Cristelle HERRIOT Application Engineer ENTEGRIS TOWARD A BETTER CONTROLLED MANUFACTURING PROCESS

Transcription

1 Cristelle HERRIOT Application Engineer ENTEGRIS TOWARD A BETTER CONTROLLED MANUFACTURING PROCESS

2 STATE OF THE ART

3 What is a contamination Particular (solid) and molecular (ionic) Distinction between the harmful and acceptable contamination All contaminants don t need to be removed Battery recalls linked to defects due to process deviation or to contamination generated by the process or other factors Contamination Failure (accelerated ageing ) Safety issue In analogy with semi-conductor industry, contamination can be brought by Human Factor, Environment, Raw materials, Processes Source:

4 Nature of the contaminations found in the literature impacting the battery Metallic particles mostly linked to the process especially slurry preparation and welding Moisture in electrolyte leads to HF formation LiPF 6 hydrolysis LiPF 6 + H 2 O LiF + 2HF + POF 3 LiPF 6 unstable PF 6 - F - + PF 5 PF 5 + H 2 O 2 HF + POF 3

5 Nature of the contaminations found in the literature impacting the battery Metallic particles mostly linked to the process especially slurry preparation and welding Moisture in electrolyte leads to HF formation LiPF 6 hydrolysis LiPF 6 unstable Current collector corrosion, Material dissolution, Gas evolution Source: J. Vetter, P. Novák, M.R. Wagner and co., Ageing mechanisms in lithium-ion batteries, J. Power Sources, 147 (2005) p Other contaminants: Molecular such as organics (typically NMP) Particle such as inert (typically SiOx or mineral particles)

6 Human METHOD TO DETECT CONTAMINATION Air Process (equipment, surface) Products

7 Exploitation of SAFT quality system and analytical methods from Entegris Identification of possible contaminated area (Ishikawa diagram) FMEA analysis: depending on production parameters Identification of the most potential harmful contaminant Audit guideline : definition of sampling method on equipment, tools, products and measurement on environment and human factors Audit achievement: sampling and analysis Contaminated area and sources of contamination identified Contamination Solutions to be implemented in-line (tools or methods) No contamination No action

8 SAFT Li-ion cells manufacturing line Audit performed at SAFT and methods applied to CEA UPE membrane analysis Electrode moisture after each step Environment Particle and moisture Human Factor Methodology, moisture Air sampling Karl Fisher Sampling methods to capture particles OPC Process Raw materials Solvent and electrolyte particle counting analysis Sampling on equipment Powders, solvents, electrolytes, gases OPC *OPC Optical Particle Counter

9 Normalized Risk Priority Number (%) Failure Mode and Effect Analysis performed on 2 sites (production line at SAFT, pilot line at CEA) Main critical contaminants identified at the level Machine, Methods, Materials More contaminants found at electrode fabrication compared to cell assembly Example of FMEA

10 EXAMPLES ON RAW MATERIALS & ENVIRONMENT Optical Particle Counter for liquids (solvents) Filtration setup

11 Example of NMP used to prepare slurry for the cathode. Particle count increase due to transportation and contact with mixing vessel

12 Membrane filtration to retain particles in NMP After filtration at the point-of-use Filtration decreases particle size and efficiency is calculated

13 Normalized particle count (%) Normalized particle count (%) Example of H 2 O used to prepare the slurry for the anode with / without filtration. H 2 O d=0.5µm H 2 O d=1 µm Solvent transportation is the primary contamination source in H 2 O

14 Downstream Downstream Upstream Upstream Post-mortem analysis of the filter used to filtrate the solvents NMP membrane H 2 O membrane Fe-Cr Fe oxyde SiOx (Fe traces) SiOx

15 Batches of 50 battery cells (40 Ah) have been assembled with different configuration 1 batch without filtration 1 batch with filtration on NMP (+) 1 batch with filtration on H 2 O (-) 1 batch with filtration on both solvents Cell scrap rate decrease when using filtration of solvents

16 Objective: ISO Class 7 1 st solution: sleeve modification in dry room 2 nd solution: modification of the air filtration entrance Objective ISO 7 is reached: final results below 7 for 0.5 and 5 µm

17 We demonstrated that contamination during battery production plays a contribution to battery initial electrical characteristics. Filtration solution for the solvents is an example of improvement improving battery production yield. Environment with ISO Class dry room improvement better than 7 has been demonstrated. The impact of those combined parameters will need to be studied and statistical methods will have to be implemented over years to understand the correlation between the factors and battery performance.

18 OTHER CONTAMINATION CONTROL SOLUTIONS TO BE DEVELOPED Exploration of new contaminants during battery production dedicated to raw materials

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20 The ELIBAMA project is granted by the European Commission under the Nanosciences, nanotechnologies, materials & new production technologies (NMP) Theme of the 7th Framework Programme for Research and Technological Development.