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1、Development of high-capacity cathode materials with integrated structuresPrincipal Investigator: Sun-Ho Kang Chemical Sciences and Engineering Division Argonne National LaboratoryAnnual Merit Review DOE Vehicle Technologies Program Washington, D.C. May 9-13, 2011This presentation does not contain an
2、y proprietary, confidential, or otherwise restricted informationVehicle Technologies ProgramES0192OverviewTimeline Start date: FY09 End date: On-going Percent complete: - project on-goingBudget Total project funding - 100% DOE Funding in FY10: $300K Funding in FY11: $400KBarriers Low energy density
3、Cost Abuse tolerance limitations Partners Lead PI: Sun-Ho Kang Collaborators: - CSE, Argonne: K. Gallagher, D. Kim, M. M. Thackeray (materials design, synthesis and electrochemical characterization) - APS, Argonne: M. Balasubramanian (XAS) - MIT: C. Carlton, Y. Shao-Horn (TEM) Industrial partners- H
4、anwha Chemical (LiFePO4olivine) - Daejung EM (transition metal precursor)3Objective of this study Design and synthesis of Li- and Mn-rich oxides with integrated structures containing spinel component Performance evaluation and verification of beneficial impact of the spinel component Identification
5、and overcoming of performance degradation issues of high- capacity cathode materials with integrated structure Information exchange and close collaboration with diagnostic study team and PHEV cell building team Supply of promising high-capacity cathode materials for PHEV cell buildDevelopment of cat
6、hode materials with high-capacity, thermal stability, low-cost,and longevity for PHEVs4Milestones FY11Optimization of chemical composition on goingEvaluation of high-capacity electrode materials in full Li-ion configuration using various anode materials on goingIdentification of various issues relat
7、ed with high-capacity cathode materials initiatedInvestigation of the materials structure after cycling by various analytical techniques on goingStudy of physical blending of high-capacity cathode and high-power cathode materials on goingStudy of thermal stability of high-capacity electrode material
8、s on going5ApproachEmbedding spinel component in the layered-layered composite structureSpinel structure can be created in the composite structure by controlling lithium content Lower lithium-to-TM ratio than in xLi2MnO3(1-x)LiMO2First cycle efficiency and rate capability are expected to improve.Ide
9、ntification of challenging issues with high-capacity layered-layered oxide materials (newly added work scope)This type of electrode materials will be used in the ABR PHEV cell build.Voltage profile shape changes (voltage depression) with cycling and Mn dissolution Case- and analytic study Study resu
10、lts will be implemented into the materials design and development efforts.Relatively poor power performance Physical blending of layered-layered oxide with other high-power electrode materials (spinel or olivine) LiFePO4 was chosen because of its low plateau voltage where the high-capacity electrode
11、 shows significantly high impedance.LiMO2(M=Mn,Ni,Co)Li2MnO3LiM2O4 (M=Mn,Ni,Co)6LixMn0.75Ni0.25Oy: Basic E-Chem PropertiesFY11 Technical Accomplishments and Progress1.21.31.41.54060801004.95V4.6VFirst Cycle Efficiency (%)Li content (x)0100200300400500050100150200250300x=1.5x=1.4x=1.3x=1.2Capacity (m
12、Ah/g)Current density (mA/g) LixMn0.75Ni0.25Oyhas the same Mn:Ni ratio (3:1) as 0.5Li2MnO30.5LiMn0.5Ni0.5O2(layered-layered) and LiMn1.5Ni0.5O4(spinel). LixMn0.75Ni0.25Oywas synthesized using Li2CO3and Mn0.75Ni0.25CO3*(850 C, 12 h, air). Coexistence of layered (rhombohedral, monoclinic) and spinel wa
13、s confirmed by X-ray diffraction and HR-TEM (reported last year). For all of the cell test, 2325 separator (tri-layer, Celgard), 1.2M LiPF6in EC:EMC(3:7) were used.1stcycle efficiency1C rate lineRate capability4.6-2.0 V Improvement in the 1stcycle efficiency was achieved by incorporating spinel phas
14、e in the layered- layered matrix. (e.g., 90% for Li1.3Mn0.75Ni0.25Oywhen cycled at 4.6-2.0 V) Some composition (x=1.2) needs initial break-in cycles to reach high capacity. 200 mAh/g at 1C rate was achieved for Li1.2Mn0.75Ni0.25Oy.0102030050100150200250300Capacity (mAh/g)Cycle Numberx=1.5x=1.4x=1.3x
15、=1.2Cycling performanceLi-cell 4.6-2.0 VLi-cellLi-cell*coprecipitated in-house or provided by industrial partner7LixMn0.75Ni0.25Oy: differential capacity plot (4.6-2.0 V)FY11 Technical Accomplishments and Progress2345Voltage (V)1st discharge10th discharge30th discharge2345Voltage (V)1st discharge10t
16、h discharge30th dischargeLi1.2Mn0.75Ni0.25Oy 4.6 2.0 VLi1.3Mn0.75Ni0.25Oy 4.6 2.0 V2345Voltage (V)1st discharge10th discharge30th discharge2345Voltage (V)1st discharge10th discharge30th dischargeLi1.4Mn0.75Ni0.25Oy 4.6 2.0 VLi1.5Mn0.75Ni0.25Oy 4.6 2.0 V Li1.5Mn0.75Ni0.25Oy(or alternatively, 0.5Li2MnO30.5LiMn0.5Ni0.5O2, i.e., spinel-free composition) shows significant dQ/dV change with c
