Thermal Stability Studies of Li‐Ion Cells and Components

Abstract

Thermal stability of fully charged 550 mAh prismatic Li-ion cells (Sn-doped LiCoO 2 /graphitic carbon) and their components are investigated. Accelerating rate calorimetry (ARC) is used to determine the onset temperature of exothermic chemical reactions that force the cell into thermal runaway. Differential scanning calorimetry (DSC) and thermogravimetry analysis are used to determine the thermal stability of the cell's positive electrode (PE) and negative electrode (NE) materials from 35 to 400ЊC. The cell selfheating exothermic reactions start at 123ЊC, and thermal runaway occurs near 167ЊC. The total exothermic heat generation of the NE and PE materials are 697 and 407 J/g, respectively. Heat generations of the NE and PE materials, washed in diethyl carbonate (DEC) and dried at Ϸ65ЊC under vacuum, are significantly lower than unwashed samples. Lithium plating increases the heat generation of the NE material at temperatures near the lithium melting point. Comparison of the heat generation profiles from DSC and ARC tests indicates that thermal runaway of this cell is close to the decomposition temperature range of the unwashed PE material. We conclude that the heat generation from the decomposition of PE material and reaction of that with electrolyte initiates thermal runaway in a Li-ion cell, under thermally or abusive conditions.

Characterization of Lithium-Ion Battery Thermal Abuse Behavior Using Experimental and Computational Analysis

“…The heat released during the negative-solvent reaction can often be enough to initiate this reaction. The rate of the positive-solvent reaction is given as [20] dα dt = −R pe [21] where Q pe (W m −3 ) is the volumetric heat generation, H pe (J kg −1 ) is the specific heat release, and W pe (kg m −3 ) is the active material content per volume in the cathode.…”

“…• C. 19,20 The generated heat is caused by the decomposition of the meta-stable component of the SEI layer and decreases as this species is consumed. It was shown that the heat release was independent of the amount of intercalated lithium but was very sensitive to the surface area of the anode, as this increased the amount of meta-stable SEI.…”

Large format lithium ion pouch cell full thermal characterisation for improved electric vehicle thermal management

“…In addition to safety concerns, the temperature sensitivity of the conductivity of the organic electrolyte makes lithium ion battery properties , 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 and accelerating ageing further in a positive feedback loop manner. The increased heat generation adds extra cooling requirements to the cooling system and may have catastrophic consequences such as thermal runaway if the cell temperature cannot be managed to an appropriate level throughout battery life for a range of different environmental conditions and use cases [10,11,20].…”

Thermo-Chemical Process Associated with Lithium Cobalt Oxide Cathode in Lithium Ion Batteries

“…After the nail was inserted the cell did not ignite but reached a maximum temperature, 380°C. In (Maleki et al, 1999), the thermal stability study of fully charged 550mAh prismatic lithium ion cell and the components inside the cell showed that the self-heating exothermic reactions starts at 123°C, and thermal runaway at 167°C. The report also brings out that the total exothermic heat generation of the NE and PE materials is 697 and 407 J/g respectively.…”