This document describes the fabrication of a paper-based lithium-ion battery using carbon nanotube-coated wood microfibers. The wood microfibers were coated with layers of carbon nanotubes and conductive polymers using a layer-by-layer coating method. Electrodes were then spray coated onto the coated microfibers and assembled into batteries. Testing showed the paper batteries had comparable capacities to traditional batteries, provided flexibility, and used a low mass of carbon nanotubes, making them a potentially cost-effective alternative.

1. PAPER BASED LITHIUM-ION BATTERIES USING
CARBON NANOTUBE-COATED WOOD MICROFIBERS
D.SHANKAR KUMAR PATRO
1201227364
Department of Electronics and Telecommunication Engg.
C. V. Raman College Of Engineering, Bhubaneswar
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Presented by:

2. CONTENTS:-
• Introduction.
• Problems regarding batteries.
• Fabrication of C.N.T battery:-
i. LbL coating of wood microfibers with
CNT.
ii. Battery fabrication.
iii. Assembly process.
• Results and discussion.
• Conclusion.
• References.
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3. INTRODUCTION
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 Lithium-ion batteries are widely used due to their high energy densities compared to their sizes.
 These batteries are key components in portable electronics due to their high power and energy density and
long cycle life.

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Fig: Schematic of (a) half-cell and (b) full cell operation.

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 A paper battery is a flexible, ultra-thin energy storage and production
device formed by combining carbon nanotube(C.N.T) with a
conventional sheet of cellulose-based paper.
 A paper battery acts as both a high-energy battery and super-capacitor ,
combining two components that are separate in traditional electronics .
WHAT IS A PAPER BASED BATTERY?

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 Carbon nanotube is the main concept behind paper battery
 Carbon nanotubes (CNTs; also known as buckytubes) are allotropes of carbon with a
cylindrical nanostructure.
 CNTs exhibit extraordinary strength and unique electrical properties, and are
efficient thermal conductors.
 Nanotubes are members of the fullerene structural family. The diameter of a nanotube is
on the order of a few nanometers Their name is derived from their long, hollow structure
with the walls formed by one-atom-thick sheets of carbon, called graphene. These sheets
are rolled at specific and discrete angles, and the combination of the rolling angle and
radius decides the nanotube properties.
CARBON NANOTUBES:-

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PROBLEMS REGARDING OTHER BATTERIES:-
Safety issues and explosive reactions.
Low capacity and conductivity.
High fabrication costs.
Problems regarding the adherence of electrodes materials to the surface.
Battery flexibility, size and thickness.
Shorter cycle life.

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Fabrication of C.N.T battery:-
i. Layer by layer coating of wood microfibers with C.N.T:-
 The Kraft wood pulp was beaten, bleached and press dried for
microfibers,(less than 1% lignin and 99% cellulose).
 These hollow microfibers are 2-3mm in length and 35-50m in diameter.
 An aqueous dispersion of poly(3,4-ethylenedioxythiophene) and
poly(styrenesulfonate) {PEDOT-PSS} conductive polymer(3mg/mL)and
C.N.T(25mg/mL) was used as the anionic component.
 Coating of microfibers was done with 2 bilayers of PEI/CNT in alternate with one bilayer of PEI/PEDOT-PSS.
 Then the wood microfibers were assembled into flexible paper sheets.
 Poly(ethyleneimine) [PEI] (3mg/mL) was used as the cationic component.

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ii) Battery fabrication:-
Pastes of electrodes were prepared using:-
I. 85%(wt) of the active materials (Li4Ti5O12 or LiCoO2 )
II. 10% (wt) Super P lithium (obtained from Timcal, conductive material made
form carbon black of 40 nm).
III.5% (wt) Polyvinylidene fluoride (PVDF).
The electrode materials were then coated on the current collectors by a spray
coating method followed by vacuum-drying for 12 h.

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iii) Assembly process:-
 The battery configuration was assembled in an Argon filled glove box as shown-
 Then it is soaked in lithium phosphorous fluoride(liPF6),pressed and left
undisturbed for 24 h.
Fig. :- Schematic illustration of the layers of the fabricated
lithium-ion battery.

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Results and discussion:-
1) RESISTIVITY:-
Fig.:- Resistivity of the wood microfibers measured after coating each deposited
bilayer of polymer or CNT. The error bars indicate the minimum and
maximum of the measured resistivity with the data points showing the mean
values.
These tests were carried out in Arbin BT200 battery testing system:-

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2) COATING OF MICROFIBERS :-
Fig. :- SEM images of (a) uncoated and (b) CNT-coated microfibers.

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3) Adherence to the substrate :-
Fig:- SEM images showing the cross section of LCO and LTO layers on CNT-microfiber paper
current collectors

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4) Mechanical flexibility :-
Fig:- SEM images of samples bent to a 300◦
angle for 20 times:
(a) LCO on CNT-coated microfiber current
collector,
(b) LTO on CNT-coated microfiber current
collector
(c) LCO on Aluminium foil, and
(d) LTO on Copper foil.

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5) Half cell and full cell charging capacities :-
Type of battery Charging
capacity
Mass loading
Cu and Al current
collectors
LCO-149mAh/g
LTO-156mAh/g
Anode(LTO)-8.8mg/𝑐𝑚2
Cathode (LCO)-9.2mg/𝑐𝑚2
C.N.T microfibers
current
collectors
LCO-150mAh/g
LTO-158mAh/g
10.1g/𝑐𝑚2
The above results show that the cells are less stable
with less than 1% drop from 1st to 15th cycle
The columbic efficiency =84%(1),96%(2),stays at
96%-98% thereafter.

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continued :-
Fig:- Galvanostatic charging/discharging curves of the
half-cells made of CNT-microfiber paper current
collectors. (a) LCO half-cell 1st and 15th cycles.
(b) LTO half-cell 1st and 15th cycles.

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6) Self discharge :-

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Conclusion:-
 Lithium-ion batteries with CNT-microfiber paper-based current collectors have been
developed.
 The capacities are comparable with traditional batteries.
 The paper structure provides flexibility and better interface/adhesion for active materials.
Moreover, the LbL coating method uses only 10.1 μ g/cm2 of CNT, thereby making the
developed lithium-ion paper-based battery cost effective.
 Batteries with CNT-microfiber paper current collectors have a wide range of electronic
applications as they provide flexibility, lightweight, and high capacity features.

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References :-
 “Paper based lithium ion batteries using carbon nanotube-coated
wood microfibers” , Nojan Aliahmad, Mangilal Agarwal, Sudhir
Shrestha, Kody Varahramyan , IEEE transactions on Nanotechnology,
vol.12, no.3, May 6, 2013.
 L.Hu, H.Wu, F. LaMantia,Y.Yang, andY. Cui, “Thin, flexible secondary
Li-ion paper batteries,” ACS Nano, vol. 4, pp. 5843–5848, 2010.

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