Graphite Powder Processing - DKG · 2014-12-02 · High Power between 10 and 30 µmHigh d 90 < 70...

$: Graphite Powder Processing - DKG · 2014-12-02 · High Power between 10 and 30 µmHigh d 90 < 70 µm Low amount of fine particle fraction Particle size distribution and shape 0 25$
Graphite Powder Processing

A Key Element for High Performance Lithium-Ion Batteries

Bernt Ketterer, Ulrich Bosch, Oswin Öttinger, DKG-AKK Herbsttagung, 7th November 2014

Page 2 For internal use only | SGL Group master 0214

Graphite Powder Processing for High Performance Lithium-Ion Batteries Outline

SGL Proprietary Information

1. Graphite Anode Materials: Position of SGL & Market Perspectives

2. Anode Materials for Lithium Batteries: Basic Requirements

3. Powder Design for High Performance Graphite Anodes, Influences of: • BET Surface Area • Particle Size • Particle Shape

4. Summary


LIB Anode Materials Overview Material Share – Status 2012

Source: SGL, Avicenne, Battery Market Development 2012-2025

- Artificial and natural graphite biggest share (total >90%)

- Next generation high capacity materials (silicon and tin based) enter the market

- Fast growing market for graphite anodes in 3C and electromobility

Total Volume in 2012: ~32000t



Graphite Anode Materials Joint Forces for Best Solutions

World Largest Synthetic Graphite Anode Production & Leading Edge Technology Know How

More than 10 Years Cooperation








4. Summary


electrons flow

Graphite-Anode

Al –

cu

rren

t co

llect

or C

u – cu

rrent co

llector Cathode

Charge Li+ ions flow

Li+ ions

electrons flow

Al –

cu

rren

t co

llect

or C

u – cu

rrent co

llector

Li+ ions flow

Cathode Graphite-Anode

sepa

rato

r

Discharge

Li+ ions

Lithium Ion Battery: Basic Working Principle


sepa

rato

r

Electrolyte

Electrolyte

Graphite Polymeric

Binder

Conductive additive

Cu-foil current collector


Li-Ion Battery - Graphite as Anode Material Solid Electrolyte Interface - SEI

Source: TEM: F. Orsini, L. Dupont, B. Beaudoin, S. Grugeon, J.-M. Tarascon, Int. J. Inorg. Mater. 2 (2000), 701 AND E. Peled, D. Golodnitsky and G. Ardel, J. Electrochem. Soc. 144 (1997), L208.

TEM of Solid Electrolyte Interphase Schematic drawing of the composition of the SEI

First Cycle: Carbon/graphite + Electrolyte Solid Electrolyte Interphase

Solid Electrolyte Interphase (SEI)

Carbon/ Graphite

Li2O

LiF

LiF

LiF

Li2O

Li2O

Li2O

Li2CO3

LiF

Li2O

Li2O

Li2CO3

Li2CO3

Electrolyte (LiPF

6 , Carbonates,etc.)

Polyolephines

Semicar bonates

Polyole phines

The SEI protects the graphite from solvent co-intercalation Graphite would not work without SEI


SEI formation consumes Lithium!


Key Parameters of Electrode Materials: Capacity and Efficiency

Capacity loss (1st Cycle Efficiency): How much lithium contributes to SEI-formation? Depending on:

• specific surface (e.g. BET)

• particle size and shape

Capacity: How much lithium is intercalated in graphite? Depending on:

•How many defects are in the graphite?

• Degree of graphitization

Surface –Electrolyte Interphase Layer (‚SEI‘ ): Passivating layer formed on the graphite particle surface

Li Graphite Particle


1µm


Specific Capacity (mAh/g)

Voltage Level

1st Cycle Efficiency

Electrode Loading (mAh/cm²)

% Inactive Material

Film Swelling

Material & Film Density (g/cm³)

Rate Capability (Temperature-Dependence)

Particle Size / BET

Purity

Cycle Stability

Graphite Anode Materials: Basic Requirements


Gravimetric Energy Density

Wh/kg Volumetric Energy Density

Wh/l

Safety

Directly Influenced by Graphite Particle

Properties

Lightweight Battery

Small Battery

Power Density W/kg or W/l

Battery Level Material Level

Acceleration







4. Summary


Lower BET Surface Area: Optimized Battery 1st Cycle Efficiency

Surface Area (m 2 /g) 0

89

90

91

92

93

94

95

96

Surface Area (m 2 /g)

Cou

lum

bic

Effic

ienc

y (%

) C

oulu

mbi

c Ef

ficie

ncy

(%)

1 2 3 4 5

A low BET surface is crucial for: • 1st cycle Efficiency (low Li losses) • Energy density • Safety • Cycle life • Binder demand …



Lower the BET Surface Area: Influence of the milling device

Milling type & milling & spheroidisation equipment configuration influence significantly the particle shape / BET and therefore also the battery performance

Additionally milling & rounding yield is the key element for commercial success

Different Milling Devices

BET

Surf

ace

(r

elat

ive

num

bers

) d50 = const.

Examples from Different Milling Devices



Lower the BET Surface Area: Influence of rounding and the coating

2 nm

Graphite

Carbon coating layer

10 µm 10 µm

Rounding Coating

Graphite powder Engineered anode material


Lower BET Suface


Quicker Charge/Discharge: Influence of the Particle Size

Li+

Li+

Graphite with medium

particle size

Graphite with very small

particle size

Li+

Li+

d50 between 10 and 30 µm d90< 70 µm Low amount of fine particle fraction

Particle size distribution and shape

0 25

75

125

175

225

275

325

375

Spec

ific

Cap

acit

y in

mA

h/g

High Energy

slow quick Log (Dis. - )/Charging Time

very small D 50 value ( i.e . 10 µ m)

Medium D 50 Value ( i.e . 20 µ m)

Smaller anode particle size distribution is beneficial for quicker LIB charging. However… Formation of higher surface area


High Power


Quicker Charge/Discharge: Influence of the Particle Shape

How fast is lithium intercalated in graphite? Depending on particle orientation in the electrode


Cu-current collector

x ‘Flaky’ Graphite Particles

Potato Shaped Graphite Particles

Li+

Li+

Flaky

Potato


High Film Density for Improved Energy Density: Influence of Particle Shape & Particle Size Distribution

„Potato shape“ particle generates higher film packing density at lower compaction pressures

Bimodal / “broader” particle size distribution can generate higher film

packing densities. However, BET need to be kept low, otherwise efficiency loss

Compaction Pressure

Elec

trod

e Fi

lm D

ensi

ty

high Low

high

“Potato”particle shape

“Flaky”particle shape

0,1 1 10 0,1 1 10

Elec

trod

e Fi

lm D

ensi

ty

Density + 20%


Particle Size Particle Size







4. Summary


Graphite Powder Processing for High Performance Lithium-Ion Batteries Key Elements - Summary

Energy Density

1st Cycle Efficiency

Quick Charge

Cycle Life

Particle Size

Particle Surface

(coating)

Particle Shape (BET)

Particle Size Distribution

Yield Costs



Important note: This presentation may contain forward-looking statements based on the information currently available to us and on our current projections and assumptions. By nature, forward-looking statements involve known and unknown risks and uncertainties, as a consequence of which actual developments and results can deviate significantly from these forward-looking statements. Forward-looking statements are not to be understood as guarantees. Rather, future developments and results depend on a number of factors; they entail various risks and unanticipated circumstances and are based on assumptions which may prove to be inaccurate. These risks and uncertainties include, for example, unforeseeable changes in political, economic, legal, and business conditions, particularly relating to our main customer industries, such as electric steel production, to the competitive environment, to interest rate and exchange rate fluctuations, to technological developments, and to other risks and unanticipated circumstances. Other risks that in our opinion may arise include price developments, unexpected developments connected with acquisitions and subsidiaries, and unforeseen risks associated with ongoing cost savings programs. SGL Group does not intend or assume any responsibility to revise or otherwise update these forward-looking statements.


Graphite Powder Processing - DKG · 2014-12-02 · High Power between 10 and 30 µmHigh d 90 < 70...

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Transcript of Graphite Powder Processing - DKG · 2014-12-02 · High Power between 10 and 30 µmHigh d 90 < 70...