Concept and feasibility study of self-organized electrochemical devices
Name
1196185530-MIT.pdf
Size
8.13 MB
Format
Adobe PDF
Checksum (MD5)
3a096d5cf9ed07b4a510a7d14d393bdb
Author(s)
Moorehead, William Douglas,S. M.Massachusetts Institute of Technology.
Advisor(s)
Yet-Ming Chiang.
Date Issued
2002
Publisher
Massachusetts Institute of Technology
Abstract
Since Volta's discovery of " an electric battery" in 1800, advancements have proceeded due to great materials advances. However, the basic configuration he proposed then is still present in today's portable power sources. In this work, using attractive and repulsive London-van der Waals forces, a self-organized, interpenetrating, separator-free rechargeable lithium ion battery called a self-organized battery system (SBS) is proposed. In this design, a repulsive interaction between the cathode and anode is used to establish the basic electrochemical junction. Increases in both energy density (Wh/kg, Wh/1) and power density (W/kg, W/1) are possible from such a design, due to 1) the decrease of inactive materials required, and 2) the decrease in Li ion diffusion length between the cathode and anode. The sign of the Hamaker constant (A₁₂₃) determines either attraction (+) or repulsion(-) where material 2 is the intervening material between materials 1 and 3.
For low refractive index materials (n<2), A₁₂₃ is determined primarily by the average refractive index of materials 1,2, and 3 in the visible range. For a repulsive interaction, where A₁₂₃<0, the refractive index of materials 1,2, and 3 must be n₁n₂>n₃ All close packed oxide cathode structures (LiMO₂,where M=Mn, Co, Ni) that are currently used in Li ion technology have refractive indexes >2. However, a new class of cathode materials based upon the olivine, LiFePO₄, allows n₁
Electronic isolation between the conductive polymer blend and both MCMB and Mg-doped LiCoO₂ was achieved as well as between doped LiFePO₄ and MCMB. Electrochemical cycling was performed on several SBS cells. Upon electrochemical cell assembly, open circuit voltages were observed. Upon cycling, The cell voltages observed upon intercalation are thermodynamically consistent with the cathode and anode materials present in the systems. Comparisons to conventional cells using Celgard separator between the cathode and anode are made.
Description
Thesis: S. M., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2002
Cataloged from the PDF of thesis.
Includes bibliographical references.
Subjects
Materials Science and Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering
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