Werkstoffforschung in der Batterietechnik

Philipp AdelhelmInstitute for Technical Chemistry and Environmental ChemistryCenter for Energy and Environmental Chemistry (CEEC Jena)Friedrich‐Schiller‐University Jena, Germany

Thüringer Werkstofftag 2017, 30.3.2017, Jena

Different technologies for rechargeable batteries

500

400

300

200

100

00 50 100 150 200 250 Energy by weight

(Wh/kg)

Energy by volume(Wh/L)

Li‐ion technology

NiCd

NiMH

lighter

smaller

Pb‐acid

Future high energychemistry?

Future low costchemistry?

Lithium‐ion batteries – The limits?

Are we reaching the limits? How important is safety?

Graph: data redrawn from Fraunhofer ISI report Dec. 2015

Lithium‐ion batteries: Materials

LiCoO2Li[Ni1‐x‐yMnxCoy]O2Li[Ni0.8Co0.15Al0.05]O2LiFePO4LiMn2O4

Graphite (LiC6)…

anode cathode

• Remember: „The Li‐ion battery“ does not exist! Many variations are on the market.

• The main difference between the various types is due to the different materials thatare used for the positive and negative electrode. 

• Which material combination is used, depends on the application.

Materials for lithium‐ion batteries – A typical EV battery

60 kWh (435 kg) ca. 350 km

An estimate*:

* Estimate includes active materials and current collectors only. Values calculated assuming Graphite/NMC cells

Li 6.5 kgCo 18  kgMn 17  kgNi 18  kg

Graphite 45 kgCu 60 kgAl 37 kg… …

Materials for lithium‐ion batteries – Supply

From: „Bottleneck“ materials for the deployment of low‐carbon technologies in the EU. Dr. V. Tzimas, JRC, 23 Feb 2017

Approaching the limits: Energy density

EC

EA

W = QU

++

Higher capacity: More lithium‐ions per electrode mass and volume

anode cathode

LithiumGraphite (LiC6)Other carbons (Li1+xC6)Si (Li4.4Si)Sn (Li22Sn5)…

Task for materials scientists:Replace graphite by metal alloys or use even pure lithium!

Alloys: Up to 10x higher capacity than graphite but poor cycle lifeLithium: Highest capacity but unsolved safety issues for decades

Higher capacity: More lithium‐ions per electrode mass and volume

LithiumGraphite (LiC6)Other carbons (Li1+xC6)Si (Li4.4Si)Sn (Li22Sn5)…

anode cathode

Higher capacity:Replace graphite by metal alloys or use even pure lithium!

Alloys: Up to 10x higher capacity than graphite but poor cycle lifeLithium: Highest capacity but unsolved safety issued for decades

discharge +

chargeLi   Li e

Higher capacity: More lithium‐ions per electrode mass and volume

anode cathode

LiCoO2Li[Ni1‐x‐yMnxCoy]O2Li[Ni0.8Co0.15Al0.05]O2LiMn2O4LiNi0.5Mn1.5O4Overlithiated NMC

Task for materials scientists:Increase content of nickel, eventually overlithiate materials!

Nickel: Higher capacity + higher voltage but lower cycle lifeOverlithiate: Much higher capacity but voltage fade

Higher capacity: More lithium‐ions per electrode mass and volume

Li[Ni1-y-zCoyMnz]O2 („NMC“… or sometimes „NCM“, or „MNC“, depending on what people prefer)

0.0 0.2 0.4 0.6 0.8 1.0

0.0

0.2

0.4

0.6

0.8

1.0 0.0

0.2

0.4

0.6

0.8

1.0Co (LCO)

Ni (LNO)Mn (LMO)

High capacity –low safety region

Classic highstability region

Lower cost region

NiComposition Diagram

State‐of‐the art compositions in application are NCM 111, NCM 523, NCM 424. But NCM 811 is aimed for!

Rule of thumb:

More Ni: Higher capacityMore Mn: Lower price, better thermal stabilityMore Co: Better cycle life

Improving Li‐ion technology

anode cathode

Better electrolytes!

Improving Li‐ion technology: Better electrolytes

Source: Diagram data from R. Stringfellow et al. TIAX, 2010; presented byJ. Garche, AABC Europe, 2016

In case of fire, roughly 2/3 of the heat release is due tocombustion of the organic electrolyte! Also quite some HF is 

released (30 – 100 g HF per kWh).

Improving Li‐ion technology: Better electrolytes

anode cathode

Polymer electrolytes: Studied for more than 35 years but nocommercialization yet.Solid electrolytes: Quite recent topic, high risk high gain. Toyota isfrontrunner.

Lithium‐ion is not enough: Next generation systems

P. Adelhelm et al., Beilstein J. Nanotech, 2015

Li/O2 batteries – maximizing energy density

Discharge

2 2 2Charge2 Li O ( )    Li Og

Cell reaction:

E° = 2.96 Vwth = 3460 Wh/kg(MO)

Concept introduced 1996 by K.M. Abraham, J. Electrochem Soc., 1996, 143, 1‐5

Li/S batteries – maximizing energy density

Image Source: Ken Cooper Photography

Discharge

8 2Charge2 Li 1/8 S    2 Li SCell reaction: E° = 2.24 V, wth = 2615 Wh/kg

2Li + 1/8 S8 Li2S8 Li2S6        Li2S4 Li2S2 Li2S

solublenon‐conducting solid non‐conducting solid

Li/S batteries – maximizing energy density

Image Source: Ken Cooper Photography

Discharge

8 2Charge2 Li 1/8 S    2 Li SCell reaction: E° = 2.24 V, wth = 2615 Wh/kg

2Li + 1/8 S8 Li2S8 Li2S6        Li2S4 Li2S2 Li2S

solublenon‐conducting solid non‐conducting solid

Improving Li‐ion technology: What else?

anode cathode

Improving Li‐ion technology: What else?

anode cathode

Replace Li+ by Na+, K+, Al3+, Mg2+,…

Reserves as an advantage for sodium

C. Wadia et al., Journal of Power Sources, 196, 2011

LIB vs. NIBs – LCO and NCO as example

P. Adelhelm, Nachrichten aus der Chemie, 12/2014

LCO and NCO do not compare at all!LCO: mainly solid solution behaviorNCO: very complex phase behavior related to ordering of Na+ vacancies and

[CoO2]‐layers

• High overpotentials• Low discharge capacities

Li/O2 vs. Na/O2: Voltage profile

j = 20 µA∙cm−2

Lithium/oxygen cell: Sodium/oxygen cell:

j = 200 µA∙cm−2

P. Hartmann et al., Nature Materials, 12, 2013C. L. Bender et al., Adv. Energy Mater., 4, 2014C. L. Bender et al., Angewandte Chemie Int. Ed., 55, 2016

• Low overpotentials• High discharge capacities

Li2O2 NaO2

Conclusion

• Lithium‐ion battery technlogoy is constantly improved and will dominate the rapidly growing market. Energy density increases at a rate of 5 – 10 % per year, but we will likely reach the limits soon(energy density vs. safety).What will be the role of Europe andGermany?

• A range of alternative materials is studied intensively worldwidemostly with the aims of increasing capacity and/or cell voltage. This is challenging and often incremental work characterized byfine‐tuning the composition and amounts of all batterycomponents.

• Disruptive technologies can, but might not, change the game: Lithium‐air, lithium‐sulfur, solid state batteries, Sodium, Magnesium,….  

Acknowledgment

Battery and Electrochemistry Network

and Prof. Jürgen Janek, Dr. Pascal Hartmann, Dr. Ricardo Pinedo, Dr. Amrtha Bhide, Dr. Conrad Bender, Dr. Sebastian Wenzel, Dr. Birte Jache, Dr. Franziska Klein, Christine Eufinger, Martin Busche

Jena team:Dr. Prasant NayakWolfgang BrehmMustafa GöktasLukas Medenbach

Santosha LingamurthyLiangtao YangDr. Thangavelu Palaniselvam

Master students: Jonas Geisler, Ines Escher, Thomas Blesch, Shan Liu, Marie‐Ann Schmid