1、Preparation of Highly-Cyclized Sulfurized Polyacrylonitrile forLithium-Sulfur BatteriesXuan Ji1#,Jia-Yu Wang1#,An-Bang Wang2,Wei-Kun Wang2*,Ming Yao1*,Ya-Qin Huang1*(1.Beijing Key Laboratory of Electrochemical Process and Technology for Materials,Key Laboratory of Biomedical Materials of Natural Mac
2、romolecules,Ministry of Education,Beijing University of Chemical Technology,Beijing 100029,P.R.China;2.Research Institute of Chemical Defense,Beijing 100191,P.R.China)Received:2022-09-15,Revised:2022-10-06.#These authors contributed equally to this work and should be considered as co-firstauthors.*C
3、orresponding author,Wei-Kun Wang,Tel:(86-10)64438266,E-mail: Ming Yao,Yaom-,Ya-Qin Huang,Tel:(86-10)64438266,DOI:10.13208/j.electrochem.2219010Articlehttp:/Cite as:Ji X,Wang J Y,Wang A B,Wang W K,Yao M,Huang Y Q.Preparation of highly-cyclized sulfurized polyacrylonitrilefor lithium-sulfur batteries.
4、J.Electrochem.,2022,28(12):2219010.Abstract:Sulfurized polyacrylonitrile(SPAN)is regarded as an attractive cathode candidate of lithium-sulfur(Li-S)batteries forits non-dissolution mechanism and effective alleviation of polysulfides shuttling issue in Li-S batteries,displaying high utilization ofcat
5、hode active material,outstanding cycle stability and structural stability.However,the relation between cyclization degree and cy-cle stability of SPAN is still unveiled.In this work,SPAN-C-V composites were synthesized by co-introduction of CuSO4and zincn-ethyl-n-phenyldithiocarbamate(ZDB)in the co-
6、heating of sulfur and polyacrylonitrile.The co-introduction of CuSO4and ZDBreduced the cyclization reaction onset temperature of PAN while increased the CC/C=C within SPAN-C-V,thus led to an in-crease in the degree of cyclization of SPAN-C-V,achieving excellent electrochemical performance by simulta
7、neously improving thecyclization degree and increasing the content of sulfur.The SPAN-C-V exhibited an initial reversible capacity of 805 mAhg-1and601 mAhg-1after 100 cycles with the capacity retention rate of 93%at 0.2 C(1 C=600 mAhg-1).The focus on the cyclizationdegree of SPAN provides an enlight
8、enment of advanced cathode material.Key words:sulfurized polyacrylonitrile;CuSO4;zinc n-ethyl-n-phenyldithiocarbamate;cyclization degree;lithium-sulfur battery电 化 学J.Electrochem.2022,28(12),2219010(1 of 11)1 IntroductionAs the next-generation of high specific energy sec-ondary batteries,lithium-sulf
9、ur(Li-S)batteries haveshown high theoretical energydensity(2600 Whkg-1)and high theoretical capacity(1675 mAhkg-1).Moreover,elemental sulfur is abundant in nature,lowtoxicity and low cost of acquiring1-6.Consequently,Li-S batteries are rapidly applied in electric vehicles,military and other fields.N
10、evertheless,there aresome drawbacks in the practical application of Li-Sbatteries.Firstly,the insulating nature of sulfur(510-30Scm-1)hinders electrochemical reactions at afast rate7.Secondly,the discharge products of Li-Sbatteries are soluble in electrolyte,which block thecathode active material fr
11、om subsequent reaction andreduce the utilization of sulfur.More severely,thefurther diffusion to the anode surface will corrode thelithium,causing the bad rechargeable of batteries8.Thus,it is of great significance to develop advancedsulfur cathodes with high energy density and longstable cycle life
12、.High-performance conductive poly-mer-sulfur composites9,such as polypyrrole,poly-acetylene,polyacrylonitrile(PAN),polyaniline andtheir derivatives,have been a risingresearch trend10,11.Polymer-sulfurcompositescanbepreparedbyco-heating sulfur and conductive polymers,since theco-heating with element
13、sulfur(S)can cause the hy-drogen atoms elimination of hydrocarbons and formunsaturated long chains of polymeric pyridine back-bone with conjugated electrons8.Applying the poly-mer-sulfur composites as the active material of Li-Sbatteries can effectively minimize the dissolution ofpolysulfide,improve
14、 the electrochemical perfor-mance,and broaden the application of the batteries.Sulfurizedpolyacrylonitrile(SPAN)wasfirstlypro-posed as a cathode material by Wang et al.8,ob-tained by co-heating S and PAN.As the solid-solidconversion mechanism of SPAN,which is distinctfrom the dissolution and shuttle
15、 of polysulfides oftraditional Li-S batteries,Li-SPAN batteries showgreat cycle stability.Additionally,SPAN shows greatadvantages:(1)high electronic conductivity,(2)suit-able for low cost carbonate electrolyte,(3)Coulombicefficiency close to 100%,and(4)low self-dischargerate,which is only 0.8%after
16、30 days(at 30oC)12.However,the capacity inferior still hinders theprogress of SPAN material,and many outstanding re-search es of promoting SPAN vulcanization havebeen achieved.Inspired by the conventional rubberindustry,vulcanization accelerators were effectivelyapplied to SPAN to increase the S content and furtherimprove the discharge capacity.Chen et al.13em-ployed 2-mercaptobenzothiazoles(MBT)as a vul-canization accelerator,increasing the S content,andimproving the discharge capacity and capa