Abstract
Lithium-Ion batteries are used in ever more demanding applications regarding operating range and safety requirements. This work presents a series of high-temperature abuse experiments on a nickel-manganese-cobalt oxide (NMC)/graphite lithium-ion battery cell, using advanced in-operando measurement techniques like fast impedance spectroscopy and ultrasonic waves, as well as strain-gauges. the presented results show, that by using these methods degradation effects at elevated temperature can be observed in real-time. These methods have the potential to be integrated into a battery management system in the future. Therefore they make it possible to achieve higher battery safety even under the most demanding operating conditions.
Highlights
Lithium-Ion batteries can nowadays be found in many applications, ranging from mobile computing devices over electric mobility up to multi-megawatt battery storage systems
The large volume change during Li alloying and de-alloying processes is problematic for stability of the anodic solid electrolyte interphase (SEI) and can lead to reduced cycle life of the battery cell [1]
Nickel rich NMC811 (Nickel/Manganese/Cobalt) materials have a specific capacity of up to 250 mAh/g [2], which is over 60 % increase compared to the conventional LiCoO2 cathode material. the resulting significant increase in energy density comes at the price of reduced thermal stability: the onset of exothermal decomposition of NMC811 is as low as 135 ◦C and can lead to a very strong oxygen release [3]
Summary
Lithium-Ion batteries can nowadays be found in many applications, ranging from mobile computing devices over electric mobility up to multi-megawatt battery storage systems. The ever increasing requirements on energy and power density of battery systems leads to the development of improved electrode materials. Alloy materials containing silicon are promising a greatly increased specific capacity compared to pure graphite. The resulting significant increase in energy density comes at the price of reduced thermal stability: the onset of exothermal decomposition of NMC811 is as low as 135 ◦C and can lead to a very strong oxygen release [3]. This reduced thermal stability means a significantly reduced safety margin, compared to more stable materials with lower Ni content
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