NEW DESIGN CONCEPTS FOR HIGH-CAPACITY BATTERY MATERIALS CARSTEN STREB INSTITUTE OF INORGANIC CHEMISTRY I ULM UNIVERSITY CARSTEN.STREB@UNI-ULM.DE WWW.STREBGROUP.NET WORLD MOBILITY SUMMIT 2016 OCTOBER 20TH 2016 1
Agenda 1. Challenges in battery development 2. Metal oxides in battery electrodes 3. New concepts for high capacity batteries
Ulm Battery Research Facilities Center for solar energy and hydrogen research Helmholtz-Institute for Battery Research Ulm Ulm University
Current mobility technology: Fossil fuels CO 2 release Crude oil Petrol Global warming X CO 2 concentration in Earth atmosphere: 1900: ca. 0.3 % 2015: > 0.4 %
Batteries vs chemical fuels Why are fossil fuels so important to modern society? Material Petrol 10 Methanol 4 H 2 (700 bar) 1.5 Lithium ion battery 0.2-0.4 Energy density (kwh/liter) Chemical fuels have significantly higher energy density than batteries, i.e. less transportation volume (and weight!) is required In addition, fossil fuels are the basis for most man-made materials (plastics, pharmaceuticals...), so simply burning them is rather wasteful! source: wikipedia.com
State of the art Lithium ion batteries Lithium market demand 2015 Projected Lithium demand 2015-2024 Lithium prices are highly volatile! source: zerohedge.com
Challenges in global Lithium supplies Two main product lines Tesla car batteries PowerWall stationary batteries Target: Produce more Lithium ion batteries in 2020 then were produced globally in 2013. The Gigafactory will use >20 % of the annual global Lithium supply Up to 10 more gigafactories are under consideration worldwide. Lithium supplies will become critical Lithium price will likely increase significantly Post-Lithium battery concepts are required
State of the art Lithium ion batteries Why is Lithium so important for batteries? Low atomic weight Small atomic size High redox-potential Low battery weight (compare e.g. to lead batteries!) Fast Lithium transport (fast charging-discharging) High energy density (at low volume and weight)
Lithium ion batteries Working principles of a Lithium ion battery: Electrons (-) and Lithium ions (+) are stored in the anode Upon discharge, the electrons pass through an external circuit, delivering electrical energy Per electron, one Lithium ion is transported internally from the Anode to the Cathode Transport of electrons and Lithium ions within the electrodes limits key performance parameters such as maximum power density, charging-discharging times, etc.
Typical metal oxide electrodes face the following issues: Low electrical conductivity limits battery performance Slow Lithium transport also limits performance Fast charging/discharging can result in electrode decomposition Challenges in electrode design Overcome charge transport limitations by maximizing the contact between metal current collector and metal oxide electrode. Metal oxide electrode Metal current collector Critical materials design tasks: New electron storage materials New electron transport materials Connect both components!
NEW DESIGN CONCEPTS FOR HIGH CAPACITY BATTERY MATERIALS 1 11
Our design concepts Charge storage Charge storage: Molecular metal oxides Charge transport Charge transport: Conductive Carbon Nanotubes (CNTs)
Carbon nanotubes as conductive substrate What are Carbon Nanotubes (CNTs) CNTs are a different type (modification) of carbon, just like graphite or diamond. Think of a CNT as a rolled-up single layer of graphite single-layer graphite (graphene) Carbon Nanotube Key properties: High electrical conductivity High mechanichal and chemical stability Can be interfaced with various electrode materials 200 nm 13
Molecular metal oxides for charge storage What are Molecular Metal Oxides (MMOs) MMOs are nanostructured molecules made up from metals and oxygen. Think of a MMO as a small piece cut out of a large metal oxide sheet solid-state metal oxide (e.g. iron oxide - rust) Molecular Metal Oxide Key properties: High electrical storage capacity Properties can be widely tuned Can be interfaced with various conductive materials 14
Review: Y. Ji, L. Huang, J. Hu, C. Streb, Y.-F. Song, Energ. Environ. Sci. 2015, 8, 776-789 Molecular Cluster Batteries
Structure of MMO-CNT composites MMO-CNT-composites for Lithium ion batteries CNT MMO Y. Ji, L. Huang, J. Hu, C. Streb, Y.-F. Song, Energ. Environ. Sci. 2015, 8, 776-789
Controlling fundamental composite properties MMO-CNT-composites for Lithium ion batteries Y. Ji, L. Huang, J. Hu, C. Streb, Y.-F. Song, Energ. Environ. Sci. 2015, 8, 776-789
Controlling fundamental composite properties MMO-CNT-composites for Lithium ion batteries Y. Ji, L. Huang, J. Hu, C. Streb, Y.-F. Song, Energ. Environ. Sci. 2015, 8, 776-789
Battery performance tests MMO-CNT-composites for Lithium ion batteries Promising storage capacity Good cycling stability Y. Ji, L. Huang, J. Hu, C. Streb, Y.-F. Song, Energ. Environ. Sci. 2015, 8, 776-789
Materials optimization MMO-CNT-composites for Lithium ion batteries ca. 2500 MMOs Maximize MMO distribution on CNTs Y. Ji, L. Huang, J. Hu, C. Streb, Y.-F. Song, Energ. Environ. Sci. 2015, 8, 776-789
HR-transmission electron microscopy Single-MMO deposition on CNTs Y. Li, J. Hu, L. Huang, W. Chen, C. Streb, Y.-F. Song, Chem. Eur. J., 2015, 21, 6469-6474
Summary Take-home messages New materials offer significant benefits for Lithium ion batteries Fundamental, molecular level insight enables knowledge driven materials development Close ties between industry and academia are required to develop new and technologically relevant battery concepts
Thank you very much Co-workers: PhD students: Stefanie Schönweiz Benjamin Schwarz Xiaolin Xing Ashwene Rajagopal Yuanchun Ji Montaha Anjass Archismita Misra Amirouche Maza Undergraduates Magdalena Heiland Sebastian Knoll Manuel Lechner Lea Kremer Collaborations Prof. Sven Rau (Ulm) Prof. Yu-Fei Song (Beijing) Prof. Alan Bond (Monash) Prof. Benjamin Dietzek (Jena) Prof. Timo Jacob (Ulm) DAAD FCI 23