Abstract
Silicon anodes offer exceptional energy density for solid-state batteries (SSBs), but their commercial viability is limited by mechanical degradation, unstable SEI formation, and interfacial failure due to severe volume changes [1]. In this study, we systematically evaluate microcrystalline, nanocrystalline, and nanoporous Si (np-Si) anodes, each integrated with uniformly fine Li₆PS₅Cl (LPSCl) solid electrolyte particles (~1 μm) to fabricate dense, homogeneous composite electrodes. The narrow particle size distribution (PSD) of LPSCl enhances particle packing, improves interfacial contact, and minimizes void formation—boosting ionic conductivity and cohesion [2]. Additionally, 8 μm LPSCl powder with narrow PSD was used to create high-density separator layers, reducing grain boundary resistance and interfacial impedance [3][4]. Among the Si morphologies, np-Si shows superior cycling performance under limited lithiation due to its internal buffering capability, accommodating expansion while preserving structure. Cryogenic ion milling and SEM imaging reveal that internal pores remain collapse-free, enabling uniform lithiation and stress mitigation. Stable SEI forms only at interfaces, leaving interior Si largely SEI-free. Operando XRD monitored strain evolution, showing that lithiation control effectively suppresses irreversible phase transitions and strain-induced degradation. These principles were scaled from coin cells to 8 × 6 cm² pouch cells, achieving 190 mAh/g in the initial cycle and operating at 1 MPa, demonstrating a scalable, EV-relevant architecture ready for module-level integration.
References:
[1] Zhao, Xuyang, et al. "Development of Si-Based Anodes for All-Solid-State Li-Ion Batteries." Coatings 14.5 (2024): 608.
[2] Huo, Hanyu, et al. "Decoupling the Effects of Interface Chemical Degradation and Mechanical Cracking in Solid‐State Batteries with Silicon Electrode." Advanced Materials 37.7 (2025): 2415006.
[3] Chen, Yu-Ting, et al. "Fabrication of high-quality thin solid-state electrolyte films assisted by machine learning." ACS Energy Letters 6.4 (2021): 1639-1648.
[4] Wang, Yixian, et al. "Mechanical Milling–Induced Microstructure Changes in Argyrodite LPSCl Solid‐State Electrolyte Critically Affect Electrochemical Stability." Advanced Energy Materials 14.23 (2024): 2304530.