201006 studies on low cost and safe lithium ion batteries for electric vehiclePresentation Transcript
Studies on low cost and safe Lithium-Ion Batteries for Electric Vehicle Supervisor: Prof.Nerino Penazzi Prof.Qiuping chen Ph.D Student Xi Zhixia 2010-06
◆ Develop the low cost and safe Lithium-Ion Batteries for electric vehicles (EVs) and hybrid electric vehicles (HEVs) though: - employing the system of Li （ Co ， Ni ， Mn ） O2 as cathode material; - hydrothermal technique ; Funded by ANHUI JIANGHUAI AUTOMOBILE CO.,LTD Aim of the study
Motivation of the study - Existing problems of the battery for EVs; 1. High cost 2. High toxicity, 3. Not safety -H uge demand from the vehicle Market for low cost and safety batteries for EVs Motivation of the study
Reference : BCG research group World state of art : Characteristics of commercial available Li-Ion batteries
Cathodes materials studied in literatures and performance comparison between them: Li （ Ni ， Mn ） O2 system employed by this study are low cost and thermal stable, however it is difficult to sintered , and the Electric capacity of them needs to be further improved--- objective of this study. World state of art about cathodes materials Cathode material LiCoO2 LiNiO2 LiMnO4 toxicity high low low cost high medium low thermal stability good not good best Electric capacity high high medium re-generation(cycle) best good good Synthesis easy medium difficult
World state of art about techniques used for cathodes materials synthesis Technique proposed for this study is : hydrothermal technique Patent Filing date Subject Component Method Characteristics of the materials WO 2007/048142 From USA 2006 LITHIUM ION BATTERIES anode : Li 4 Ti 5 O 12 Nano-crystalline Cathode: LiMn 2 O 4 Nano-crystalline hydrothermal conversion Rapid recharge, ≥10C; longer battery life 1000 cycle; inherently safe operation US 7390472 2000 Method of making nanostructured lithium iron phosphate-based powders with an olivine type structure hydrothermal conversion high power density, low cost and environmentally benign rechargeable Li-ion batteries. US6048645 2007 Method of preparing lithium ion electrochemical cells Li2Mn2O4 high temperature solid-state method “ excess lithium ” WO 2007/120347 USA 2007 SILICON-CONTAINING ALLOYS USEFUL AS ELECTRODES FOR LITHIUM-ION BATTERIES Anod: SixSnqMyCz LiMnO2 Cathode:C Ball Milling?? exhibit good cycle life and coulombic efficiency. US6048645 2006 lithium-nickel-cobalt-manganese containing composite oxide LipNixMn1-x-yCoyO2-qFq high temperature solid-state method wide usable voltage range, high capacity and safety.
Innovation of this study 1. Low cost cathodic materials used 2. Techniques for forming nanostructured cathodic materials will be used at low and high temperature in order to : - increase of the active material efficiency Enhancement of the surface area via synthesis of Nanostructured oxides: small particle size or porous particles - decrease the oxides low electronic conductivity thin and homogeneous carbon layer formation on the grain surface during synthesis
Organization of this study Component study Cell assembly Module production Pack production Vehicle use Anode, cathode active materials study Assembly and production single cell The lifecycle study, interface study Integration with battery management system that control power, charging temperature etc. Configuration cells into larger module to improve its performance
The procedure used for the preparation of LixMnyOz: Starting from potassium permanganate in the presence of the surfactant (CTAB), one obtains, after several low temperature stages and the higher temperature final firing Mn oxides of the types: LiMn2O4 or LiMnO3. KMnO4+CTAB Ultrasonicate Dark purple ppt filter CTA MnO4 LiOH Autoclave 95/105 °C 24-72 hrs Dry at 70 °C Firing 500-600 °C LiMnO4 or Li2MnO2 Activities carried out: Cathode Materials preparation and characterization
Activities carried out: Cathode Materials preparation and characterization Structural characterization Analysis of the X Ray pattern revealed that the sample named LiMnO-1 has the following formula: Li1.32Mn1.60O4
Structural characterization The SEM micrographs of the sample LiMnO-1 revealed round grains of homogeneous size (100 nm approx.). In some cases , though, some grains agglomeration can be observed. Activities carried out: Cathode Materials preparation and characterization
Electrochemical behaviour the charge-discharge capacity at different cycles number The electrochemical cell consisted of a cathode made of a paste of the LiMnO-1 powder with a 10% acetylene black, a Li anode and a liquid electrolyte (EC-DEC with LiPF6) supported on a plastic separator. It is evident the initial charge related to the formation of an irreversible surface layer. The specific capacity, as previewed, lowers wit the increasing of the cycling regime. Though the performance is not very satisfying, nonetheless the material proved to be electroactive. Activities carried out: Cathode Materials preparation and characterization
Activities ongoing : Cell Assembling(1)
A cathode paste is made from cathode powder, binder powder (10% PVDF), solvent, and additives (~5% acetylene black [AB], with some NMP) in a chemical vessel and pumped to the mixing machine.
The process: Mixing Machine
2. Coating machines spread the paste to a thickness of about 200 to 250 μm on both sides of the Al foil (about 20 μm thick, purchased in rolls). Drying reduces the thickness by 25 to 40%. The coated foil is calendared to make the thickness more uniform and then slit to the suitable width. Coating machines 3. Graphite paste is produced with a similar process as that for the cathode ones. Activities ongoing : Cell Assembling(2)
The anode, separator, and cathode layers are wound up and inserted into cylindrical cases.
Cells are filled with electrolyte.
Insulators, seals, valves, safety devices, etc. are attached.
Operation for step 4, 5, and 6 should be carried out in Glove box.
Source:Hohsen Corp. schematic illustration for the cell assembly process Activities ongoing : Cell Assembling(3)
Glove Box Glove box is a sealed container with controlled atmosphere , which will allow the opepration be carried out in the desired atmosphere. For a battery preparation , What atmosphere is needed? Oxygen concentration<1ppm humidity <1ppm Activities ongoing : Cell Assembling(4)
◆ In the first year of study, an intensive and thorough literature work has been concluded. Comparison of different type of lithium ion batteries was made. ◆ Based on such literature study, a suitable low cost, simple synthesis methods and lot cost, safe materials will be employed to obtain the Li x Mn y O z powders with controlled morphology, particle size, nanostructure and high purity which is essential for the success of this study. ◆ Synthesis and characterization of the first cathodes materials sample was made. ◆ Further synthesis and characterization of the cathodes materials and battery assembly work are ongoing in the lab. Conclusions
◆ Preparation and characterization of LixMnyOz , as well as Lithium Iron Phosphate (LiFePO4) material in cooperation with Henan University of Technology. ◆ Implementation of battery assembly. ◆ Characterization of assembled batteries. Future work