal stability up to 570℃ and capacity of 399 mA.h.g-1, without any capacity decay in the voltage window of 0.005-3.0 V. The molecular, crystal structure, and morphology of CaCsH4O4 are retained during cycling. This cation-substitution strategy brings new perspectives in the synthesis of new materials as well as broadening the applications of organic materials in Li/Na-ion batteries.

Metastable amorphous chromium-vanadium oxide nanoparticles with superior performance as a new lithium battery cathode

The main drawbacks of vanadium oxide as a cathode material are its low conductivity, low practical capacity and poor cycling stability. Adding Cr can improve its conductivity and a metastable amorphous state may provide higher capacity and stability. In this work, metastable amorphous Cr-V-O nano- particles have been successfully prepared through a facile co-precipitation reaction followed by annealing treatment. As a cathode material for lithium batteries, the metastable amorphous Cr-V-O nanoparticles exhibit high capacity （260 mAh/g at 100 mA/g between 1.5-4 V）, low capacity loss （more than 80% was retained after 200 cycles at 100 mA/g） and high rate capability （up to 3 A/g）.

Carbon-coating-increased working voltage and energy density towards an advanced Na3V2(PO4)2F3@C cathode in sodium-ion batteries

One main challenge for phosphate cathodes in sodium-ion batteries(SIBs)is to increase the working voltage and energy density to promote its practicability.Herein,an advanced Na3V2(PO4)2F3@C cathode is prepared successfully for sodium-ion full cells.It is revealed that,carbon coating can not only enhance the electronic conductivity and electrode kinetics of Na3V2(PO4)2F3@C and inhibit the growth of particles(i.e.,shorten the Na^+-migration path),but also unexpectedly for the first time adjust the dis-/charging plateaux at different voltage ranges to increase the mean voltage(from 3.59 to 3.71 V)and energy density from 336.0 to 428.5 Wh kg^-1 of phosphate cathode material.As a result,when used as cathode for SIBs,the prepared Na3V2(PO4)2F3@C delivers much improved electrochemical properties in terms of larger specifc capacity(115.9 vs.93.5 mAh g^-1),more outstanding high-rate capability(e.g.,87.3 vs.60.5 mAh g^-1 at 10 C),higher energy density,and better cycling performance,compared to pristine Na3V2(PO4)2F3.Reasons for the enhanced electrochemical properties include ionicity enhancement of lattice induced by carbon coating,improved electrode kinetics and electronic conductivity,and high stability of lattice,which is elucidated clearly through the contrastive characterization and electrochemical studies.Moreover,excellent energy-storage performance in sodium-ion full cells further demonstrate the extremely high possibility of Na3V2(PO4)2F3@C cathode for practical applications.

General construction of lithiophilic 3D skeleton for dendrite-free lithium metal anode via a versatile MOF-derived route

The pursuit of high-mileage models results in the recurrence of lithium metal batteries(LMBs)to researchers’horizon.However,the lithium(Li)metal anode for LMBs undergoes the uncontrollable formation of Li dendrites and infinite volume change during cycling,impeding its practical application.To overcome these challenges,we developed a metal-organic framework(MOF)-derived pathway to construct lithiophilic three-dimensional(3D)skeleton using different substrates(e.g.,carbon cloth(CC)and Cu mesh)for dendrite-free lithium metal anodes.As a typical example,the MOF-derived ZnO/nitrogen-doped carbon(NC)nanosheet-modified 3D CC was well-constructed as a lithiophilic hierarchical host(CC@ZnO/NC@Li)for molten Li infiltration.Benefiting from the lithiophilic N-functional groups and LiZn alloy,the synthesized CC@ZnO/NC@Li composite anode promoted the uniform distribution of Li,resulting in a dendrite-free morphology.Meanwhile,the 3D conductive carbon skeleton enhanced the reaction kinetics and buffered the volume change of the electrode.The CC@ZnO/NC@Li composite anode presented a prolonged lifespan of over 1000 cycles at 5 mA cm^(−2) with a low overpotential of 19 mV.Coupled with a LiFePO_(4) cathode,the CC@ZnO/NC@Li composite anode also exhibited superior electrochemical properties in the full-cell system.This versatile strategy may open up the channel of designing multi-functional lithiophilic 3D hosts for the Li metal anode.

Synthesis and electrochemical performance of Sn-doped LiNi_(0.5)Mn_(1.5)O_4 cathode material for high-voltage lithium-ion batteries

ABSTRACT LiNi0.5Mn1.5-xSnxO4 （0≤x≤ 0.1） cathode materials with uniform and fine particle sizes were successfully synthesized by a two-step calcination of solid-state reaction method. As the cathode materials for lithium ion batteries, the LiNi0.5Mn1.48Sn0.0204 shows the highest specific capacity and cycle stability. In the potential range of 3.5-4.9 V at room temperature, LiNi0.5MnL4sSn0.0204 composite material shows a discharge capacity of more than 117 mA h g-1 at 0.1 C, while the corresponding discharge capacity of undoped LiNi0.5Mn1.5O4 is only 101 mA h g-1. Moreover, in cycle performance, all the LiNi0.5Mnl.5-xSnxO4 （0 ≤ x≤ 0.1） samples show better capacity retention than the undoped LiNio.sMnx.sO4 at 1 C rate after 100 cycles. Especially, for the LiNi0.5Mn1.5O4, the discharge capacity after 100 cycles is 90 mA h g-1, while the corresponding discharge capacities of the undoped LiNi0.5Mn1.5O4 is only 56.1 mA h g-1. The significantly enhanced DLi＋ and the enlarged electronic conductivity make the Sn-doped spinel LiNi0.5Mn1.504 material present even more excellent electrochemical performances. These results reveal that Sn-doping is an effective way to improve electrochemical performances of LiNi0.5Mn1.5O4.

Ni-induced stepwise capacity increase in Ni-poor Li-rich cathode materials for high performance lithium ion batteries

Li-rich cathode materials have been considered as promising candidates for high-energy lithium ion batteries （LIBs）. In this study, we report a new series of Li-rich materials （Li[Li1/B-2x/BMn2/3-x/3Nix]O2 （0.09 ≤x≤ 0.2）） doped with small amounts of Ni as cathode materials in LIBs, which exhibited unusual phenomenon of capacity increase up to tens of cycles due to the continuous activation of the Li2MnO3 phase. Both experimental and computational results indicate that unlike commonly studied Ni-doped Li-rich cathode materials, smaller amounts of Ni doping can promote the stepwise Li2MnO3 activation to obtain increased specific capacity and better cycling capability. In contrast, excessive Ni will over-activate the Li2MnO3 and result in a large capacity loss in the first cycle. The Lil.25Mn0.625Ni0.12sO2 material with an optimized content of Ni delivered a superior high capacity of -280 mAh.g-1 and good cycling stability at room temperature.

Mesoporous Fe_(3)O_(4)@C nanoarrays as high-performance anode for rechargeable Ni/Fe battery

Rechargeable aqueous batteries with high power density and energy density are highly desired for electrochemical energy storage.Despite the recent reports of various cathode materials with ultrahigh pseudocapacitance exceeding3000 F g^(-1)(or 800 mA h g^(-1)),the development of anode materials is relatively insufficient,which limits the whole performance of the devices far from practical applications.Herein,we report the preparation of mesoporous Fe_(3)O_(4)@C nanoarrays as high-performance anode for rechargeable Ni/Fe battery by a self-generated sacrificial template method.Zn O/Fe_(3)O_(4)composite was first synthesized by a co-deposition process,and Zn O was subsequently removed by alkali etching to construct the mesoporous structure.A thin carbon film was introduced onto the surface of the electrode by the carbonization of glucose to increase the structural stability of the electrode.The unique mesoporous nanoarray architecture endows the electrode with larger specific surface area,faster charge/mass transport and higher utilization of Fe_(3)O_(4),which shows an ultrahigh specific capacity (292.4 mA h g^(-1)at a current density of 5 mA cm^(-2)) and superior stability in aqueous electrolyte (capacitance retention of 90.8%after 5000cycles).After assembled with hierarchical mesoporous Ni O nanoarray as a cathode,an optimized rechargeable Ni/Fe battery with double mesoporous nanoarray electrodes was fabricated,which provided high energy/power densities(213.3 W h kg^(-1)at 0.658 kW kg^(-1)and 20.7 kW kg^(-1)at113.9 W h kg^(-1),based on the total mass of the active materials)in the potential window of 1.5 V with excellent cyclability(81.7%retention after 5000 charge/discharge cycles).

Polyaniline-modified cetyltrimethylammonium bromide- graphene oxide-sulfur nanocomposites with enhanced performance for lithium-sulfur batteries

Conductive polymer coatings can boost the power storage capacity of lithiumsulfur batteries. We report here on the design and preparation--by combining a facile and green chemical deposition method with an oxidative polymerization approach--of polyaniline （PANI）-modified cetyltrimethylammonium bromide （CTAB）-graphene oxide （GO）-sulfur （S） nanocomposites with significantly enhanced performance in lithium-sulfur batteries. Such conductive polymer modified CTAB-GO-S nanocomposites as sulfur cathode materials can deliver high specific discharge capacities and long-term cycling performance, i.e., -970 mAh-g-1 at 0.2 C and -715 mAh-g-1 after 300 cycles, -820 mAh.g-1 at 0.5 C and -670 mAh.g-1 after 500 cycles, -770 mAh.K at 1 C and -570 mAh.g-~ after 500 cycles. The capacity decay was as low as 0.036% per cycle at 0.5 C, and 0.051% per cycle at 1 C. Under the same condition, batteries using PANI-modified CTAB-GO-S as cathodes exhibited higher specific capacity and higher average coulombic efficiency compared with CTAB-decorated GO-S and GO--S nano- composites. The improved performance can be attributed to the lower charge transfer resistance and the alleviated dissolution of polysulfides in the PANI- modified CTAB-GO-S cathodes.