A pragmatic perspective on lithium ion batteries

A Pragmatic Perspective on Lithium Ion Batteries (LIBs)從實用的觀點評估鋰電池研究近期的契機

Bing HsiehNovember, 2015

$100B energy storage industry• Key Players: Japan, China, Korea, and US

Does Taiwan want to become a “key” player?

•In 2014, global lithium battery anode materials output totaled around 70,000 tons, concentrated in China and Japan, which together constituted over 95% of global anode materials sales volume.

•Global anode materials industry is highly concentrated, with major manufacturers including Hitachi Chemical, JFE Chemical, Mitsubishi Chemical, BTR, and Ningbo Shanshan, which held a combined market share of over 80% in 2014.

- Hitachi & Ningbo Shanshan: artificial graphite- BTR & Mitsubishi : natural graphite- JFE Chemical & Ningbo Shanshan in MCMB

(MesoCarbon MicroBeads)

Startups in the Bay AreaFounder University Focus

Amprius Yi Cui Stanford Si Anode

Imprint Energy James Evans UC Berkeley ZincPoly

Seeo (acquiredBy Bosch 博世 )

Nitash Balsara UC Berkeley Polymer Electrolytes

BlueCurrent Nitash Balsara UC Berkeley Oligomer Electrolytes

Saktis3 Ann Marie Sastry U Michigan Solid State LIBs

Cambrios Angela Belcher MIT Ag NanowiresTransparent conductor

C3Nano Zhenan Bao Stanford CNT transparent Conductor

Carbon3D Joe Desimone U N Carolina 3D printing (business product)

Ubiquitous Energy

Vladimir Bulović MIT Transparent Solar Cells

Does it make sense for Taiwan to invest more in energy storage technologies?

If yes, Why & How?

Cost of LIBs

DOE cost target of

$150/kWh in ~2030

Nissan LeafBattery Pack@ $270/kWh

In 2014

Li+ & e- flow in LIBs

• Li+ & e- flow in the same direction.• During charging Li+/e- flow from v+ to v-.• During discharging from v- to v+ electrode.

(Cu)(Al)

• Al (d=2.7); Cu (d=9.0)• Al: light weight; but can alloy with Li• Surface Al2O3 gives impedance. (3M has carbon coated oxide-free Al )• Energy density α Electrode thickness• High Battery Cost: $1000/kwh

Micrographs of Electrode Particles

LiCoO2

LiCoO2

LiCoO2

LiNiO2

LiNiO2

KS4 Graphite Si NP LiFePO4 Hollow flakes

LiFePO4 Particles

LiFePO4 NW

LiFePO4 Rods

LiFePO4 Flakes

NonPorous particles!

Various Form Factors of LIBs

Thin or thick electrode?

Seeo IncSolidEnergy System

US 2014/0170524 1-28. (canceled)29. An electrochemical cell, comprising: an anode;a semi-solid cathode including a suspension of about 40% to about 75% by volume of an active material and about 1% to about 6% by volume of a conductive material in a non-aqueous liquid electrolyte; andan ion-permeable membrane disposed between the anode and the semi-solid cathode,wherein, the semi-solid cathode has a thickness in the range of about 250 μm to about 2,000 μm, and wherein the electrochemical cell has an area specific capacity of at least 7 mAh/cm2 at a C-rate of C/4.

+-

Cu AlC

SepE

Key Areas & Issues in LIBs• High Voltage and High Capacity Cathodes –

- No stable and no electrolytes could be used. - Electrode coating has potential. - 3M, Umicore, BASF, Argonne, Hydro Quebec- S (1670mAh/g); O2 (>3300 mAh/g, light oxygen)

• High Capacity Anodes –-Li (3860 mAh/g) or Si (4200 mAh/g); - Li dendrite formation vs. Si pulverization. - Electrode coating has shown potential. - Li over Si, because Si anode may not work out. - Li: SolidEnergy, Seeo. Si: Amprius and various big companies

• High Voltage Electrolytes- May not be practical, - additives work may bare fruits; but can only be used for final optimization

• Polymer Electrolytes - Safer, could suppress dendrite formation and enable the use of Li metal; but need to operate at 50-90oC.- Could reduce the overall cost of LIBs and enable Li-S and Li-Air technologies.- May be used as separators, binders for electrodes, especially for Si anode – An value add.

Three Types of Cathode Materials

John Goodenough,

Not enough for Goodenough, The man who brought us the lithium-ion battery at the age of 57

has an idea for a new one at 92

http://qz.com/338767/the-man-who-brought-us-the-lithium-ion-battery-at-57-has-an-idea-for-a-new-one-at-92/

“I want to solve the problem before I throw my chips in. I’m only 92. I still have time to go.”—John Goodenough Feb 2015

Major Strategies to Improve LIB Materials

B or N doped grapheneGraphene-PNNi compositenanoparticles

List of Important Cathode Materials voltage specific

capacity (mAh/g)

energy density (wh/kg)

Conductivity

Density (g/cm3) [Tapped]

Surface area

(m2/g)

Cost ($/kg)

LiFePO4 (Fiscar) LFP O 3.4 100-160

(170)578 E-8 0.23

LiFe1/2

Mn1/2

PO4

O 3.4-4.1 160 (170)

LiMnPO4

O 4.1 171 701 E-10 LiCoPO4 O 4.8 167 802 LiNiPO4 O 5.1 167 852

LiCoO2 (toxic) (Tesla) LCO L 3.7 120-155

(274 ) 570 E-4 25

LiMnO2 L LiNiO2 (toxic) L 135-180

(274) 13

Li(Ni16/20Co3/20Al1/20)O2 NCA L 3.8 (3-4.2)

180-200 (??)

680-760 4.45 0.5

Li(Ni1/3

Mn1/3

Co1/3

)O2

Nissan & GMNMC111

BC618L 4.2-4.6 130-150

(272)597 4.8

[2.69] 0.26

Li(Ni1/2Mn3/10Co2/10)O2 1/5LiCoO2*4/5(LiMn3/8Ni2/8)O2

NMC532 ?? (164)

635

Li(Ni2/5Mn2/5Co1/5)O2 1/5LiCoO2*4/5(LiMn1/2Ni1/2)O2

NMC442 BC718

?? (155)

4.7 [2.29]

0.39

Li(Ni3/5Mn1/5Co1/5)O2 1/5LiCoO2*2/5(LiMn1/2Ni1/2)O2

NMC622

Li(Ni4/5Mn1/10Co1/10)O2 1/10LiCoO2*4/5(LiMn1/2Ni1/2)O2

NMC811

Lithium Rich Layer Oxide Li(Li1/3Mn2/3)O2*Li(Mn3/8Ni3/8Co1/4)O2 = Li(Li, Mn, Ni, Co)O2

HE-NMC (HE-NCM)

L 4.65 (5.1)

??? (250)

986

LiMn2O4 LMO S 4.3 (3.5-4.3)

100-130 (148)

500 (585)

E-4 4.29 0.5 0.5

LiMn3/2

Ni1/2

O4

(Nissan, GM)LMNO HV-spinel

S 4.7 120 (148)

651 4.45 1.3

Energy Diagrams of LIBs

Vacuum level

Li = 2.9 eV 7 eV

Coatings on cathode particles & Li metals can be viewed as preformedSEI layers. Working on preformed SEI layersIs more practical than trying to developElectrolytes with higher oxidation potentials.

Coatings on Cathodes Particles- Preformed SEI Layers

• Carbon coatings: Amorphous C, Graphene, C-PANI composites • Metal oxide coatings – Al2O3, SiO2, TiO2, ZrO2, MgO• Metal fluoride – AlF3, LaF3

• FePO4 and FePO4-PANI• Hybrid coatings of carbon – C+Li3PO4;

Dendrite Formation in LIBs•“Good” SEI formation allows Li+ to diffuse in and out of the anode.

•“Bad” SEI does not allow the flow of Li+ in and out of the anode due to both thickness issues as well as a different chemical makeup compared to good SEI. Dendritic growth of metallic Li shorts the battery after reaching the cathode.

Dendrite Suppressing Methods

• Electrolyte additives: Alkali salts (Cs+), high LiTFSI concentrations.

• Coatings on Li metal: Carbon coating• Thermal conductor coatings on separator: BN • Ionic liquids as eletrolytes.• Polymer electrolytes: block polymers, crosslinked polymers.• Pulse charging• Others

Dendrite Formation in Li ion/Li metal Batteries Yi Cui, Stanford

Mechanism of Dendrite Formation in Li ion/Li metal Batteries

This seemingly elegant method for suppressing The growth of Li dendrite was not patented.

Self-Healing Electrostatic Shield (SHES) Mechanism

•SEI layer will form once Li metal contact liquid electrolyte.

•Li ions can diffuse through SEI layer and deposit on Li surface

•SHES additives (such as Cs ions) will stay outside of SEI layer

•Formation and stability of SEI layer are the main factors affecting the Coulombic efficiency of Li deposition/stripping processes.

CsPF6 prevents dendrite formation

Coulombic efficiency is still low.

Block Copolymers as Solid ElectrolytesSeeo Inc.

PATTERNS APLENTYThese TEM images show various morphologies of polystyrene-poly(ethylene oxide) copolymers, doped with salts, that can be used in advanced batteries. Understanding the factors that control polymer structure and ionic conductivity is key to exploiting these materials.

PS = red, black; PEO = green, white; salt = blue. Credit: Nitash Balsara, UC Berkeley (Founder of Seeo Inc)

Mechanism of Dendrite Formation in Li metal Batteries

Synchrotron hard X-ray microtomography experiments on symmetric lithium–polymer–lithium cells cycled at 90 °C

Credit: Nitash Balsara, UC Berkeley

Block Copolymers as Solid Electrolytes (Seeo Inc)

Mw = 100K or 200K

50% triblockNo homopolymers

•Anionic polymers can be easily isolated in high purity•ATRP polymers have ionic and homopolymer impurities and weak ester groups.•Nitroxide Mediated Polymerization (NMP) has become the method of choice.•Too expensive.

s-BuLi EO(CH2CH2O)(CH2 CH)

PEG OHHO

BrO

BrPEG OO

O

Br

O

Br CuCl2Me6TREN

(CH2CH2O)(CH2 CH) (CH2 CH)

s-BuLi EO

Br Br(CH2CH2O)(CH2 CH) (CH2 CH)

<50% triblock

Block/Comb Polysiloxanes as ElectrolytesPolysiloxane chain has very low Tg of -123oC

D3V(CH2 CH) (Si

CH3O)

s-BuLiSi O SiH CH2CH2R1-3 (CH2 CH) (Si

CH3O)

Si O Si CH2CH2RPt cat

Si O SiH HR

RhSi O SiH CH2CH2R

•A powerful modular synthesis of functional block copolymers.•Achieved quantitative grafting for many pendant groups.•Wide range of oligoEO groups have been incorporated into R .•Highest conductivity achieved is 1x10-4 S/cm (n = 4 is sufficient), giving an operation temperature of ~50oC.•Amphiphilic polysiloxanes remain an attractive but barely explored solid electrolyte materials.•Too expansive.

(SiCH3

HO) (Si

CH3O)

R

R(SiCH3

O) (SiCH3

O)

Si O Si CH2CH2R

R = -(CH2CH2O)n-CH3 n = 3-6

Ionic Liquids as Conductivity Enhancing Additives

N

NR1

R1

R3+

CF3-SO2-N--SO2CF3

X- N+ X-

B-O

O

O

O

-Commercial materials not stable and did not give much improvement on conductivity.-Chemistry is straight forward, but purification was more involved.-One of the ionic liquid gave 10X improvement of conductivity of a polysiloxane electrolyte to 7 x 10-4 S/cm (4EO)

X- =

Si Anodes

• Yi Cui has a monopoly in this area. See https://www.youtube.com/watch?v=0Z7cEWrX9U4

• Pomegranate Si micron particles• Reduced Silica• New polymer biners • Others

Si Anodes Yi Cui -Stanford

Si Anodes Yi Cui -Stanford

Si NP from Reduced Silica

high reversible capacity of 3105 mAh g21. In particular, reversible Li storage capacities above 1500 mAh/g were maintained after 500 cycles at a high rate of C/2.

Conjugated Polymers as Binders for Si AnodeGao Liu -LBNL

peel strength

Electrode swelling

Cycling Performance

RatePerformance

Non-conjugated Polymers as Binders for Si AnodeGao Liu -LBNL

After 500 cycles After only 40 cycles

•Lower cost materials.•Work better than conjugated polymers PVDFPoly(pyrene)

Key Issues & Interests in LIBs• High Voltage and High Capacity Cathodes –

- No stable and no electrolytes could be used. - Electrode coating has potential. - 3M, Umicore, BASF, Argonne, Hydro Quebec- S (1670mAh/g); O2 (>3300 mAh/g, light oxygen)

• High Capacity Anodes –-Li (3860 mAh/g) or Si (4200 mAh/g); - Li dendrite formation vs. Si pulverization. - Electrode coating has shown potential. - Li over Si, because Si anode may not work out. - Li: SolidEnergy, Seeo. Si: Amprius and various big companies

• High Voltage Electrolytes- May not be practical, - additives work may bare fruits; but can only be used for final optimization

• Polymer Electrolytes - Safer, could suppress dendrite formation and enable the use of Li metal; but need to operate at 50-90oC.- Could reduce the overall cost of LIBs and enable Li-S and Li-Air technologies.- May be used as separators, binders for electrodes, especially for Si anode – An value add.

Summary

Solid polymer batteries with thin lithium metal anode is one of the best paths forward