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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

-Huge 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:

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

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

Patent Filing date Subject Component Method Characteristics of the materials

WO 2007/048142 From USA

2006 LITHIUM ION BATTERIES

anode :Li4Ti5O12 Nano-

crystallineCathode: LiMn2O4

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 LiMnO2Cathode: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.

World state of art about techniques used for cathodes materials synthesis

Technique proposed for this study is : hydrothermal technique

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 ofNanostructured oxides: small particle size or porous particles - decrease the oxides low electronic conductivitythin and homogeneous carbon layer formation on the grain surface during synthesis

Organization of this study

Component study

Cell assembly

Moduleproduction

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 °CFiring 500-600 °C

LiMnO4 or Li2MnO2

Activities carried out:Cathode Materials preparation and characterization

Activities carried out:Cathode Materials preparation and characterization

Structural characterizationAnalysis of the X Ray pattern revealed that the sample named LiMnO-1 has the following formula: Li1.32Mn1.60O4

Position [?2Theta]

20 30 40 50 60 70

Counts

0

100

400

LiMnO-1.CAF

Residue + Peak List

Accepted Patterns

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 behaviourthe 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)

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)

4. The anode, separator, and cathode layers are wound up and inserted into cylindrical cases.

5. Cells are filled with electrolyte.

6. 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 LixMnyOz 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

Thank you for your attention !