NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Impact of ALD Coating on 

Li/Mn-rich Cathode Materials

Shriram Santhanagopalan

Center for Transportation Technologies and Systems 

National Renewable Energy Laboratory

May 14, 2013

NREL/PR-5400-58277 Project ID #ES196

This presentation does not contain any proprietary, confidential, or otherwise restricted information.
2

Overview

Project Start Date: 06/01/2012

Project End Date: 05/31/2013

Percent Complete: 70 % 

• Barriers addressed

Capacity fade during cycling of Mnrich cathode materials at high 

temperatures

Scale-up issues associated with 

Atomic Layer Deposition

Total Project Funding: $110k

DOE Share: $110k

Contractor Share: N/A 

Funding Received in FY12: $110k

Funding for FY13: None

Timeline

Budget

Barriers

• Mohamed Alamgir (LGCPI)

• Karen Buechler, David King

ALD NanoSolutions, Broomfield CO

Partners
3

Relevance

• The ABR program has identified manganese rich cathode as an attractive candidate 

for vehicle batteries. This material offers several benefits including a wider 

operating window and higher energy density.

• One of the major limitations for this material pertains to cycle life.

• LGCPI & NREL have previously conducted a scoping study on coating Mn-rich 

cathodes with oxides of alumina, which provided useful indicators to improving 

cell performance:

• ALD coating mildly reduced power-capability

• Improvement in cycling due to coating is significant when applied to Mn-rich cathode

• Anode coating did not bring about much of an improvement

• With this background, LGCPI & NREL jointly proposed to assess the scalability of 

the ALD coating technique on Mn-rich cathode material as well as sheets of 

electrodes.

• The objectives of this effort are:

• To re-affirm the benefit of coating of LG Chem Power Inc. (LGCPI) cathodes 

with ALD to improve their rate capability, life, and abuse tolerance of 

electrodes, at a pilot-scale. 

• To assess the feasibility of coating electrodes using the ALD technique.
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Milestones

Month 

/ Year

Milestone or 

Go/No-Go Decision

Description Status

M1/Y1

(June

2012)

Receive baseline

active material

• NREL received two different batches of baseline 

cathode material (powder) and sheet electrodes for 

ALD coating.

Complete

M6/Y1

(Dec. 

2012)

NREL to ALD coat 

powder samples with 

help from 

subcontractor

• NREL and ALD Nanosolutions built a sub-contract in 

place to coat cathode powders and electrodes 

• Two baseline samples were coated to produce 4 

different batches of coated material

Complete

M6/Y1

(Dec. 

2012)

NREL to fabricate 

cells from baseline 

and coated samples 

for screening

• Coin cells were fabricated using both the baseline and 

coated materials; results discussed in slides below 

were used to down-select coating conditions for the 

second round

Complete

M9/Y1

(Mar. 

2013)

NREL to ALD coat

electrode samples 

with help from 

subcontractor 

• ALD Nanosolutions modified coating reactors to 

include sheet samples

• Electrodes for large format (5” x 5”) pouch cells were 

coated

Complete

M12/Y1

(June 

2013)

LGCPI to evaluate 

performance of 

coated powders and 

electrodes

• LGCPI will fabricate pouch format cells to evaluate 

improvements in cycling performance against the 

baseline cathodes

In Progress
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Approach/Strategy

• LGCPI and NREL will build upon the success of the lab-scale work to 

demonstrate the benefits of the atomic layer deposition (ALD) technique to 

evaluate the scalability of the ALD coating process, and the benefits of ALD 

coatings for long term cycling and calendar life. 

• As part of the scalability assessment, direct coating of electrode sheets will be 

implemented; and the results compared to coating active material powders to 

fabricate electrode sheets in a subsequent step.

• To accomplish these steps, NREL will obtain bulk quantities of manganese-rich 

cathode powder and electrode sheets and coat the samples with help from a 

subcontractor (ALD Nanosolutions).

• The coating parameters will be optimized using screening tests carried out at 

NREL which include fabrication of coin cells from those samples.

• The powders and electrodes coated under revised conditions will be evaluated 

by LGCPI in large format pouch cells.
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Particle ALDTM: Basics of Atomic Layer Deposition

Unrivaled Particle Encapsulation

Competing coating technologies cannot 

produce the precision or quality of films 

that ALD can

ALD

Sol-Gel ALD well established CVD • Common in semiconductor industry

• Various applications for coating 3D objects

• Commercial reactors available

How to coat large batches of individual particles?

 Fluidized Bed Reactor (FBR)

• Gas flow fluidizes bed of particles

• Excellent mixing and heat transfer

• High surface area particles – coated conformally

• Industrially scalable technology

• ALD is sequential self limiting gas phase surface reactions. 

• Film thickness is controlled by the number of cycles. 

Atomic Layer Deposition (ALD)

A)

B)

A

B

Semi-continuous Particle ALD

system for coating battery materials

Schematics Credit: David King, ALD Nanosolutions
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Chemical Efficiency of a typical ALD FBR Process: 

Batch reactors use in-situ process monitoring with a 

Residual Gas Analyzer. The calibration curve shown 

above is used to assess efficiency of the-coating process

CH4 TMA

H2O

Sharp breakthrough

indicates high precursor

efficiency

Start

TMA

Dose

Start

H2O

Dose

Time

Intensity

Gas 

Flow The existing ALD FBR reactor can process up to 

8L of powder per batch

ALD NanoSolutions has the capability to process multiple batch size of powders

in three separate reactors which scale the Particle ALDTM coating from 10s of

grams to 10s of kg batches.

Particle ALDTM at ALD NanoSolutions

Process Steps:

1) Load bed of powders into Fluidized Bed Reactor (FBR)

2) Fluidize powders at coating temperature and pressure

3) Sequentially introduce ALD precursors A-purge-B-purge

4) Repeat 3 for desired number of cycles

Two baseline samples were coated to 

produce 4 different batches of coated 

active material.

Figures Credit: Marcus Groner, ALD Nanosolutions
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In the FY12 phase of the work 

with ALD NanoSolutions, NREL 

sub-contracted the installation of 

an electrode-rack to facilitate this 

reactor modification process.

An Electrode Holder for up-to 25 

electrodes of 6” x 6” size was 

devised for ALD coating sheet 

electrodes directly.

In addition to a small volume traditional flats ALD reactor and developing roll to roll ALD

coating, ALD NanoSolutions can install a holder for carrying out ALD onto a large number

of flats into the large volume ALD particle reactors. 

Electrode Coating at ALD NanoSolutions

Process Steps: 

1) Load Reactor with Electrodes

2) Bring reactor to coating temperature and pressure

3) Sequentially introduce ALD precursors A-purge-B-purge

4) Repeat 3 for desired number of cycles

Electrodes of 6” x 6” size will be coated directly using the holder build under NREL 

subcontract. Coating of Mn-rich NMC material underway.

Sheet samples of the Mn-rich cathode 

were coated using the modified 

reactors for fabrication and evaluation 

of large format pouch cells at LGCPI .

Figures Credit: Marcus Groner, ALD Nanosolutions
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Initial Results

SEM Images:

• The coatings on both types of particles 

show good uniformity.

• The alumina on LGC-HM02 tends to 

flake off readily (perhaps due to a 

different surface treatment on the 

baseline particles).

• No performance issues were observed 

due to the flakes, indicating that this is 

essentially a processing difficulty.

• Tailoring the surface-properties of the 

coatings to match those of the baseline 

material will help overcome such issues.

Sample - 1 (Baseline)

Sample - 2 (Baseline)

Sample - 1 (Coated)

Sample - 2 (Coated)

Weight percentages of Al2O3 coating

Chemical Stability:

• Check for chemical stability by 

storing the ALD coated samples in 

the electrolyte at 60oC did not show 

any abnormal gassing.

SEM Images Credit: Bobby To, NREL
10

Cell Evaluation

• During the initial evaluation, the coated sample showed almost no degradation after 50 100% 

DOD cycles between 4.4 and 2.75 V, whereas the baseline sample showed a decline in capacity.

• Some rate-limitations were observed at higher C-rates; an increase in the impedance was also 

noticeable.

• These issues are addressed in the subsequent coating trials by selecting the coating parameters 

to match target performance.

• There were no noticeable variability in coating the different batches indicating no limitations in 

scaling from lab-scale to the pilot scale.

10

Figures Credit: Mohamed Alamgir, LGCPI
11

Collaboration and Coordination with Other Institutions

• NREL and LGCPI have collaborated over several years in 

building Atomic Layer Deposition as a viable technique to 

improve the safety and cycling performance of lithium 

battery materials.

• This project actively leverages prior work by the two 

teams to address a performance limitation that will 

enable use of the manganese-rich material for use in 

automotive batteries.

• ALD Nanosolutions is a pioneer in developing the atomic 

layer deposition process and has rapidly transitioned labscale results to the industry in multiple disciplines.

• The Energy Storage group at NREL also has an ongoing 

collaboration with the University of Colorado at Boulder 

in screening the coating and test conditions. 

• Initial phase of this work was guided by findings by the 

US-Drive team that identified the need to resolve the 

cycling issues at high temperatures. The US-Drive Team 

provides periodic feedback during review meetings.
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Proposed Future Work

• This was a short-term fast-track project (total duration: 1 year)

• For the remainder of the performance period, the team will continue ongoing efforts in the following areas:

i) Evaluating coating of powders versus coating of electrodes

ii) Testing of large format cells fabricated using the ALD-coated electrodes

• The key milestone will focus on delivering cell-level test results from LGCPI

Future work Pending Support:

• Fine-tuning ALD attributes such as material composition and conductivity 

across the coating, as well as correlating these target properties with the 

deposition conditions will provide better control over the process. 

• Future support will help identify the process-knobs to build functional 

coatings at the production scale.

• A semi-continuous production option has been validated at ALD 

Nanosolutions for large-scale manufacturing; future support will help 

transition this effort into a continuous, in-line coating step integrated with 

the cell-fabrication process.
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Summary

• The FY12 studies show that the Atomic Layer Deposition technique is quite 

scalable with the cathode powders. A semi-continuous production option has 

also been validated for large-scale manufacturing and will facilitate industry 

adoption.

• Pilot-scale ALD coating of Mn-rich cathode powders and electrode sheets were 

successfully demonstrated.

• Initial evaluation results indicate that good cycling performance over the baseline 

material.

• Large-format cell testing is currently underway.

• The unique talent at ALD Nanosolutions, expert guidance from LGCPI and insight 

from University of Colorado at Boulder, have come together to help NREL deliver 

a reasonable solution on this fast-paced project.
Reviewer-Only Slides

(Note: please include this “separator” slide 

between those to be presented and the 

“Reviewer-Only” slides. These slides will be 

removed from the presentation file and the 

DVD and Web PDF files.)
15

Responses to Previous Year Reviewers’ Comments

If yours is an on-going project that was reviewed last year, 

address 1-3 significant questions/ criticisms/recommendations 

from the previous year’s reviewers’ comments, available at: 

http://www1.eere.energy.gov/vehiclesandfuels/resources/vt_m

erit_review_12.html. Last year’s presentations can be found at: 

http://www1.eere.energy.gov/vehiclesandfuels/resources/proc

eedings/2012_merit_review.html. 

This start date for this project was June 2012 and so we did not have any 

comments from reviewers in the previous year.
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Publications and Presentations

• Robert Tenent, USDRIVE Electrochemical Tech Team Meeting at ANL - 24 January 

2013.

• Shriram Santhanagopalan, Mohamed Alamgir, Karen Buechler and David King, 

Milestone Report titled Evaluate ALD Coatings of LGCPI Cathode Materials and 

Electrodes, Submitted October 2012.
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Critical Assumptions and Issues

• This project was scoped out based-on some initial laboratory 

scale data on performance improvements from atomic layer 

deposition over cathode powders.

• The team assumes that the coating parameters optimized for 

the powders can be used for the sheet coating process with 

minor modifications.

• Uniformity of the large batch of coatings has been 

characterized at the material level only based on limited 

samples (e.g., using SEM or flue-gas analyses). Initial results 

from large-format cell testing indicate no limitations; but 

variations from one batch to another have not been 

characterized under the current effort.

• The coating process is fine-tuned ad hoc for each run; this 

process must be standardized.