http://www.clemson.edu/ces/conductingpolymers/ Roberts Research Group

Functional Polymers for Supercapacitors and Batteries

Mark E. Roberts, Ph.D.Assistant ProfessorChemical and Biomolecular Engineering

mrober9@clemson.edu

http://www.clemson.edu/ces/conductingpolymers/ Roberts Research Group

Polymer & Organic Chemistry Material & Electrode Processing

Device FabricationElectrochemical Analysis

Group Expertise

PS

substrate

refct

Electrochemical

Chemical Vapor

PhysicalCoating

50 µm

flexible

Coin cells

substratepolymer

Conducting polymers

Structure-driving groups

Localized redox processes

Extensive Material Diversity

http://www.clemson.edu/ces/conductingpolymers/ Roberts Research Group

Polymer Electrode Design Responsive Polymer Electrolytes

Research Areas

Polymer based electrodes are designed to achieve High-Power and High-Energy Density energy storage devices.

Responsive electrolytes are developed to achieve thermal control in electrochemical cells.

The phase behavior of polymer electrolyte solutions can lead to unique temperature dependent properties.

The structure and performance of polymer electrodes can be tailored through synthetic design.

2cm

Kelly, et al., Adv. Mater., 2012, 24, 886.

http://www.clemson.edu/ces/conductingpolymers/ Roberts Research Group

Current Technology Limitations High-power and high-energy density devices are needed for:

High Power, High Energy Electrodes

Renewable Energy Generation

Transportation

With existing materials and devices, we must pick between either High Power (capacitors) or High Energy (Batteries)

Why not both?

High-Power,High Energy

http://www.clemson.edu/ces/conductingpolymers/ Roberts Research Group

Conducting Polymer Design Redox Molecule Dopants

Conducting Polymer Solutions

Polymer NanoStructures

Arcila-Velez & Roberts, Chem. Mater., 2014, 26, 1601.

Arrays of micro/nano-structures over large areas

Increasing Polymer

Carbon-Polymer Composites

Kearns & Roberts, J. Mater. Chem., 2012, 22, 2392.

http://www.clemson.edu/ces/conductingpolymers/ Roberts Research Group

Safety Hazards of Li-ion Batteries State-of-the-art solutions to mitigate thermal hazards:

Responsive Polymer Electrolytes

In large format batteries, high-power demands (fast discharge) lead to thermal instabilities that can cause fires and explosions.

1) Separators with a central layer that melts above unsafe operating temperatures (destructive):

2) Solid-state polymer separators with lower ionic conductivity (low discharge rates)

Small format cells have low power requirements and heat generation(low safety hazards)

http://spectrum.ieee.org/

polypropylene

polyethylene

polypropylenewww.celgard.com/

http://www.clemson.edu/ces/conductingpolymers/ Roberts Research Group

Electrolyte Design for Li-ion Batteries

Temperature-Responsive Optical and Electrochemical Properties

Responsive Polymer ElectrolytesPolymer phase behavior is studied in ionic liquids and organic electrolytes. Polymer properties and salt concentration affect the thermal transition and conductivity.

Solutions undergo a thermally-activated phase separation above a given temperature. Conductivity and charge transfer significantly decreases due to the formation of a resistive polymer layer.

Increasing temperature

NNBF4–

Li+ BF4–H

OOHn

NNBF4–

HO

OHn

Low conductivity

High conductivity

http://www.clemson.edu/ces/conductingpolymers/ Roberts Research Group

Research Team

Graduates• Jesse Kelly• Margie Arcila• Kryssia Diaz• Matt Noor

Undergraduates• Robert Emmett, Timothy Bate• Sam Leguizamon, Andrew Carlin• Kyle Vassallo, Nicholas Degrood

Collaborators• Apparao M. Rao• Rama Podila• Anthony Guiseppi-Elie• Stephen Foulger• Mark Thies

• Dave Wheeler (SNL)• Dale Huber (SNL)

FUNDING