Nano-alumina@cellulose-coated separators with the reinforcedconcrete-like structure for high-safety lithium-ion batteries

Separators play a critical role in the safety and performance of lithium-ion batteries.However,commercial polyolefin separators are limited by their poor affinity with electrolytes and low melting points.In this work,we constructed a reinforced-concrete-like structure by homogeneously dispersing nano-Al_(2)O_(3) and cellulose on the separators to improve their stability and performance.In this reinforcedconcrete-like structure,the cellulose is a reinforcing mesh,and the nano-Al_(2)O_(3) acts as concrete to support the separator.After constructing the reinforced-concrete-like structure,the separators exhibit good stability even at 200℃(thermal shrinkage of 0.3%),enhanced tensile strain(tensile stress of 133.4 MPa and tensile strains of 62%),and better electrolyte wettability(a contact angle of 6.5°).Combining these advantages,the cells with nano-Al_(2)O_(3)@cellulose-coated separators exhibit stable cycling performance and good rate performance.Therefore,the construction of the reinforced-concretelike structure is a promising technology to promote the application of lithium-ion batteries in extreme environments.

12.6μm-Thick Asymmetric Composite Electrolyte with Superior Interfacial Stability for Solid-State Lithium-Metal Batteries

Solid-state lithium metal batteries(SSLMBs)show great promise in terms of high-energy-density and high-safety performance.However,there is an urgent need to address the compatibility of electrolytes with high-voltage cathodes/Li anodes,and to minimize the electrolyte thickness to achieve highenergy-density of SSLMBs.Herein,we develop an ultrathin(12.6μm)asymmetric composite solid-state electrolyte with ultralight areal density(1.69 mg cm^(−2))for SSLMBs.The electrolyte combining a garnet(LLZO)layer and a metal organic framework(MOF)layer,which are fabricated on both sides of the polyethylene(PE)separator separately by tape casting.The PE separator endows the electrolyte with flexibility and excellent mechanical properties.The LLZO layer on the cathode side ensures high chemical stability at high voltage.The MOF layer on the anode side achieves a stable electric field and uniform Li flux,thus promoting uniform Li^(+)deposition.Thanks to the well-designed structure,the Li symmetric battery exhibits an ultralong cycle life(5000 h),and high-voltage SSLMBs achieve stable cycle performance.The assembled pouch cells provided a gravimetric/volume energy density of 344.0 Wh kg^(−1)/773.1 Wh L^(−1).This simple operation allows for large-scale preparation,and the design concept of ultrathin asymmetric structure also reveals the future development direction of SSLMBs.

Overview of Precious Metal Content Analysis Methods in Automotive Catalytic Converter

With the increasing awareness of environmental protection, people’s concern of pollution issues arising. Vehicles, as the most important means of transportation, its exhaust emission has received considerable attention. The catalytic converter is able to purify harmful substances in exhaust gas. The absolute content of precious metals in the catalytic converter dominates the exhaust gas purification effect. Accurate detection of precious metal content is of great significance for controlling the cost of catalysts, ensuring catalytic performance and recovering precious metals from spent catalysts. We herein summarized several instruments for precious metals content exploration, such as X-ray fluorescence spectrometer (XRF), atomic absorption spectrometer (AAS), inductively coupled plasma emission spectrometer (ICP) and spectrophotometer. In this thesis, the feasibility of using various devices for characterizing precious metal content in catalytic converters is analyzed and their strengths or weaknesses are elaborated.

Composite polymer electrolyte reinforced by graphitic carbon nitride nanosheets for room-temperature all-solid-state lithium batteries

By virtue of the flexibility and safety, polyethylene oxide(PEO) based electrolytes are regarded as an appealing candidate for all-solid-state lithium batteries. However, their application is limited by the poor ionic conductivity at room temperature, narrow electrochemical stability window and uncontrolled growth of lithium dendrite. To alleviate these problems, we introduce the ultrathin graphitic carbon nitride nanosheets(GCN) as advanced nanofillers into PEO based electrolytes(GCN-CPE). Benefiting from the high surface area and abundant surface N-active sites of GCN, the GCN-CPE displays decreased crystallinity and enhanced ionic conductivity. Meanwhile, Fourier transform infrared and chronoamperometry studies indicate that GCN can facilitate Li+migration in the composite electrolyte. Additionally, the GCN-CPE displays an extended electrochemical window compared with PEO based electrolytes. As a result, Li symmetric battery assembled with GCN-CPE shows a stable Li plating/stripping cycling performance, and the all-solid-state Li/LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622) batteries using GCN-CPE exhibit satisfactory cyclability and rate capability in a voltage range of 3-4.2 V at 30 ℃.

中空四氧化三钴纳米球镶嵌的氮掺杂多孔碳纳米纤维:锂-氧电池氧电极双功能催化剂

随着全球人口数量快速增长和科技不断进步,对能源需求逐步增加,但化石能源日渐枯竭,同时环境问题日趋严重.因此,亟需开发新型、绿色、高效的能源以及能源装置,以保障清洁能源的可持续利用.锂-氧电池因其能量密度高、环境友好等优点受到了人们的广泛关注,并被认为是替代锂离子电池的新储能系统之一.然而,对于锂-氧电池仍需解决诸如能量密度低于理论值、倍率性能差和循环寿命短等难题.开发高效稳定的氧电极催化剂是解决上述问题的关键手段之一.在众多潜在的过渡金属氧化物催化剂中,四氧化三钴因其地壳丰度高、成本低和性能优异等优点成为研究热点.本文采用静电纺丝技术,结合热处理技术,成功制备了中空四氧化三钴纳米球镶嵌的多孔碳纳米纤维复合催化剂(H-Co_(3)O_(4)-CNFs),系统地研究了其氧还原反应(ORR)和析氧反应(OER)的电催化性能,以及作为锂-氧电池正极催化剂的电化学性能.结果表明,在碱性电解质中,H-Co_(3)O_(4)-CNFs具有较好的ORR/OER活性,展现出较好的双功能催化性能.H-Co_(3)O_(4)-CNFs作为锂-氧电池的氧电极催化剂材料,在100 mA g^(‒1)电流密度下的过电位为1.35 V,电池的放电比容量达到6134 mAh g^(‒1);当电流密度增加至800 mA g^(‒1)时,放电比容量仍能保持68.5%.在充放电电流密度为100 mA g^(‒1),限制容量为500 mAh g‒1的条件下,电池能保持150圈的稳定循环.H-Co3O4-CNFs催化剂较好的催化性能可归因于:(1)氮掺杂的多孔碳纤维具有良好的导电性和快速的电子传输能力;(2)多孔结构增大了电解液和催化剂活性位点的接触面积,并为放电产物过氧化锂的形成和分解提供了场所.另外,其良好的循环性能得益于裸露的Co_(3)O_(4)和嵌入纤维中的Co_(3)O_(4)形成的两种独立活性位点,这使其在ORR和OER过程中均有可用的催化活性位点,并在放电和充电过程中交替发挥作用.综上,本文研究结果为高效氧电极催化剂的设计提供了新思路。

Bifunctional separator with high thermal stability and lithium dendrite inhibition toward high safety lithium-ion batteries

Coating inorganic ceramic particles on commercial polyolefin separators has been considered as an effective strategy to improve thermostability of separator.However,the introduction of the coating layer could induce pore blockage on the surface of the polyolefin separator.Herein,a ceramic composite layer that consists of alumina nanoparticles(n-Al_(2)O_(3))and halloysite nanotubes(HNTs)is designed to modify the polyethylene(PE)separator(the modified separator is denoted as AH-PE).The HNTs with hollow nanotubular structure construct a light skeleton and provide fast ion transport channels while Al_(2)O_(3)particles function as heat-resistant fillers to inhibit the shrinkage of the separator at elevated temperatures.The total thickness of AH-PE separator is only 14μm.Consequently,the mass increment of AH-PE separator decreases from 5 g/m^(2)to 3.5 g/m^(2),and the Gurley value reduces by 23%,compared with Al_(2)O_(3)coated PE separator(A-PE).Due to the synergistic effects of Al_(2)O_(3)and HNTs,AH-PE separator exhibits highly improved thermal stability(almost no shrinkage at 170℃for 30 min),high Li^(+)transference number(up to 0.47),and long cycle life of 450 h for Li|Li cells.Moreover,the Li Fe PO_(4)/Li cells assembled with AH-PE separators demonstrate improved rate capability and safety performance.

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.

A Novel Aminoalkylsilane Compound with Oligo(ethylene oxide) Units as Effective Additive for Improving Cyclability of Lithium-ion Batteries

A new aminoalkylsilane compound, （（2-（2-（N,N-dimethylamino）ethoxy）ethoxy） methyl）trimethylsilane （TMSC1N2） based on the oligo（ethylene oxide） chain end-capped with organosilicon functional group and alkylamine group on each end, was introduced as an electrolyte additive for lithium-ion batteries. Electrochemical performances of different volume ratios of TMSC1N2 in the baseline electrolyte were conducted through cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge/ discharge tests of lithium-ion batteries. With adding 5 vol.% TMSC1N2 to the baseline electrolyte （1 mol/L LiPF6 in ethylene carbonate and diethyl carbonate （EC：DEC = 1：1, in volume））, the capacity retention of LiFePO4/Li cells could be significantly improved from 74.7% to 90.8% after 130 cycles. Furthermore, TMSC1N2 showed good compatibility with graphite electrode and would not deteriorate the electrochemical performance of graphite/Li anode cells. These data suggested that TMSC1N2 could be utilized as an effective additive for lithium-ion batteries.