Thermodynamic study of lithium-ion battery materials
- PDF / 1,160,486 Bytes
- 14 Pages / 612 x 792 pts (letter) Page_size
- 79 Downloads / 293 Views
Thermodynamic study of lithium-ion battery materials
Denis Y.W. Yua, Yvan Reynierb, Joanna Dodd Cardemab, Yasunori Ozawab and Rachid Yazamia,b a
b
Energy Research Institute @ NTU, Nanyang Technological University, Singapore 637553, Singapore
CNRS-Caltech Materials for Electrochemical Energetics Laboratory, California Institute of Technology, MC 138-78, Pasadena, CA 91125, USA
Abstract The ability to monitor the status of a battery during charge and discharge is important for predicting its performance and life. This is typically done by measuring the voltage and resistance across the terminals, or by external characterization methods such as X-ray diffraction and Raman spectroscopy. Thermodynamics measurements based on entropy and enthalpy provide another mean to “look inside” a battery, giving us more information to determine the state of health of the battery. In particular, entropy undergoes drastic changes at boundaries of phase transitions taking place in each electrode material at defined states of charge (lithium stoichiometry). Recent work on thermodynamics study on lithium ion battery materials is summarized in this paper. Introduction Lithium-ion batteries can be found in almost all electronic devices and the market share continues to grow. Understanding the behavior of the batteries is becoming more and more important, especially when the cell size gets bigger and bigger. Typically battery materials are characterized by their electrochemical behavior, by either applying a voltage to a cell and studying the resulting current that is needed to drive the cell, or by applying a current to see how the voltage of the cell reacts. At the same time, the electrochemical properties of battery materials are highly dependent on the structure of the material. In-situ experiments such as x-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy have been applied to study how the structures of materials change during charge and discharge. These experiments can give excellent insights into the underlying mechanism of the materials. However, most in-situ experiments require either special sample setups or special equipments and cannot be applied directly to commercial batteries. It would therefore be important to have a general method that can monitor the structural change of battery materials in a commercial battery without opening up the cell. It is known that chemical states can be described by thermodynamics, and by monitoring the thermodynamics of a battery, the status of the battery material can be known. In particular, information on the phase transition of material, state of charge, state of health of the battery can be obtained with the electrochemical thermodynamics measurement (ETM). This is an active research area that was dated back to the 1980s1, and the technique has been applied to various cathode and anode materials since then. Since ETM method is applicable to any chemical cells, we expect the method can give insights into new materials and applications in the future.
Data Loading...
