锂离子电池的碳导电添加剂

1、Outline 大纲大纲1. Introduction (介绍） Why carbon materials as conductive matrix? 为什么碳材料可以作为导电体为什么碳材料可以作为导电体 Role of the carbon conductive matrix,碳导电体的作用2. Graphite as conductive additive 石墨作为导电添加剂3. Carbon black as conductive additive 碳黑作为导电添加剂4. Graphite or carbon black? 选择石墨还是碳黑5. Conclusions 结论 electr

2、ical conductivity 导电性 thermal conductivity (graphite in particular) 导热性(特别是石墨) non-toxic and environmentally begnin无毒环境友好 available in high quantity and purity高纯度 chemically inert化学稳定性 low weight 低重量 relatively low production costs 相对低的制造成本 (Xylene density: 2.230-2.267 g cm-3, 二甲苯密度 graphite interla

3、yer distance石墨层距 c/2: 0.3354-0.3360 nm)1. Electrode impedance optimization电阻的最优化 Increase of the electronic conductivity增加导电性(mathematically described by the Percolation Theory or the Effective Medium Theory渗透理论的数学描述) Ultimate resistivity level最终的电阻率Percolation curve渗透曲线渗透曲线r r W W*cm0.11vol.% C5101

4、5Slope 斜率Resistivity level of the electrode material电极的导电Limits for thin film electrodes, but suitable for material comparisons对薄膜电极有局限性,但适用材料的比较 Increase of the ionic conductivity增加离子导电性 (electrolyte retention and lithium ion transport rate in the electrode pores 电解液的保持和在电极孔中锂离子的传送速率)- electrolyte

5、absorption 电解液的吸收- control of electrode pore structure电极多孔结构的控制2. Energy density optimization能量密度的最优化 electrode density (compaction properties)电极密度(压实性) electrolyte and polymer binder content (polymer/electrolyte absorption) 电解质和高分子粘接剂的含量电解质和高分子粘接剂的含量 electrochemical and chemical side reactions (sur

6、face area) 电化学和化学副反应电化学和化学副反应3. Electrode manufacturing process (slurry preparation)电极生产过程(制浆)- viscosity control of the slurry (solvent absorption)浆料的粘度控制- dispersibility in the liquid media分散在液体介质中1. Electrode impedance optimization电极电阻的最优化Properties性能c/2=. 3354 nm0 a=0.246 nml=0.1421 nmABAPrismat

7、ic SurfaceBasal Plane SurfaceHexagonalRombohedralABCAc=1.0072 nmGraphite crystal structure石墨的晶体结构1 mmGraphite texture石墨质地Graphite porosity surface roughness 表面粗糙度 porosity 多孔性 geometrical surface area 几何表面积Total graphite surface area石墨表面积 surface defects 表面缺陷0.00.20.40.60.81.00246810 Vads. cm3Pressu

8、re p/760 TorrN2-adsorptionN2-desorptionBCathode barUII456789100.00.20.40.60.81.01.21.4 电阻电阻 W W cm石墨含量石墨含量 % KS6 KS15 SFG15 MX15020406080100100150200250300350400 Specific charge mAh/gCycle number Li+ insertion Li+ de-insertionMCMB/SFG6MCMBElectrolyte:1 M LiPF6 in EC/DMC (1:1)Graphite additives in th

9、e negative electrode石墨在负极中Binder: 10 % PVDF01002003004000.00.20.40.60.81.01.21.4 Specific Charge mAh/g CarbonPotential vs. Li/Li+ V1 M LiPF6 in EC/DMC 1:1 (w:w)10 % PVDF binderTIMREX SFG44Double function intercalation host双重功效嵌入主体0246810121416182002468101214161820222426 Irreversible Capacity %Specif

10、ic BET Surface Area m2/g KS-type SFG-type T-type SLM-type SLX-type NP-typeInfluence of the specific BET surface area比表面积的影响1 M LiPF6 in EC/DMC 1:1 (w:w)10 % PVDF binderCompatibility with propylene carbonate丙烯碳酸盐的相容性0.00.51.01.52.00.00.51.01.5 Potential vs. Li/Li+ Vx in LixC6SFG6SFG15SFG44Electrolyte

11、:1 M LiPF6 in EC/PC 1:1 (w:w)0510152025050100150200250 DBPA g/100 g C BET SSA m2 g-1Isometric各向同性Anisometric各向异性Electrode density increase电极密度增加0400800120016000.81.21.62.02.4 Press Density g/cm3Pressure kg/cm2 MCMB SFG15 MCMB+20 % SFG15graphite real density Vapor grown fibers气相生长碳纤维50 nm500 nmCarbon

12、 nanotubes碳纳米管 electric conductivity导电 thermal conductivity导热 flexural modulus弯曲模量 Thermal process热过程Cracking裂化:CxH2x+z + Energy CxHy + (x + z/2 - y/4) H2 (zy)Synthesis合成: CxHy x C + y/2 H2Separated process steps of heat generation and carbon black formation热产生和碳黑形成的过程 Acetylene process乙炔化n C2H2 2n

13、C + n H2 + Energy carbon black formation at temperatures below 2000 Cabove 2000 C partial graphitization occurs. 在2000 C形成碳黑, 2000 C以上部分石墨化Cracking:裂解CxH2x+z + Energy CxHy + (x + z/2 - y/4) H2 (zy)Synthesis:合成 CxHy x C + y/2 H2Combustion燃烧:CxH2x+z + (3x/2 + z/4) O2 x CO2 + (x + z/2) H2O + EnergyCrac

14、king:裂解CxH2x+z + Energy CxHy + (x + z/2 - y/4) H2 (zy)Synthesis:合成 CxHy x C + y/2 H21.Vaporization of the feed stock and pyrolysis down to C1 and C2 units气化原料和高温裂解成C1和C2 2. Formation of nuclei or growth centers for primary carbon particles 原碳粒子的生长中心或核的形成3. Growth and fusion of the nuclei to concentr

15、ic primary particles核的生长和融合成同心的原生碳颗粒4. Agglomeration of the primary particles to primary aggregates原生颗粒集聚成原生集聚体5. In some cases a secondary growth: formation of pyrolytic deposit on the agregate surface,在某些情况下,二次生长: 在聚集体表面热解沉积的形成6. Agglomeration of the aggregates by van-der-Waals forces 聚集体因范德华力而团聚7

16、. Eventual aggregation of the agglomerates followed by subsequent coating of carbon observed in the plasma process 团聚体的最后形成,跟随着在等离子过程中可以观测到的碳涂覆Partial Oxidation部分氧化Carbon Separation碳分离CarbonTreatment碳处理Oil油GasTreatment气化处理Silos料仓Oxidant氧化剂GranulatingPackaging造粒包装Burning燃烧End userH2PalletisingWarehou

17、se装盘,仓储De-dusting去尘TIMCAL carbon black-schematic process flow diagram特密高碳黑生产流程特密高碳黑生产流程ENSACOTM 250Acetylene black乙炔黑(Origin: University of Louvain, Belgium)20 nm20 nmTransition electron microscopy (TEM)(Origin: Prof. Donnet, Mulhouse)Scanning tunneling microscopy(STM)Acetylene black10 x10 nmENSACOT

18、M 25010 x10 nmENSACOTM 2505x5 nm(Origin: University of Louvain, Belgium)TEM picture of ENSACOTM 25050 nmHigh structure高结构high void volume高空隙 high oil absorption number (OAN)高吸油值 high DBP absorption高DBP值OAN 170 mL/100 gLow structure低结构low void volume低空隙CB aggregate碳黑聚集体with a high degree of openness

19、and chaining高空间和链结构05010015020011.21.41.61.82Ensaco 250Acetylene blackCompression energythicknessCompression energy kg cmThickness cm05010015020011.21.41.61.82Ensaco 250Acetylene blackCompression energythicknessCompression energy kg cmThickness cm00.050.10.150.20.250.30.50.60.70.80.91Ensaco 250Acety

20、lene blackResistivity (ohm.cm)densityCompression energy kg cmPress density g cm-300.050.10.150.20.250.30.50.60.70.80.91Ensaco 250Acetylene blackResistivity (ohm.cm)densityCompression energy kg cmPress density g cm-3Thickness厚度厚度 cmPress density 压实密度压实密度g cm-3Compaction behavior压缩行为Compaction energy

21、压缩能压缩能kg cmCompaction energy kg cmENSACO 250Acetylene blackENSACO 250Acetylene blackTEM of ENSACOTM 35050 nm Crystallite Edges 晶体边 Graphitic石墨面 Planes Amorphous Carbon 无定型碳 Slit Shaped Cavities 裂口空隙 I I II II III III IV IV Surface heterogeneity and surface microstructure表面异质和微结构Surface group chemist

22、ry表面功能团化学 (Temperature-controlled thermodesorption)Carbon black碳黒H2mmole g-1H2Ommole g-1COmmole g-1CO2mmole g-1SuperTM P91.8214.14.6ENSACOTM 350 uperTM PAcetylene B.乙炔黑乙炔黑Ash %灰分0.010.06Volatiles %挥发物0.100.16Toluene extractables %甲苯析出0.030.05Sulfur ppm硫7618002468101214Sulphates Chlorine

23、sFluorines BrominesNitrates PhosphatesANIONIC IMPURITIESEnsaco 250Acetylene blackppm SO42-Cl-F-Br-NO3-Pontent ppmppmSuperTM PAcetylene B.Al0.81.3Ca8.41.2Co0.10.1Cr24.6Cu0.20.3Fe841K0.50.5Mg10.3Mn0.10.1Mo0.50.5Na82.1Ni0.53.9V0.20.2Zn0.51.2 Carbon blacks with higher structure show perc

24、olation threshold at lower carbon content高结构碳黑的渗透值较低 The higher the OAN is the less carbon black is needed for a given resitivity level of the electrode达到同样的导电值吸油值大的碳黑需要量小246810121416048121620 Resistivity W W cmC content % ENSACOTM 350 G ENSACOTM 250 G SUPERTM P+ LiMn2O424681012141602468101214 Resis

25、tivity W W cmC content % SUPER PTM ENSACOTM 350G ENSACOTM 250 G+ LiCoO205010015020025030035040002004006008001000Structure结构结构(DBP absorption)Specific surface area 比表面积比表面积 (m/g)MMM Process/MMM法法Furnace Process炉黑炉黑Thermal Process热黑热黑AcetyleneBlack乙炔黑乙炔黑GaseificationProcess气化法气化法Channel Process/槽黑槽黑Af

26、tertreated furnaceLamp Process灯黑灯黑 High polymer binder absorption decreases mechanical electrode stability 吸收更多的粘合剂会降低电极的机械稳定性 High electrolyte absorption could lead to strong swelling of the electrode 高电解液的吸收会导致电极的膨胀 High viscosity of the electrode slurry/higher demand of solvent 电极的高粘度需要更多的溶剂 High

27、 surface area leads to chemical and electrochemical side reactions especially in the charged state of the electrodes 高比表面积会导致化学和电化学的副反应.特别是在充电状态- Higher specific charge losses in the negative electrode related to SEI formation due to increased electrode area在负极中的更高的比电荷损失.这是由于表面积增加导致SEI的形成-Higher ele

28、ctrolyte oxidation rate at the charged positive electrode 正极充电时的电解液高氧化率- Higher dissolution rate of manganese in the electrolyte in the case of a LiMn2O4 spinel positive electodes尖晶石电极下,在电解液中的Mn的高溶解 Effects depend on the carbon concentration and might be negligible 这些效应取决于碳黑浓度,也可能被忽略.Absorption stif

29、fness changes in an intensive mixer在强搅拌下的吸收硬度0.00.51.01.52.005101520253035 Absorption stiff ness吸收硬度吸收硬度 mL/5 gTreatment time处理时间处理时间 ENSACOTM 260 Knapsack SuperTM S SuperTM P Denka200 nm200 nmSUPERTM PTIMREX KS45 mmLiCoO2 positive electrode正极Graphite negative electrode石墨负极5 mmSUPERTM P/TIMREX KS6 (

30、1:4) conductive matrix/1:4的SUPERP/KS6Hong et. al. have suggested binary 1:1 mixtures / Hong 等建议1:1的混合(Journal of Power Sources, 111 (2002) 90-96.)LiCoO2 positive electrode正极Graphite negative electrode负极Capacity retention during cycling循环过程中的能量保持0204060801000100200300400 Specific charge mAh g-1Cycle

31、Number no additive 8 % KS6/2 % Super P 4 % KS6/1 % Super P02040608010004080120160200 3 % Super P/2 % KS4 5 % Super PSpecific charge mAh g-1Cycle numberGraphite and carbon black are complementary products石墨和碳黑是相互补充的产品Cell parameters电池参数电池参数Carbon black碳黑碳黑Graphite石墨石墨Electric electrode conductivity电极导电Particle-particle contact and contact to collector颗粒和颗粒,以及和集流器的接触Conductive paths thorugh electrode通过电极的导电途径Ionic electrode conductivity离子电极导电Electrolyte absorption电解液吸收Porosity control孔的控制Cycling stability循环稳定性Flexible network适应性的网络Optima