Lithium-Ion

Impact of Pretension, Temperature, CRate and State-of-Charge Window on Degradation of NMC|SiGr Si-Gr anodes achieve higher energy densities but can exhibit rapid capacity fade, resistance growth, and complex expansion behavior under various cycling conditions. Wan et al 2025 investigated the effects of stress factors like pressure, temperature, state-of-charge SoC) windows, and charge rates C-rates) on the evolution of expansion, resistance, and capacity behavior over the lifetime of the battery. Their findings on the optimal range(s) of these stress factors can guide battery pack and BMS design.

IMPACT OF PRESSURE & TEMPERATURE

IMPACT OF SOC WINDOW & CRATE

They also performed ICA and DVA and identified LLI and LLI LAMNE (particularly silicon) as the primary causes of pre-knee and post-knee degradation.

Moderate pretension forces 34172 kPa) are beneficial as they effectively reduce reversible expansion, irreversible expansion, and resistance growth with minimal impact on capacity fade. Elevated temperature 45 °C) extends NMC/Si-Gr cycle life despite an initial increase in resistance, and the lifetime impedance increase under 45 °C is dominated by SEI resistance. Operating in a narrow SoC window at high SoC minimizes capacity loss. Degradation is minimally impacted by charge rates up to 2C.

Source: Z. Wan et al., eTransportation 2025

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