TG-MS of Anode Active Material forLithium-ion Batteries

Introduction

Lithium-ion batteries are widely used as batteries for mobile applications such as notebook PCs and mobile phones, and are also applied to automobiles. In order for batteries to operate safely, it is important to understand the thermal stability of the constituent materials. Here, the thermal decomposition behavior of the anode active material was successfully investigated by TG-MS. 

Analysis example

LiCoO₂ and LiMn₂O₄ standard materials were heated at 20°C/min from room temperature up to 1200°C in a He atmosphere. Electron ionization mode (EI) was used in MS. Figure 1 shows the TG-MS measurement results. The mass loss of LiCoO₂ was observed from around 1000°C, indicating the evolution of O₂ (m/z 32). In addition, CO₂ (m/z 44) derived from impurities was evolved around at 500°C. On the other hand, LiMn₂O₄ has a two-step mass loss at around 800°C and 1100°C, and O₂ was evolved in each step. Furthermore, the evolution of SO₂ (m/z 64) derived from impurities was confirmed around at 1000°C.

Figure 1: Thermal behaviors of TG and MS signals for (a) LiCoO₂ and (b) LiMn₂O₄. The numbers in parentheses are the magnification of the signal intensity in each ion.