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About this book

This book describes in detail the use of natural cellulose fibers for the production of innovative, low-cost, and easily recyclable lithium-ion (Li-ion) cells by means of fast and reliable papermaking procedures that employ water as a solvent. In addition, it proposes specific methods to optimize the safety features of these paper-based cells and to improve the electronic conductivity of the electrodes by means of a carbonization process– an interesting novel technology that enables higher current rate capabilities to be achieved. The in-depth descriptions of materials, methods, and techniques are complemented by the inclusion of a general overview of electrochemical devices and, in particular, of different Li-ion battery configurations. Presenting the outcomes of this important research, the work is of wide interest to electrochemical engineers in both research institutions and industry.

Table of Contents

Frontmatter

Introductory Section

Frontmatter

Chapter 1. Electrochemical Power Sources

Abstract
This Chapter provides the basis for approaching the world of electrochemical generators. An electrochemical cell is a device capable of either generating electrical energy from chemical reactions or facilitating chemical reactions through the introduction of electrical energy. In the first paragraph, it is explained the working principles of a cell. After that, a glossary that outlines the technical terms and the unit of measurement required for a scientific study of electrochemical generators is embedded. The Chapter ends with an overview of the principal typology of secondary batteries exploited nowadays.
Lorenzo Zolin

Chapter 2. Lithium-Based Batteries

Abstract
This chapter concerns, in an introductory manner, the heart of this monograph. Lithium-ion batteries are common in consumer electronic and are also growing in popularity for military, battery electric vehicle and aerospace applications, because of their characteristics of high energy density, small memory effect and only slow loss of charge when not in use. The Chapter starts with a brief history of the Lithium based electrochemical devices, followed by an explanation of the market needs. After that, the main characteristics of this typology of battery are emphasized and the working principle of the intercalation compounds explained. The chapter is closed with a deep overview of the materials used as anode, cathode, separator, electrolyte and binder for the Lithium-ion cells.
Lorenzo Zolin

Chapter 3. Cellulose and Cellulose Derivatives in Li-Ion Batteries

Abstract
This chapter concerns the state of art of the use of cellulose for electrochemical devices. Cellulose constitutes the most abundant, renewable polymer source available worldwide today. Moreover, cellulose fibers have low cost, excellent mechanical proprieties and easy processability. The Chapter starts with a description of this polymer and of the treatments needed to obtain cellulose derivatives, in exemplum microfibrillated cellulose. At the end, the electrochemical devices that exploited paper either as electrodic binder or as separator before this research work was performed are briefly examined.
Lorenzo Zolin

Experimental and Results Section

Frontmatter

Chapter 4. Methods and Materials

Abstract
This chapter, will be given a brief description of the materials and methods (and relative main characteristics) used in the course of my research activities well as the structural/morphological and electrochemical characterization techniques (and relative components and testing devices).
Lorenzo Zolin

Chapter 5. Electrode Preparation Exploiting Filtration

Abstract
In order to reduce the costs as well as increase the production throughput of cellulose-bonded electrodes, the use of cellulose fibers (FB) as binder for both anode and cathode was investigated. Electrodes were prepared by means of a water-based filtration process as in common papermaking methods. Prior to electrode preparation, cellulose fibers were mechanically treated (beaten), following the procedure detailed in Sect. 4.​3, in order to produce external fiber fibrillation and the typical enhancement of fibers bonding characteristics [1]. The proposed production process is eco-friendly, low cost and easily up-scalable, capitalizing the well-established papermaking techniques and the obtained paper-electrodes are flexible and self-standing.
Lorenzo Zolin

Chapter 6. Electrode Preparation Exploiting the Spray Coating Technique

Abstract
A new spray coating water-based process is here proposed for the rapid and reliable large-scale production of self-standing Li-ion battery electrodes with truly natural microfibrillated cellulose as binder and a cellulose sheet as support. In such a process, the slurry comprising the active materials (i.e., GP or LiFePO4), the carbon black (CB) conductivity enhancer and the microfibrillated cellulose (MFC) binder is spray coated on a wet paper substrate which, after being pressed and dried on a conventional pilot paper machine, leads to the formation of a bilayered electrode. The newly elaborated electrode demonstrates excellent mechanical properties and cycling performances in Li metal cell configuration comparable to those of electrodes with standard composition. In the course of this chapter, the well-established industrial papermaking techniques and materials will be demonstrated to be adaptable to the elaboration of well-performing electrodes, thus paving the way for the transfer the Li-ion battery industrial area of high-throughput paper production technologies.
Lorenzo Zolin

Chapter 7. Li-Ion Cell Separator

Abstract
Despite the high number of research articles regarding the development of new high performance electrolytes for Li-ion batteries, relatively little work has been carried out for the investigation of green, mechanically robust, safe and commercially applicable paper separators. In this work, newly elaborated paper separators made of natural cellulose fibres are prepared by filtration dewatering. Paper separators show high porosity, wettability and mechanical robustness along with remarkable ion transport characteristics. This unravels the possibility of implementing the newly elaborated paper separators in safe, green and cost effective energy storage devices especially as they are obtained by rapid, low-cost and eco-friendly water-based paper-making techniques. In the second part of the Chapter a polymer separator reinforced with MFC is examined. It offers several advantages over liquid electrolyte by substituting conventional flammable and volatile solvents with a polymer electrolyte; moreover, the addition of MFC improves battery safety and mechanical strength, increasing design flexibility.
Lorenzo Zolin

Chapter 8. Carbonization Procedure Towards Highly Conductive Paper Electrodes

Abstract
A new carbonization process is here proposed for the production of highly conductive, self-standing Li-ion battery electrodes. In such a procedure, the paper electrodes obtained as shown in Chap. 6 (i.e., with truly natural microfibrillated cellulose as binder and a cellulose sheet as support) are treated at 600 °C in a furnace under nitrogen flux. In this way, both the MFC fibres and the FB sheet get carbonized; the resulting electrodes, despite decreased mechanical characteristics which nevertheless do not fully jeopardize their hand ability, demonstrate significantly higher electronic conductivity, since the binding network composed by insulating MFCs turns into conductive carbonaceous fibres upon annealing. Moreover, the cellulose handsheet support gets converted into a conductive carbon-paper sheet which can serve as embedded current collector to rapidly transfer the electrons to the external circuit. In the course of this chapter the carbonization procedure will be described and the effective prospects of this method will be demonstrated in increasing the performance of paper electrodes, as a result of the highly increased electrochemical performances and, in particular, the power output which allows to use this carbonised paper electrodes in more power demanding applications.
Lorenzo Zolin

Backmatter

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