Open Access

ARTICLE

Mechanical Modelling of Positive Electrode in All-Solid-State Battery Cells

Vilim Cvenk¹, Filip Maletić¹, Simon Erker², Danijel Pavković^3,*, Mihael Cipek³
1 AVL-AST d.o.o., Zagreb, Croatia
2 AVL List GmbH, Graz, Austria
3 Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Zagreb, Croatia
* Corresponding Author: Danijel Pavković. Email:
(This article belongs to the Special Issue: Selected Papers from the SDEWES 2025 Conference on Sustainable Development of Energy, Water and Environment Systems)

Energy Engineering https://doi.org/10.32604/ee.2026.077842

Received 18 December 2025; Accepted 17 March 2026; Published online 07 April 2026

Abstract

All-solid-state lithium-based batteries represent a critical evolution in energy storage, offering enhanced safety, higher energy density, and superior fast-charging capabilities. However, the integration of solid-state electrolytes introduces complex mechanical interactions at the electrode-electrolyte interface that significantly impact performance and longevity. This study introduces a cyclic plastic hardening model for ceramic electrolytes, moving beyond traditional brittle or linear-elastic assumptions. It presents a Finite Element Method (FEM) analysis of a positive electrode representative volume element (RVE), consisting of spherical Nickel-Manganese-Cobalt (NMC811) active material particles embedded in an Li₇La₃Zr₂O₁₂ (LLZO) solid-state electrolyte matrix, with Gaussian-distribution of particle sizes aimed to capture the stochastic heterogeneity of electrode microstructures. The simulation results illustrate the volumetric expansion and contraction of active material during lithiation and de-lithiation (electrochemical loading) cycles using a thermal expansion analogy. Due to the scarcity of cyclic plasticity data for ceramic electrolytes, the plastic hardening behavior of LLZO is approximated using a proxy material model (SiMo5 steel at 700°C) to qualitatively capture strain hardening effects. The study analyzes stress distribution, volumetric deformation, and contact evolution over five charge-discharge cycles under a uniform assembly external pressure of 10 MPa. Results indicate progressive strain hardening in the solid electrolyte, characterized by increasing tensile stresses and stabilizing volumetric deformation. Furthermore, the analysis reveals cyclic contact loss during de-lithiation, which poses risks for increased interfacial resistance. These findings provide theoretical insights into the mechanical degradation mechanisms of ASSBs, emphasizing the key role of stack pressure and material hardening in their long-term stability.

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Graphical Abstract

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Keywords

All-solid-state-batteries; solid-state electrolyte; porosity; stress in active material

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