Modification of Bacterial Cellulose Membrane as a Separator for Lithium Ion Batteries

• Main Authors: Pei-Ying Lin, 林佩穎
• Other Authors: Chi-Wen Lin
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/02450058122128993393

碩士 === 國立雲林科技大學 === 化學工程與材料工程系碩士班 === 101 === This study attempts to propose an effective method in order to eliminate the troublesome hydroxyl groups of bacterial cellulose (BC) membrane while preserving its microfibrillar morphology for its possible application in lithium-ion battery (LIB). A fibrous acetylation method is adopted to modify BC membrane for this purpose. Furthermore, it is found that different drying methods can also lead to different morphology and have a profound influence on the physical properties of the BC separator. Under fixed compositions but different reaction durations for acetylation treatment, it is observed that acetylation reaction for 60 min (i.e. corresponding to a degree of substitution, DS = 1.65) followed by freeze drying is an optimum condition to modify a BC membrane. The corresponding membrane, referred as FA60BC, exhibits excellent properties in thermal stability (nearly zero shrinkage under 150 ℃ for 30 min), electrolyte uptake (up to 279 %), and wettability for liquid electrolyte solution. The ionic conductivity of the FA60BC membrane was 0.58 mScm-1, close to the value of 0.64 mScm-1 of the commercial Celgard 2325 membrane. A lithium-ion cell assembled with the FA60BC separator showed stable cycling performance and high rate capability. Linear sweep voltammetry (LSV) test indicates the FA60BCseparator is even superior to Celgard 2325 in electrochemical stability window. This preliminary study indicates BC membrane is very promising to act as a separator in LIB.