A phase inversion based sponge-like polysulfonamide/SiO_2 composite separator for high performance lithium-ion batteries

In this work,a sponge-like polysulfonamide(PSA)/SiO_2 composite membrane is unprecedentedly prepared by the phase inversion method,and successfully demonstrated as a novel separator of lithium-ion batteries(LIBs).Compared to the commercial polypropylene(PP) separator,the sponge-like PSA/SiO_2 composite possesses better physical and electrochemical properties,such as higher porosity,ionic conductivity,thermal stability and flame retarding ability.The LiCoO_2/Li half-cells using the sponge-like composite separator demonstrate superior rate capability and cyclability over those using the commercial PP separator.Moreover,the sponge-like composite separator can ensure the normal operation of LiCoO_2/Li half-cell at an extremely high temperature of 90 °C,while the commercial PP separator cannot.All these encouraging results suggest that this phase inversion based sponge-like PSA/SiO_2 composite separator is really a promising separator for high performance LIBs.

LiFePO_(4) as a dual-functional coating for separators in lithium-ion batteries:A new strategy for improving capacity and safety

Lithium-ion batteries(LIBs)require separators with high performance and safety to meet the increasing demands for energy storage applications.Coating electrochemically inert ceramic materials on conventional polyolefin separators can enhance stability but comes at the cost of increased weight and decreased capacity of the battery.Herein,a novel separator coated with lithium iron phosphate(LFP),an active cathode material,is developed via a simple and scalable process.The LFP-coated separator exhibits superior thermal stability,mechanical strength,electrolyte wettability,and ionic conductivity than the conventional polyethylene(PE)separator.Moreover,the LFP coating can actively participate in the electrochemical reaction during the charge-discharge process,thus enhancing the capacity of the battery.The results show that the LFP-coated separator can increase the cell capacity by 26%,and improve the rate capability by 29%at 4 C compared with the conventional PE separator.The LFP-coated separator exhibits only 1.1%thermal shrinkage at 140°C,a temperature even above the melting point of PE.This work introduces a new strategy for designing separators with dual functions for the next-generation LIBs with improved performance and safety.

Dynamic Multi-Physics Behaviors and Performance Loss of Cylindrical Batteries Upon Low-Velocity Impact Loading

In challenging operational environments,Lithium-ion batteries(LIBs)inevitably experience mechanical stresses,including impacts and extrusion,which can lead to battery damage,failure,and even the occurrence of fire and explosion incidents.Consequently,it is imperative to investigate the safety performance of LIBs under mechanical loads.This study is grounded in a more realistic coupling scenario consisting of electrochemical cycling and low-velocity impact.We systematically and experimentally uncovered the mechanical,electrochemical,and thermal responses,damage behavior,and corresponding mechanisms under various conditions.Our study demonstrates that higher impact energy results in increased structural stiffness,maximum temperature,and maximum voltage drop.Furthermore,heightened impact energy significantly influences the electrical resistance parameters within the internal resistance.We also examined the effects of State of Charge(SOC)and C-rates.The methodology and experimental findings will offer insights for enhancing the safety design,conducting risk assessments,and enabling the cascading utilization of energy storage systems based on LIBs.

Rational design on separators and liquid electrolytes for safer lithium-ion batteries

As the energy density of lithium-ion batteries (LIBs) continues to increase,their safety has become a great concern for further practical large-scale applications.One of the ultimate solution of the safety issue is to develop intrinsically safe battery components,where the battery separators and liquid electrolytes are critical for the battery thermal runaway process.In this review,we summarize recent progress in the rational materials design on battery separators and liquid electrolyte towards the goal of improving the safety of LIBs.Also,some strategies for further improving safety of LIBs are also briefly outlooked.

Safer Lithium-Ion Batteries from the Separator Aspect:Development and Future Perspectives

With the rapid development of lithium-ion batteries(LIBs),safety problems are the great obstacles that restrict large-scale applications of LIBs,especially for the high-energy-density electric vehicle industry.Developing component materials(e.g.,cathode,anode,electrolyte,and separator)with high thermal stability and intrinsic safety is the ultimate solution to improve the safety of LIBs.Separators are crucial components that do not directly participate in electrochemical reactions during charging/discharging processes,but play a vital role in determining the electrochemical performance and safety of LIBs.In this review,the recent advances on traditional separators modified with ceramic materials and multifunctional separators ranging from the prevention of the thermal runaway to the flame retardant are summarized.The component–structure–performance relationship of separators and their effect on the comprehensive performance of LIBs are discussed in detail.Furthermore,the research challenges and future directions toward the advancement in separators for high-safety LIBs are also proposed.

A polyethylene microsphere-coated separator with rapid thermal shutdown function for lithium-ion batteries

Thermal runaway is the main factor contributing to the unsafe behaviors of lithium-ion batteries(LIBs)in practical applications.The application of separators for the thermal shutdown has been proven as an effective approach to protecting LIBs from thermal runaway.In this work,we developed a thermal shutdown separator by coating a thin layer of low-density polyethylene microspheres(PM)onto a commercial porous polypropylene(PP)membrane and investigated the thermal response behaviors of the as-prepared PM/PP separator in LIBs.The structural and thermal analysis results revealed that the coated PM layer had a porous structure,which facilitated the occurrence of normal charge-discharge reactions at ambient temperature,although it could melt completely and fuse together within very short time periods:3 s at 110℃and 1 s at 120℃,to block off the pores of the PP substrate,thereby cutting off the ion transportation between the electrodes and interrupting the battery reaction.Consequently,the PM/PP separator exhibits very similar electrochemical performance to that of a conventional separator at ambient temperature.However,it performs a rapid thermal shutdown at an elevated temperature of^110℃,thus controlling the temperature rise and maintaining the cell in a safe status.Due to its synthetic simplicity and low cost,this separator shows promise for possible application in building safe LIBs.

Thermal Stability and Electrochemical Properties of Separators for Lithium-ion Batteries

The mechanical properties,contact angle,thermomechanical and electrochemical properties of PE,PVDF,and ceramic separators were compared.The experimental results show that the PE separator has the largest porosity,the PVDF separator has the best mechanical properties,wettability,and heat resistance.Three kinds of separators were assembled into lithium-ion batteries for electrochemical tests.Among them,the PE separator has the best rate performance,and the ceramic separator has poor performance in charge-discharge cycles.At the same time,the PE and ceramic separators were tested with different amounts of electrolytes at room temperature and a high temperature,and it is found that the capacity of the PE separator is higher at room temperature,while the performance of the ceramic separator is better at a high temperature.The amount of electrolyte also has a certain influence on its electrochemical performance.

Regulating the growth of lithium dendrite by coating an ultra-thin layer of gold on separator for improving the fast-charging ability of graphite anode

With the ever-growing application of lithium-ion batteries(LIBs), their fast-charging technology has attracted great interests of scientists. However, growth of lithium dendrites during fast charge of the bat teries with high energy density may pose great threats to the operation and cause serious safety issues Herein, we prepared a functional separator with an ultra-thin(20 nm) layer of Au nanoparticles deposited by evaporation coating method which could regulate growth direction and morphology of the lithium dendrites, owing to nearly zero overpotential of lithium meal nucleation on lithiated Au. Once the Li den drites are about to form on the graphite anode during fast charging(or lithiation), they plate predomi nantly on the Au deposited separator rather than on the graphite. Such selective deposition does no compromise the electrochemical performance of batteries under normal cycling. More importantly, i enables the better cycling stability of batteries at fast charge condition. The Li/Graphite cells with Au nanoparticles coated separator could cycle stably with a high areal capacity retention of 90.5% over 95 cycles at the current density of 0.72 m A cm^(-2). The functional separator provides an effective strategy to adjust lithium plating position at fast charge to ensure high safety of batteries without a compromise on the energy density of LIBs.

Recent progress on lithium-ion batteries with high electrochemical performance

Lithium-ion batteries(LIBs) have been widely used in many fields such as portable electronics and electric vehicles since their successful commercialization in the 1990 s. However, the electrochemical performance of current commercial LIBs still needs to be further improved to meet the continuously increasing demands for energy storage applications. Recently, tremendous research efforts have been made in developing next-generation LIBs with enhanced electrochemical performance. In this review, we mainly focus on the recent progress of LIBs with high electrochemical performance from four aspects, including cathode materials, anode materials, electrolyte, and separators. We discuss not only the commercial electrode materials(LiCoO_2,LiFePO_4, LiMn_2O_4, LiNi_xMn_yCo_zO_2, LiNi_xCo_yAl_zO_2, and graphite) but also other promising next-generation materials such as Li-, Mn-rich layered oxides, organic cathode materials, Si, and Li metal. For each type of materials, we highlight their problems and corresponding strategies to enhance their electrochemical performance. Nowadays, one of the key challenges to construct high-performance LIBs is how to develop cathode materials with high capacity and working voltage. This review provides an overview and future perspectives to develop next-generation LIBs with high electrochemical performance.

A comparative study on polypropylene separators coated with different inorganic materials for lithium-ion batteries

Coating commercial porous polyolefin separators with inorganic materials can improve the thermal stability of the polyolefin separators and hence improve the safety of lithium-ion batteries. Several different inorganic materials have been studied for the coating. However, there lacks a study on how different the properties of separators, in inorganic materials affect terms of thermal stability and cell performance. Herein, we present such a study on coating a commercial polypropylene separator with four inorganic materials, i.e., Al2O3, SiO2, ZrO2 and zeolite. All inorganic coatings have improved thermal stability of the separators although with differences. The coating layers add 28%-45% of electrical resistance compared with the pure polypropylene separator, but all the cells prepared with the coated polypropylene separators have the same electrical chemical performance as the uncoated separator in terms of rate capability and capacities at different temperatures.

High safety separators for rechargeable lithium batteries

Lithium-ion batteries(LIBs)are presently dominant mobile power sources due to their high energy density,long lifespan,and low self-discharging rates.The safety of LIBs has been concerned all the time and become the main problem restricting the development of high energy density LIBs.As a significant part of LIBs,the properties of separators have a significant effect on the capacity and performances of batteries and play an important role in the safety of LIBs.In recent years,researchers devoted themselves to the development of various multi-functional safe separators from different views of methods,materials,and practical requirements.In this review,we mainly focus on the recent progress in the development of high-safety separators with high thermal stability,good lithium dendritic resistance,high mechanical strength and novel multifunction for high-safety LIBs and have in-depth discussions regarding the separator's significant contribution to enhance the safety and performances of the batteries.Furthermore,the future directions and challenges of separators for the next-generation high-safety and high energy density rechargeable lithium batteries are also provided.

Multifunctional robust aerogel separator towards high-temperature,large-rate,long-cycle lithium-ion batteries

Separators is indispensable for the normal operation of lithium-ion batteries(LIBs).However,the widely used commercial polyolefin separators have some inherent deficiencies such as poor thermotolerance,high inflammability and inferior electrolyte wettability,which restrict their further applications of the advanced and safe batteries.Herein,we design a novel thermotolerant(a shrinkage percentage of 0%at 300℃)and flame retarded aerogel separator consisting of aramid nanofibers(ANFs).Because of its high porosity(86.5%±6.1%)and excellent electrolyte uptake(695%),the ANFs aerogel separator has an ionic conductivity of 1.04 mS/cm and a high lithium-ion transference number(0.67),which can endow LIBs with outstanding rate performance and superior cycling performance.Specifically,the ANFs aerogel separator-based batteries possess a discharge specific capacity of 102 m Ah/g with a capacity retention of 90.7%and a Coulombic efficiency of 99.3%after 600 cycles at 5 C.In addition,under an operated temperature of 90℃,the battery with ANFs aerogel separator can still conduct the very steady chargedischarge,presenting a capacity retention of 90.1%and a Coulombic efficiency of 99.6%after 200 cycles at 3 C.Accordingly,the separator can probably serve as a potential candidate for application to advanced and safe LIBs.

隔膜对18650型锂离子电池性能的影响

用4种隔膜制作了18650型锂离子电池,并测试了电池的安全性能(150℃热箱、冲击和过充实验)和电性能(倍率和循环性能)。隔膜的孔隙率大、熔融温度高,电池的150℃热箱安全性能坚持时间就短,而2C、12 V过充安全性能和倍率放电性能更好。孔隙率值合适(约45%)和孔径均匀的隔膜,能提高电池的循环性能。

车用锂离子电池隔膜特性的试验研究

选取了4种锂离子电池的商品化隔膜产品,采用傅立叶变换红外光谱仪、X射线衍射仪和扫描电子显微镜等手段,对隔膜材料的组成和结构特性进行表征;采用热重分析仪和差示扫描量热仪,对隔膜材料的热性能进行分析;同时,进行隔膜材料的机械性能、耐热性能和吸液性的试验。结果表明,非聚烯烃类隔膜具有较好的耐热性能,但机械性能较差。

Al2O3陶瓷改性隔膜的安全性能

以聚乙烯(PE)隔膜和Al2O3陶瓷涂覆改性PE隔膜组装软包装锂离子电池。通过SEM、热收缩、穿刺、外短路和过充等测试,研究Al2O3陶瓷涂覆改性PE隔膜的安全性能PE隔膜经Al2O3陶瓷涂覆改性后,耐热性能和浸润性能提升,组装的电池在穿刺测试中最高温度仅135t,外短路和过充测试表现也更好。改性隔膜组装的电池在室温下于2.75-4.20V以0.5C充电、1.0C放电循环555次,容量保持率在90.86%以上,80%放电深度预计寿命在1200次以上。

隔膜对锂离子电池针刺安全性的影响

为研究聚乙烯(PE)隔膜的特性与锂离子电池针刺安全性的关系,选择20μm厚的隔膜A(韩国产)、隔膜B(河北产)和隔膜C(江苏产),通过SEM、拉伸强度、透气度和热收缩等方法,进行基本的物理性能对比,发现断裂伸长率是主要差别。隔膜A、隔膜B和隔膜C的纵向(MD)伸长率分别为100.8%、161.7%和115.3%;横向(TD)伸长率分别为79.8%、123.7%和124.2%。制备的软包装锂离子电池均通过了针刺测试。分析针刺过程中的电压降及对比针刺后隔膜孔的大小可知,隔膜A、隔膜B和隔膜C制备的电池的平均电压降分别为0.673 mV、0.143 mV和0.170 mV,隔膜A制备的电池的电压降最大,且隔膜A的针刺孔较大。这表明,隔膜的断裂伸长率越大,电池的针刺安全性越好。

基于复合隔膜的高安全性锂离子电池

隔膜对锂离子电池的安全性能有重要影响。聚丙烯(PP)、聚乙烯(PE)等商用隔膜的熔点偏低,在高温下会发生熔化,导致大面积内短路,引发电池热失控。将SiO 2/聚乙烯醇(PVA)浆料直接涂覆在电极表面,形成电极支撑型复合隔膜,取代传统的PP/PE隔膜,以提升电池的安全性能。复合隔膜厚度约为30μm,在400℃下不发生收缩形变,制备方法与现有电池生产线匹配较好,可实现锂离子电池的规模化量产。基于负极支撑型复合隔膜的20 Ah软包装电池,以0.5 C的电流在2.50~3.65 V循环500和1000次后,容量保持率分别为95%和88%。在200℃、300℃加热测试中,电池不发生热失控;针刺测试中,电池表面最高温度仅为36℃,且无鼓胀现象。

锂离子电池聚烯烃隔膜安全性能的探讨

锂离子电池的使用安全性广受关注。本文试图从锂离子电池结构、工作原理以及安全问题引发机理方面入手,提出电池安全设计对聚烯烃隔膜的性能需求,并分析探讨了不同聚烯烃隔膜的安全性能。

高安全性锂离子电池隔膜发展现状

隔膜对于锂离子电池安全性具有十分重要的影响.该文综述了聚烯烃隔膜高性能化、聚烯烃隔膜改性以及新型隔膜技术,并对现有方法进行了评述,对锂离子电池隔膜发展方向进行了展望,最后提出,隔膜原材料和改性技术对高安全性锂离子电池开发具有较大的潜力.

动力锂离子电池隔膜的性能要求及发展状况

介绍了动力锂离子电池对隔膜的性能要求,分析了现有的聚烯烃隔膜的特点及缺陷,并综述了目前各类型动力锂离子电池隔膜的研究成果,讨论了改性聚烯烃隔膜、改性无纺布隔膜及其他隔膜的特点及应用情况。另外,指出了安全性及均一性是动力锂离子电池隔膜的最基本要求及关键性能。