Fundamental Approach to Electrode Fabrication and … · Fundamental Approach to Electrode...

BERKELEY LAB DOE AMR 2011

Fundamental Approach to Electrode Fabrication and Failure

Analysis

Vince BattagliaLBNL

May 11, 2011

This presentation does not contain any proprietary, confidential, or otherwise restricted information

es081_battaglia_2011_o


es081_battaglia_2011_o 2/20

• October 2008• September 2012• 65 % Complete

• Barriers addressed– A. Cost– C. Performance– E. Life

• Targets– 205 $/kWh– 207 Wh/l– 15 years

• Total project funding– DOE share = 100%– Contractor share = 0%

• Funding received in FY10• $865 k

• Funding for FY11• $865 k

Timeline

Budget

Barriers

Partners

Overview

PIs Companies

V. Srinivasan Conoco Phillips

B. Lucht Daikin, Japan

M. Doeff NEI

J. Cabana SWeNT

G. Ceder Nippon Denko

K. Zaghib HydroQuebec

A. Manthiram

A. Angell



Relevance: General

ObjectivesTo make “good” electrodes.

– What does this entail?• Correlate electrode performance with the fundamental

properties of its constituents.• Provide fundamental understanding of key electrode

processing steps.• Provide fundamental understanding of electrode failure, i.e. is

it a result of the electrode formulation/processing or of the active material properties?

• Test materials to evaluate their full potential.• Provide quality electrodes to other BATT researchers.



Relevance: 2010 to 11Objectives

Specific to 2010/11 –– Develop a sealed cell with a reference electrode that allows

long-term cycling outside of a glove box and does not require an additional separator. (Critical to understanding cycle life issues.)

– Understand the electrode performance of an off-stoichiometric material as compared to a carbon-coated material. (A material tested in the ABR Program but moved to the BATT Program for in-depth analysis.)

To meet OVT’s Targets of Cost, Performance, and Life it is essential that we have electrodes that exhibit

maximum energy density, adequate pulse-power capability, and long life.



Approach/Strategy

Powders

Physical CharacterizationBET, PSA, SEM, TEM

Industrial PartnersBATT PIs

Electrode CharacterizationSide rxns vs. Li, Rev. and Irrev. Capacity, Rate

Chemical CharacterizationDissolution

Cell CharacterizationSide Rxns in Full Cell, Cycling Ability, Impedance

Electrode FabricationTensile & Peel Strength, Viscosity, 4-pt. Probe

Understand need for specific binder& conductive additive properties.Evaluate physical effects ofprocessing steps.Correlate electrode performance to electrode processing, loadings, and particle size.

ModelingDiagnostics

Battaglia Group

Updated ManualsPublications

FundamentalUnderstanding of

Key Fabrication Steps


Performance Limitationsand Cycle Life

Correlations of ElectrodePerformance to

Physical Properties

Correlate to electrodeperformance

Determine species and mechanism

Identify sources of failure, sources of cross talk, and benign vs. detrimental reactions


Failure Modes



DOE Reportable Milestones2010 thru 2011

Distribute electrodes cycled to different cut-off voltages to BATT program members. (Apr. 10)

Report results of mechanical properties vs. cycling capability of NCM-PVdF-based cells. (Sep. 10)

Procure 20 g of high-quality LiNi1/2Mn3/2O4. (Jan. 11)

Supply laminates of LiNi1/2Mn3/2O4 that survive 100 cycles. (Apr. 11)

Report the solubility of Mn compounds. (Apr. 11) On schedule

Report side-reaction rates of NCM vs. Li and vs. Graphite. (Jul. 11)

Report the rate of side reaction of LiNi1/2Mn3/2O4 vs. Li. (Sep. 11)

Complete

Complete

Complete

On schedule

On schedule

On schedule

On schedule

Approach/Strategy



LNMO(NEI)/CGP-G8

Technical Accomplishments and Progress:1. Battery Fabrication Manual published online Dec. 17, 2010

Following the manual, a visiting researcher was able to achieve this level of performance in 4 months.

More on this system in the poster – es029_battaglia_2011_p

Y. Fu



Canada (2)

United States (66)

China (4)

Germany (2)

Greece (1)

India (3)

South Africa (1)

Spain (1)

Sweden (1)

Taiwan (1)Turkey (1)

Ukraine (1)

United Kingdom

(1)

France (1)

Technical Accomplishments and Progress:1. Battery Fabrication Manual published online Dec. 17, 2010

88 Downloads as of March 9, 2011- 14 Countries- 25 States in the U.S.

http://berc.lbl.gov/vbattaglia/cell-analysis-tools/

M. WangK. Striebel



MCMB18-20/NMC(Argonne)

1.621.631.641.651.661.671.681.69

1.7

140 160 180 200 220 240

Cycle number

Cap

acity

/ m

Ah

Discharge

Linear loss

Fractional loss

Technical Accomplishments and Progress:2. A tool for assessing capacity fade and resistance rise.

MCMB18-20/NMC(Argonne)

0

0.5

1

1.5

2

2.5

0 50 100 150 200 250

Cycle number

Cap

acity

/ m

Ah

0.84

0.88

0.92

0.96

1

1.04

Cou

lom

bic

Eff.

Charge

Discharge

CE

C/20

C/21C

Modeling Capacity Fade

<0.99953>

• Coulombic efficiency is fairly constant from 50 cycles onward.• Capacity fade begins at ~ 150 cycles.• Consider two models for capacity fade:

• Linear – Q = Qo – Qo(1-η)*(Ncycle – 150) where η = cycle efficiency• Fractional – Q = Qoη (Ncycle – 150)

• The 2 models are indistinguishable w/ η = 0.99953; under predicts by a factor of 1.7.• Only 40% of the side reaction is detrimental. Goal is 0.99996 efficient.

It is critical to understand these side reactions.

linear fit predicts 920 cycles

Y. Fulinear loss of(1-0.99974)



Technical Accomplishments and Progress:2. A tool for assessing capacity fade and resistance rise.

SNG - C/24 formation, C/10 cycling, 0 and 2% VC

0.0%

0.5%

1.0%

1.5%

2.0%

0 10 20 30 40Cycles

Frac

tiona

l Cap

acity

Shi

ft 0%VC2%VC)

SNG-C/150 formation, C/10 cycling, 0 and 2% VC

0.0%

0.5%

1.0%

1.5%

2.0%

0 10 20 30 40Cycles

Frac

tiona

l Cap

acity

Shi

ft

0%VC-22%VC-2

SNG capacity shift/rev cap (%)

0%

1%

2%

3%

4%

5%

6%

7%

0 5 10 15cycle number

cap

shift

Graphite vs Li-1Graphite vs Li-2Graphite vs NCAGraphite vs NCA, 2%VC

• No effect of vinylene carbonate (VC) or formation protocol on graphite side-reaction rates when cycled against Li.

• Coulombic inefficiency of graphite doubled when cycled against NCA, suggesting the presence of a high-voltage shuttle.

• VC appeared to deactivate the shuttle and thereby improve coulombic efficiency.

P. Ridgway

Side Reactions



C/10 Cycling Performance of a 3-Electrode Coin Cell

00.20.40.60.8

11.21.41.61.8

2

0 10 20 30 40 50 60 70 80 90 100Cycle

Rev

cap

(mA

h)

97.6

98

98.4

98.8

99.2

99.6

Effi

cien

cy (%

)

rev capefficiency

-Im(Z) vs. Re(Z)L3CPG8-3 ACI 3(FC)_03.mprL3CPG8-3 ACI 2(CE)_03.mprL3CPG8-3 ACI 1(WE)_03.mpr #

Re (Z) /Ohm .cm ²

2010-I

m(Z

)/O

hm

.cm

² 6

4

2

0anode

cathode

full cell

Two ~C/25 formation & 96 ~C/10 cycles

2.9

3.1

3.3

3.5

3.7

3.9

4.1

0 0.5 1 1.5 2Capacity (mAh)

Cat

hode

(V v

s Li

ref)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Ano

de (V

vs

Li re

f)

cathode voltage anode voltage

Technical Accomplishments and Progress:2. A new tool for assessing capacity fade and resistance rise.

We have developed a novel 3-electrode coin cell to simultaneously study long-term cycling effects and side reactions of both electrodes.

3-electrode Cell

We expect this cell to be very helpful in assessing cell failure!

P. Ridgway

Traditional New Coin Cell



Amorphous film is visible with HRTEM

Carbon film is visible with HRTEM

Technical Accomplishments and Progress:3. HQ’s LiFePO4 is as high rate as G. Ceder’s (MIT) with the addition of acetylene black.

Three LiFePO4 materials were evaluateda) Ceder’s off-stoichiometric, nano-material:

LiFe0.9P0.95O4-δb) LBNL’s stoichiometric, nano-material:

LiFePO4c) HQ’s carbon coated material:

LiFePO4 / C

LiFe0.9P0.95O4-δ LiFePO4 LiFePO4 / C

The MaterialsJ. ChongX. Song

The Ceder material was pre-evaluated in the ABR Program.

X-ray signatures are similar



Technical Accomplishments and Progress:3. HQ’s LiFePO4 is as high rate as Ceder’s with the addition of acetylene black.

Sample D10(µm)

D50(µm)

D90(µm)

BET(m2.g-1)

Eqv. Dia.(mm)

LiFe0.9P0.95O4 – δ 0.135 0.333 0.498 33.9551 0.049

Bare LiFePO4 0.219 0.402 0.651 47.3239 0.035

LiFePO4 / C 0.252 0.415 0.657 12.9335 0.12

0.01 0.1 10

2

4

6

8

10

12

LiFe0.9P0.95O4-δ

Particle diameter / µm

Volu

me

fract

ion

/ %

0.01 0.1 10

2

4

6

8

10

12

LiFePO4 / C


Volu

me

fract

ion

/ %

0.01 0.1 10

2

4

6

8

10

12

Bare LiFePO4


Volu

me

fract

ion

/ %

PSA detects secondary particles;

BET detects primary particles

Particle Size DistributionLiFe0.9P0.95O4-δ LiFePO4 LiFePO4 / C

J. ChongX. Song




Secondary particles Primary particles

SEM’s of Electrodes

The MIT and LBNL nano-particles agglomerate into secondary particles.

The HQ carbon-coated material segregates as primary particles.

J. ChongX. Song




• At 65% carbon, the electrode thickness does not affect the rate performance.• For the bare material and HQ material, 15% carbon additive is essentially all

that is needed.• With large amounts of conductive additive (65%) the rate is mostly limited by

solid-state diffusion of Li in FePO4. • Solid state diffusion is much slower for the bare material than either the MIT

LiPO-coated nanomaterial or the HQ carbon coated material.

C-rate CapabilityLiFe0.9P0.95O4-δ LiFePO4 LiFePO4 / C

J. Chong



65% Carbon Additive

With 65% carbon additive, the materials are rate limited by solid-state diffusion.

• The single-crystal HQ material has straight paths to the center of the particles.

• The coating on the MIT primary particles appears to facilitate diffusion to the center of the secondary-particle

• The LBNL material exhibits slower diffusion through the tortuous secondary particle.


J. Chong




Schematic of Solid State Diffusion Limitation

Work in progress.

Li+ Li+Li+

Fast but tortuous Slow but non-tortuousSlow and tortuous



Collaborations and Coordination with Other Institutions

Companies• Daikin, Japan will send their newest high-voltage electrolytes• Conoco Phillips provided baseline graphite and will send CGP-A12 shortly• NEI will provide a baseline LiNi1/2Mn3/2O4 spinel material for distribution to BATT PIs

through Y.-M. Chiang’s Group• Daikin, America will provide a baseline electrolyte for distribution to BATT PIs• HydroQuebec will provide LiNi1/2Mn3/2O4 spinel material

Principal Investigators• Receive powders from G. Ceder (MIT)• Make laminates for the V. Srinivasan Group (LBNL)• Make laminates for the J. Cabana Group (LBNL)• Provide TEM for the T. Richardson/G. Chen Groups (LBNL)• Provide electrodes to the B. Lucht Group (URI)• Make laminates with the M. Doeff Group (LBNL)• Receive LTO laminates and new LiNi1/2Mn3/2O4 materials from the K. Zaghib Group

(HQ)• Provide powders and electrolyte to A. Manthiram Group (UT)• Provide powders and electrolyte to J. Zhang Group (PNNL)• Provide powders and electrolyte to A. Angell Group



Proposed Future Work• Electrode design optimization• Electrode failure analysis

– LiNi0.5Mn1.5O4 has been identified as a focus area; we will use our approach to provide a fundamental understanding of its limitations.

• Optimize the design of high-energy electrodes, investigate the fabrication of high-loading electrodes that cycle well, and study the roles of inactive material chemistry and material physical structure

• Study the side reactions of all components, including the binder, conductive additive, and the current collector, and identify reaction products

• Investigate dissolution as a function of SOC, and determine its mechanism.• Compare the performance of active material from various sources, and

correlate performance to differences in physical properties such as crystallography, degree of metals disorder, and particle structure.

• Distribute powders, electrolytes, and laminates of baseline systems to BATT partners.

• Investigate the effect of Daikin high-voltage electrolyte on rate of side reactions, and identify reaction products with help from Diagnostics team.



SummaryWe are an integral part of a comprehensive team to

assess electrode materials from a fundamental perspective.

• We have developed a robust methodology for making electrodes that is proven to be transferable to BATT researchers and other institutions.

• Side reactions play a pivotal role in cell lifetime; we have developed a sealed 3-electrode cell that will allow us to rigorously study these effects and decouple the anode and the cathode for long-term studies.

• We conducted a rigorous assessment of two BATT LiFePO4-based materials and determined mechanisms for their inherent limitations.



Technical Back-Up Slides



Technical Accomplishments and Progress:2. A new tool for assessing capacity fade and resistance rise.

0

0.005

0.01

0.015

0.02

0.025

0.03

4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8

Upper Cut-off Voltage (V)

1/C

ell E

ffici

ency

- 1

0

0.02

0.04

0.06

0.08

0.1

0.12

4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8

Upper Cut-off Voltage (V)

Frac

tion

of b

atte

ry c

apac

ity p

asse

d af

ter 8

hrs

of s

ide

rxn

(%)

Rate of side reaction is a function of cell voltage.

Side Reaction and Cell Balancing

Demonstrates how much capacity a cell can be balanced during an 8 hr trickle charge.

Demonstrates that if Gr./NCM is held at 4.2 V, there is 10.7% capacity available for cell balancing without the need for electronics!

Y. Fu




Weight of active material vs. weight of conductive additive?

2rp 2rc

2rc

c

p

rr

=λ

( )2121 λλ

λ++

= bww

c

p

20675.08

33

c

p

c

pbρρ

πρρ

==0.01

0.1

1

10

100

0.1 1 10 100

rp/rcw

p/w

c

ρp/ρc = 4.5

Slope = 0.20675ρp/ρc

If λ = 0.4/0.05 and ρp/ρc = 3.6/(0.4*2) then wc/wp > 0.17

Gives an electrode of 14% carbon, 81% LiFePO4, and 5 % binder.

One can derive through geometric arguments the weight ratio of one material needed to cover another material:

where, and




• MIT material requires the least amount of carbon additive to attain high rates.• Ohmic and kinetic resistance not much improved beyond 15% carbon additive.

The addition of conductive carbon facilitates access to the particlesbeyond just an improvement in kinetics or ohmic resistance!

The Addition of Carbon Additive to the 3 Materials

LiFe0.9P0.95O4-δ LiFePO4 LiFePO4 / C

J. Chong

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