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Process development and optimization for

Li-ion battery production

Mareike Wolter, Diana Leiva, Marco Fritsch, Stefan Börner

© Fraunhofer IKTS - 2 -

Fraunhofer IKTS in profile - Research fields

Structural ceramics Functional ceramics

© Fraunhofer IKTS - 3 -

Ceramic Expertise Battery Expertise

Battery research at Fraunhofer IKTS

Material

Technology

Electrode Battery Cell

Manufacturing

© Fraunhofer IKTS - 4 -

Process development and optimization for Li-ion battery

production

electrode

manufacturingslurry mixing,

coating, drying

+ -Li-Ion IKTS

raw

materialspowder

electrode foil

'.

slitting/ cutting

joint tabs,

terminalssealing

EoL conditioningformation

aging

EoL testing

cell assemblystacking

calendering

electrolyte

filling

© Fraunhofer IKTS - 5 -

Process development and optimization for Li-ion battery

production

� Optimum battery performance and

lifetime relies on optimized battery

production

� Process optimization is the main tool to

reach cost targets

© Fraunhofer IKTS - 6 -

© Coatema, Hirano

Electrode manufacturing

� State of the art coating technology developed for small

consumer cells

� Automotive application requires

4x lifetime

10x cycle number

20x larger electrode areas

� significant higher requirements on production processes

© Fraunhofer IKTS - 7 -

mixing

coating

calendering

slitting

stacking/ winding

connecting electrodes/

packaging

electrolyte filling/

sealing

form

ation / aging

clean / dry room

environment

battery performance /life

time

battery failures

� Relevance of process steps regarding battery quality

Process development and optimization for Li-ion battery

production

© Fraunhofer IKTS - 8 -

mixing

coating

calendering

slitting

stacking/ winding

connecting electrodes/

packaging

electrolyte filling/

sealing

form

ation / aging

clean / dry room

environment

battery performance /life

time

battery failures

� Relevance of process steps regarding battery quality

Process development and optimization for Li-ion battery

production

© Fraunhofer IKTS - 9 -

Understanding process parameters I

Electrode geometry

� Significant influence on energy and power

characteristics

� Formation of electrically conductive network

� crucial for thicker high

ED-electrodes and high C-rates

0

1

2

3

0 2 4 6 8

Capacity / mAh/cm²

Current density / mA/cm²

Capacity NCA/C cells

� typical high

power/high energy

characteristic

discharge

chargeVoltage

dropthick electrode

thin electrode

© Fraunhofer IKTS - 10 -

110

120

130

140

0 1 2 3Capacity / mAh/g

Current density / mA/cm²

68 N/mm88 N/mm218 N/mm667 N/mm

Understanding process parameters II

Rate Rate Rate Rate capabilitycapabilitycapabilitycapability ofofofof LFP/C LFP/C LFP/C LFP/C cellscellscellscells

� Calender force is used to adjust

electrode porosity

� Porosity has significant influence on rate

capability

� Calendering enhances

electrical inter particle and particle

to current collector resistance

© Fraunhofer IKTS - 11 -

Understanding process parameters III

0%

20%

40%

60%

80%

100%

120%

0 50 100 150 200

Capacity retention / %

Cycle

68 N/mm 218 N/mm

667 N/mm dR 68

dR 218 dR 667

AgingAgingAgingAging ofofofof LFP/C LFP/C LFP/C LFP/C cellscellscellscells

� Calender force is used to adjust

electrode porosity

� Porosity has significant influence on rate

capability

� Calendering enhances

electrical inter particle and particle

to current collector resistance

� Higher adhesion & cohesion of active

layer to electrode

� Optimized capacity retention

2C-Cycle test at 60°C

© Fraunhofer IKTS - 12 -

mixing

coating

calendering

slitting

stacking/ winding

connecting electrodes/

packaging

electrolyte filling/

sealing

form

ation / aging

clean / dry room

environment

battery performance /life

time

battery failures

equipment investments

operating costs

� Relevance of process steps regarding battery quality and costs

Process development and optimization for Li-ion battery

production

© Fraunhofer IKTS - 13 -

mixing

coating

calendering

slitting

stacking/ winding

connecting electrodes/

packaging

electrolyte filling/

sealing

form

ation / aging

clean / dry room

environment

battery performance /life

time

battery failures

equipment investments

operating costs

� Relevance of process steps regarding battery quality and costs

Process development and optimization for Li-ion battery

production

© Fraunhofer IKTS - 14 -

Investigating process optimization I

Drum mill Dispenser

Planetary mixer

Intensive mixer

Mixing at lab scale

� Material and recipe development

Mixing at pilot line scale

� Investigation of mixing parameters and technologies

� Optimization mixing time

© Fraunhofer IKTS - 15 -

Investigating process optimization II

Coating at pilot line scale

� Process stability, defects

Coating at lab scale

� Effect of slurry properties regarding coating quality

� Development of coating technologies

Doctor blade

Slot die

© Fraunhofer IKTS - 16 -

Summary

� IKTS is working along the entire process chain of LIB electrode manufacture and

characterization

� Process development and optimization for Li-ion battery production results in a

series of complex processes with many parameters and diverse optimization goals

� DoE

� Depending on development goal work has to be done on lab or pilot line scale

� Never forget the strong interaction between technology and product properties!

Organized by Hosted by In collaboration with Supported by

Thank you for your attention!

Special thanks to: � the European Regional Development

Fund (ERDF) and the Free State of

Saxony for funding of this work

� our Co-workers in the project LiFab