Review Summary Cla Clare Grey (P (PI) I) Rhodri i Je Jervi - - PowerPoint PPT Presentation

Degradation 12-Month Review Summary

Cla Clare Grey (P (PI) I) Rhodri i Je Jervi vis (P (PL) L)

• Recap of the Proje

ject

• Cycli

ling and Materials

• Scie

ientific ic Hig ighlights

• Year Two Pla

lans

Ov Over erview view

De Degrada adation tion

Suite of characterisation techniques to study battery degradation across multiple time and length scales Connect degradation processes to electrochemical signatures Learn via AI methods Integrate into BMS systems Connect to modelling activities

The T he Team eam

The o he over erar arching hing goals of goals of this pr this prog

• gramme

amme ar are e to: to:

• Identify stress-induced degradation processes
• Study synergistic effects in full cells
• Obtain correlative signatures for degradation
• Determine how cycling programs and materials solutions,

mitigate degradation

• Feedback fundamental understanding and provide insights into

how they can be improved.

• Provide insight into and help provide mitigation strategies for issues

and challenges being identified across the UK by various partners

Str Structur ucture e of

• f the Pr

the Project

• ject

WP1: Chemical Degradation (Clare Grey) WP2: Materials Degradation (Paul Shearing) WP3: Electrochemical Degradation (Ulrich Stimming) WP4: Materials Design & Supply (Serena Corr) Project Leader: Rhod Jervis

Cell Cycling/Materials

Ma Materia terials: Ov ls: Over erall S all Str trate tegy

Overview - Degradation Fast Start Page 8

• Year 1: 811 + graphite
• Year 2 and Beyond: Coated 811 and Si/SiO

Strategy

• 1. Purchase materials from recognized suppliers world wide
• Targray pristine material, coated electrodes (by ANL initially, then WMG)
• NEI – pristine material and coated electrodes
• BTR – pristine materials: graphites and coated 811
• Small scale testing across the consortium
• Identified challenge re. moisture sensitivity very early on – cannot scale-

up uncoated materials outside dry room

• Use of dry room in Cambridge
• Developed protocols for optimal full scale electrode construction at small

scale

• Larger scale electrode fabrication in Warwick
• Electrode fabrication in QinetiQ – this week !
• 2. Synthesize materials in-house (WP4) for bespoke experiments, coatings and

eventually scale-up

Rob Weatherup, Chris Sole (MAN/Diamond)

• O1s/C1s NAP XPS => suggest

rapid growth of LiOH & slower conversion to Li2CO3

3-electrode cells allow separation of anode and cathode polarisation

Benchmarking and Cell Development

Multiple scales of cells are needed: bespoke in situ cells with in house processing, stable performance from commercial materials, larger scale processing for post-mortem analysis

Page 9

Improved Formulations and processing lead to stable cycling performance Commercially sourced electrodes and large scale electrode coating

50 100 150 200 250 300 0.00 0.02 0.04 0.06 0.08

c (emu Oe-1 mol-1) T(K) ZFC FC Field = 100 Oe Li NMC 811

10

50 100 150 200 250 300 0.00 0.04 0.08 0.12

c (emu Oe-1 mol-1) T(K) ZFC FC Field = 100 Oe Li NMC 811_v2

50 100 150 200 250 300 0.0 0.1 0.2 0.3

c (emu Oe-1 mol-1) T(K) ZFC FC Field = 100 Oe Li NMC 811_v3

Targray, ANL Targray, WMG LiFun

Results (1) – dc magnetometry on 3 separate batches of pristine Li NMC 811

Susce Susceptibili ptibility ty Measur Measurement ements: s: A A Simpl Simple e Metho Method d for

• r

Scr Scree eening ning (Bulk) V (Bulk) Var aria iation tions s in Samples in Samples

Tirr= 122 K Tirr= 148 K Tcusp = Tirr= 8 K

• cluster glass
• cluster glass
• N. Chernova, M. S. Whittingham et al.

spin glass, Difference in ZFC and FC is measure

• f Ni occupancy in Li layers

Scie ientific Hig ighlights

A Summary of Key Year 1 Achievements

Page 12

• Materials: secured a supply chain, synthesised high

performance materials, scaled up, understanding processing, consistency

• Method development: refined in situ and operando

techniques, predictive machine learning algorithms, use of large scale facilities

• Advances in mechanistic understanding: Li mobility, gas

evolution, spectroscopic understanding metal dissolution, EPR of radicals

Li i Mobilit ity, , Raman

Chemical Information

In In-situ situ 7Li Li so solid lid-st state te NMR NMR: : Iden Identifies tifies Op Optimu timum m Wind indow with w with Highe Highest st Li Li-ion ion Con Condu duct ctivity ivity

Page 14

Li in NMC811 Li metal Li in the electrolyte Room temperature 55 C Room temperature

In Situ Raman spectr In Situ Raman spectroscop

• scopy can pr

y can probe

• be

chemical c hemical changes dur hanges during c ing cycling ling

Page 15

Li-Ion (pouch) cell embedded fibre-optics

Goal: Study of degradation processes in Lithium Ion Batteries (LIBs) using in-situ and in-operando Raman spectroscopy

Raman

Operando Raman – Cambridge Kerr Gated Raman – Liverpool New cell designs Interpretation of data –Liverpool and Cambridge

Gas formation, , AI I EIS IS

Electrochemical Observations

Detect Detecting ing Volume

• lume Changes

Changes on Cy

• n Cycling

ling via via Pr Pressur essure e Measur Measurements ements: : NMC811 NMC811 vs.

• vs. Li cells

Li cells

Page 17

• Fast cycling at C/2
• Cyclic volumetric changes due to

lithium plating/stripping

• Overall changes due to electrolyte

decomposition and gas evolution

• => extremely sensitive set-up

NMC 811 electrolyte Li

*corrected for temperature fluctuations

Niamh Ryall, Nuria Garcia Araez (Sot)

Gas Gas evolution fr

• lution from
• m NMC811

NMC811 vs.

• vs. graphite

phite cells cells

Page 18

• Three electrode cell with a reference

electrode

• ca. 3 mmol of gas evolved per mole of Li+

inserted on graphite in the first cycle due to SEI formation on graphite

• Gases consumed on rest – reaction with

cathode?

NMC 811 electrolyte Graphite Li0.5FePO4

*: corrected from temperature fluctuations

Niamh Ryall, Nuria Garcia Araez (Sot)

Can we use machine learning to detect degradation with EIS?

Page 19

• Experimental EIS spectra do not perfectly fit the

classic capacitor-resistor model. We can fit it to more complex equivalent circuits, but the fit can be ill-posed

• However, the spectrum changes with cycle

number, thus it is an indicator of degradation, but why and how?

• Can we use machine learning to detect

persistent but subtle features in the EIS that correlate with degradation?

Alpha Lee, Yunwei Zhang (Cam), Qiaochu Tang, Ulrich Stimming (New)

AI×EIS: Subtle but persistent correlation between impedance and cycle number at the “magic frequency”

Page 20

One “magic frequency” in the imaginary part of EIS was identified as the key predictor of cycle number. The bode plots of Im[Z] during cycling

Alpha Lee, Yunwei Zhang (Cam), Qiaochu Tang, Ulrich Stimming (New)

Mic icroscopy and Cry rystallography

Morphological Degradation

Post

• st-mor

mortem tem anal analysis r ysis reveals eals subst substantial antial par partic ticle f le fractu acturing ring

Page 22

C/20 cycles

Post-mortem analysis: EIS, XRD, SEM/EDX and ssNMR (K Marker) on cathode and anode, solution NMR on cycled electrolyte (J Allen, C O’Keefe) C/2 cycling ~ 14.3 % capacity loss

1 μm 1 μm Pristine NMC (by WMG Warwick) After 201 cycles Ref 1

Ryu, H.-H. et al. Sun, Y.-K. Chem. Mater. 2018, 30, 1155- 1163.

How is particle cracking affected by voltage window limits? holding at specific SOCs? shapes and sizes of particles?

Chao Xu, Katharina Marker (Cam)

Anisha Patel, Mel Loveridge (WMG) Page 23

Imaging the cross sectioned coin cell

Page 24 Anisha Patel, Mel Loveridge (WMG)

Team: Cate, Jedrzej, Georgina and Amogh (Cam) Page 25

NMC MC 811: r 811: reduc educing ing par partic ticle siz le size e for

• r in

in- an and d ex-situ situ TE TEM M an anal alysis ysis

Sub-μm particle size and high precision printing are essential for in situ electron microscopy

(a) Ball milling in a planetary mill – 60 min, 350 rpm Efficient fragmentation of secondary particles, crystallography and composition are preserved (b) Aerosol printing Mass transfer to substrate, compatible with TEM e-chip prep Targray secondary particles are too large for TEM work so: Standard electrodes can be studied with SEM and FIB

Pin Pin Li metal PEEK housing

Radiation

Potentiostat terminal Potentiostat terminal

Separator Electrode Current Collector

Bespoke Cell Housing In-situ and operando imaging Electrochemical cell

Operando XRD CT Technique Development

Tom Heenan, Chun Tan, Andy Leach, Rhodri Jervis, Paul Shearing (UCL), ID15 ESRF

Radiation

Potentiostat terminal Potentiostat terminal

1st projection … nth projection Reconstruction

Normalised intensity

FOV 400 µm x 400 µm 1 µm resolution Li-ion electrode particles (NMC)

1 µm voxel length 400 µm FOV

Tom Heenan, Chun Tan, Andy Leach, Rhodri Jervis, Paul Shearing (UCL), ID15 ESRF

Operando XRD CT allows Sub-particle Spatially Resolved XRD

1 2 3 4 5 6 0.9998 0.9999 1.0000 1.0001 1.0002 1.0003 1.0004 1.0005

Lp/Lpmean Depth Within Particle (mm) Uncycled

a lattice p. map Single particle

• Dist. Map

Sub-particle lp. mapping

• Distance map approach to plot radial distance

from centre of particle

• Pixel lattice parameter / mean particle

lattice parameter plot vs depth within particle (surface to core)

XRDCT – Sub-particle analysis

Sohrab Daemi, Tom Heenan, Chun Tan, Andy Leach, Rhodri Jervis, Paul Shearing (UCL), ID15 ESRF

Phase pure NMC, , Bespoke Materials, , Coatin ings

Materials Synthesis and Supply

Results: NMC-811 synthesis

Page 30

Intensity (a. u.) 2 (degree) ICDD PDF 56-0147 Furnace 450-18h Microwave 850-1h Furnace 450-18h

10 20 30 40 50 60 70 80 90

Sol-gel precursor Resulting NMC-811 XRD of sol-gel precursor and NMC-811

XRD indicates reduced Ni/Li cation site mixing in temperature regime 750-850°C Electrochemical testing reveal materials display similar performance to initial benchmarking ANL electrodes

First five charge/discharge cycles for microwave NMC-811 (C/10; up to 4.2 V)

Morphology control via long-chain alkyl surfactant addition

Intensity (a. u.) (a) Microwave 850-2h (b) Microwave 850-2h ICDD PDF 56-0147 (c) Microwave 850-2h

10 20 30 40 50 60 70 80

2 (degree)

Preferred orientation (I(003)/I(104) peak intensities)? Increasing surfactant concentration Increasing particle size and size heterogeneity

Dr Naresh Gollapally, PhD student Beth Johnston, Prof Serena Corr University of Sheffield

Increasing surfactant concentration

Wha hat t role do

• le do pr

prot

• tec

ectiv tive e (par (partic ticle) le) co coating tings s play play?

Page 31

• Novel routes to coatings involving new precursors (e.g.,

Al(OiPr)3)

• Synthesis of [(tBuO)2Al(μ-OH)]3 and use as a precursor

for coating synthesis

• Preliminary SEM and EDX results
• Very strong coating agent and tendency to

aggregation (type 2)

• Al(OiPr)3) thicker coating (type 1)– too thick coating

reduces particle contact and reduces capacity.

Victor Riesgo Gonzalez, Dominic Wright, Cambridge

1 Vs. 2 Conformal coating – prevent metal dissolution?

• protect surface from electrolyte “attack”
• vs. patchy cover – scavenge electrolyte decomposition products?

synthesise in house coatings and test commercial samples

Strategy:

Al2O3 /NMC Pristine NMC Al(OiPr)3) [(tBuO)2Al(μ-OH)]3

Year Two Focus

Year 2 Plans

Page 33

• Correlative understanding of degradation mechanisms from operando

and in situ experiments – technique development and significant initial experiments have already taken place on XAS, NMR, XRD, XPS, X-ray CT, XRD CT, Raman. Results from these experiments will be processed and inform mechanistic understanding

• Full cell testing as a priority
• Key parameters from initial degradation experiments to be fed into
• MSM. Discussions already under way as to the required

information/format of information

• More ‘top down’ input from industry on key questions or challenges

regarding degradation to investigate specific problems

Year 2 Plans

Page 34

• Iterative post mortem analysis to run along side operando

fundamental understanding, at a ‘prototype’ cell level (WMG/QinetiQ)

• Understanding how environmental conditions can influence physico-

chemical stability of 811

• Commercial 18650/21700 cells (pre-formed) to be added to a second

layer of post mortem analysis to understand what degradation mechanisms are key for industrially relevant ‘large scale’ cells (and which are not)

• Scale up and coated materials from WP4