Factors Influencing the Thermal Stability of Lithium Ion Batteries - From Active Materials to State-of-Charge and Degradation JRC Exploratory Research Workshop – Safer Li-Ion Batteries by Preventing Thermal Propagation? M. Börner , A. Friesen, F. Schappacher, M. Winter – 08./09.03.2018 – Petten
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Factors influencing the thermal stability of li-ion ... · Markus Börner | 08.03.2018 | Workshop -Thermal Propagation Page 5 M. Börner et al., J Power Sources 342 (2017) 382-395
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Factors Influencing the Thermal Stability of Lithium Ion Batteries-
From Active Materials to State-of-Charge and Degradation
JRC Exploratory Research Workshop – Safer Li-Ion Batteries by Preventing Thermal Propagation? M. Börner, A. Friesen, F. Schappacher, M. Winter – 08./09.03.2018 – Petten
Factors Influencing the Thermal Stability of Lithium Ion Batteries - From Active Materials to State-of-Charge and Degradation
M. Börner et al., J Power Sources 342 (2017) 382-395A. Friesen et al., J Power Sources 342 (2017) 88-97X. Mönnighoff et al., J Power Sources 352 (2017) 56-63
Commercial 18650 cell
Cathode LiNi0.5Co0.2Mn0.3O2
Anode Graphite
Separator PE
Electrolyte solvents DMC, EC, PC
Electrolyte additives FEC, PS, SN
Nominal Capacity 2.2 Ah
Charge4.2 V
CCCV - 1C; < C/20
Discharge2.5 V
CC - 1C
20°C Strong capacity fading after 100 cycles (<400 cycles to an SOH* of 70%)
45°C Almost linear capacity fading indicates the formation of an effective SEI and homogeneous degradation effects(>1100 cycles to an SOH* of 70%)
* State of health: SOH
Reference Insufficient formation by cell manufacturer 20°C Deposition of “mossy” metallic lithium 45°C Formation of an effective SEI confirmed
• Onset of exothermic reactions is determined by the anode side
Deposition of metallic lithium on the anode surface should be prevented
Effective and thermally stable SEI is key for a safe LIB
• High reactivity of the cathode in presence of electrolyte dominates the kinetics during thermal runaway
Layered and spinel-type electrodes exhibit a decreased thermal stability in the charged state
The presence of nickel largely reduces the thermal stability of positive active materials (especially in the charged state; Ni4+) independent of the structure (layered/spinel)
An increasing nickel content in the NCM structure intrinsically reduces the thermal stability
Overall, aging effects have a larger influence on the thermal stability of layered transition metal oxides like NCM compared to spinel-type or olivine-type active materials