Lithium-ion batteries have become a key technology in our everyday lives, and great interest has grown during the past decade towards new materials and new configurations of the cells. Solid state lithium batteries (SSBs) allow having higher energy density without compromising power and capacity, while assuring high safety at variable temperatures and good cycle stability. However, during the charge and discharge of these batteries there are significant volume changes in the electrodes that produce stress and strain effects on the solid materials. These effects can make layers separate and cracks to form in the battery materials, which reduces the potentially improved performance of these batteries. The present study investigates the causes of the mechanical degradation and aging in Solid State Batteries using tool that allows to determine under which operation conditions a SSB can operate without suffering these undesirable effects. This tool consists on a physics-based FEM model of a complete thin-film battery that would simulate volume expansion of the positive electrode material during cycling of the batteries and predict local stress/strain failure as a function of the state of charge of the cell. The model follows a built- in approach in which the interface geometry increases in complexity gradually in three main steps (planar thin film, 3D pillar-array thin film [2], and irregular-interface porous-type cell), and it is validated experimentally at each step. In the first step, planar thin films (Li metal / LiPON / LMO) are constructed in collaboration with IMEC Research Center. Electrochemical characterization of these planar thin films is performed using the in-house developed Odd Random Phase Electrochemical Impedance Spectroscopy setup (ORP-EIS) [3] in order to define the model input parameters. Further dilatation measurements are performed on the planar thin films in order to quantify volume changes in the cells during charge and discharge and validate the model results. In further steps, the simulation of volume changes during charge and discharge is performed in geometrically modified thin-film interfaces to determine the relation between interface geometry and stress formation in the solid materials during charge and discharge.
Original languageEnglish
Publication statusPublished - 4 Aug 2019
EventThe 70th Annual Meeting of the International Society of Electrochemistry: Electrochemistry: Linking Resources to Sustainable Development - Durban International Convention Centre, Durban, South Africa
Duration: 4 Aug 20199 Aug 2019
https://annual70.ise-online.org/

Conference

ConferenceThe 70th Annual Meeting of the International Society of Electrochemistry
CountrySouth Africa
CityDurban
Period4/08/199/08/19
Internet address

ID: 48921264