<p>Paper-based flexible devices represent a new frontier
in electronics technology. The research has focused on the fabrication of the
lightweight, and flexible paper-based lithium ion batteries. A lithium ion battery relies on
the interplay of multiple components. These components themselves, as well as
the processes used to create them, need
to be adjusted and modified in order to
achieve a fully flexible lithium ion battery. These components include the
electrode current collector, active material, and electrolyte. By modifying
these components to be fully flexible and resistant to damages caused by
deformation, a fully flexible battery can be achieved.</p>
<p> </p>
<p>Herein, the paper-based platform utilized is key to
provide flexibility for the battery components.
The goal of this work not only focused on the creation of a paper-based
flexible battery to be used as an integrable energy storage system for flexible
devices, but also on developing methodologies and processes that can advance
the emerging area of paper-based electronics, where different functional units
must be fabricated within a single paper substrate. The key to make effective
paper-based batteries, is to achieve a highly conductive paper structure as the
base. In this work, conductive nanomaterials including carbon nanotubes (CNT)
and graphene were used to fabricate conductive paper, where wood microfibers
were coated with layers of these nanomaterials via layer-by-layer nanoassembly.
These fibers were then combined into paper sheets. The resulting paper offers a
conductive and porous base for electronic devices that utilized only small
quantities of CNT or reduced graphene oxide (rGO) to provide length resistances
of 468 Ω/cm and 74.6 Ω/cm, respectively for each fabricated conductive paper. </p>
<p> </p>
<p>Flexible lithium ion batteries were then made by using
CNT paper-based electrodes and a solid polymer gel electrolyte. The electrodes
were made by deposition of lithium active materials over the conductive paper
and where shown to be flexible, durable, and light weight. With respect to the
electrolyte, a new type of gel electrolyte based on PVDF-HFP was fabricated to
overcome problems related to the use of liquid electrolytes in flexible
batteries. This gel, which provides a high electrolyte uptake (450% by weight),
was made by infusing both liquid and ceramic electrolytes inside a polymer gel
structure and demonstrated conductivity up to 10<sup>-4</sup> S/cm. The
paper-based battery developed with these new materials has a comparable
capacity to commercial batteries and represents a flexible and light weight
alternative. The use of ultra-high capacity lithium compounds as cathode
materials, such as vanadium pentoxide (with theoretical capacities of 440
mAh/g) in conjunction with rGO-paper as a stand-alone electrode (with a
reversible capacity 546 mAh/g) were also explored and results will be
discussed. </p>
<p> </p>
<p>This research has led to the development of a novel
method of making a fully flexible lithium ion batteries, using paper-based
current collectors, leak proof polymer gel electrolytes and ultra-high capacity
lithium ion active materials. Thus, flexible high conductive paper-based current
collectors, polymer-gel electrolytes, vanadium based ultra-high capacity
cathode electrodes, and graphene-based stand-alone paper-based anodes have been
developed and tested.</p>
<p> </p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/9108650 |
| Date | 12 October 2021 |
| Creators | Nojan Aliahmad (5929463) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/Polymer_Electrolytes_and_Paper-based_Current_Collectors_for_Flexible_Lithium_Ion_Battery_Applications/9108650 |
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