2026-07-01 ミシガン大学
＜関連情報＞
- https://news.umich.edu/smarter-diagnostics-could-extend-the-lives-of-silicon-ev-batteries/
- https://www.cell.com/joule/fulltext/S2542-4351(26)00215-1
- https://www.sciencedirect.com/science/article/pii/S2590116825000232
耐久性の高い高エネルギー密度バッテリー向けに、オンボード材料診断によるシリコン焼損管理を行う Managing silicon burn-out via onboard material diagnostics for durable high-energy density batteries
Zhiwen Wan ∙ Andrew Weng ∙ Sravan Pannala ∙ … ∙ Gregory J. Offer ∙ Jason B. Siegel ∙ Anna G. Stefanopoulou
Joule Published:June 23, 2026
DOI:https://doi.org/10.1016/j.joule.2026.102531
Highlights
- Onboard diagnostics quantify Si capacity loss and effective OCP evolution
- Si-dominant SoC windows shift strongly with degradation pathway
- Aging-aware thermal control can double cycle life without limiting capacity
Summary
Silicon-graphite (Si/Gr) anodes increase battery energy density, but rapid Si “burn-out” limits lifetime. Yet, battery management systems lack effective tools to diagnose Si aging beyond capacity loss and to manage its degradation during operation. Here, we develop a diagnostic framework that jointly estimates material-specific health and degradation-induced Si open-circuit potential deformation from constant-current charge data. The framework tracks the transition state-of-charge (SoC) below which Si dominates, revealing pathway-dependent Si utilization shifts: from 48% fresh to 73% with lithium loss but 33% with active-Si loss. Transition SoC error remains below 3% up to an effective 0.3C, and error bounds across sampling and charge windows support onboard use. Guided by the finding that elevated temperature improves Si capacity retention in our cells, we propose adaptive thermal management that warms the cell during Si-dominant operation and cools it otherwise, projecting an approximately doubled cycle life without limiting capacity access.
シリコン/グラファイト負極を用いたリチウムイオン電池の劣化と膨張：予圧、温度、Cレート、充電状態範囲の影響 Degradation and expansion of lithium-ion batteries with silicon/graphite anodes: Impact of pretension, temperature, C-rate and state-of-charge window
Zhiwen Wan, Sravan Pannala, Charles Solbrig, Taylor R. Garrick, Anna G. Stefanopoulou, Jason B. Siegel
eTransportation Available online: 19 March 2025
DOI:https://doi.org/10.1016/j.etran.2025.100416
Highlights
- High pressure (34–172 kPa) reduced resistance/expansion with limited capacity impact.
- Cycling at 45°C extended battery life but caused more early-life resistance growth.
- Irreversible expansion closely aligned with resistance patterns at 25°C and 0°C.
- ICA/DVA identified LLI pre-knee and a combined LLI, LAM-Anode (Si) effect post-knee.
- EIS revealed SEI resistance as the dominant contributor to kinetic degradation.
Abstract
Lithium-ion batteries with silicon/graphite (Si/Gr) anodes achieve higher energy densities but face challenges such as rapid capacity fade, resistance growth, and complex expansion behavior under various cycling conditions. This study systematically addresses these challenges through a comprehensive test matrix to investigate the effects of 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. Increasing the applied pressure between 34 and 172 kPa reduced both reversible and irreversible expansion per cycle, as well as resistance growth over time, without significantly impacting capacity fade. Electrochemical Impedance Spectroscopy (EIS) confirmed that increased pressure lowered initial solution resistance and mitigated the further growth of the solution and solid electrolyte interphase (SEI) resistance. Elevated temperature (45°C) extended battery cycle life despite an initial increase in resistance. The lifetime impedance increase under 45°C was dominated by SEI resistance. Consistent with prior studies, operating in a narrow SoC window at high SoC minimized capacity loss. Additionally, charge rates up to 2C had a limited effect on the overall degradation trends. Incremental capacity analysis (ICA) and differential voltage analysis (DVA) identified lithium inventory loss (LLI) as the primary cause of pre-knee degradation, whereas post-knee degradation resulted from a combination of LLI and anode-active material loss, particularly silicon. The deeper understanding of degradation mechanisms in batteries with Si/Gr anodes provided by this work enables the optimal packaging design and selection of operating conditions for the battery management system to extend battery cycle life.
