Guest lecture by by Dr. Rachid Yazami (Nanyang Technological University)
August 12, 2019 @ 11:00 am – 1:00 pm
Topic: Innovative solutions for lithium ion batteries future development
Please register for the event here.
Date: August 12, Monday
Time: 11.00 am
The thermodynamics properties of a battery full reaction such as the Gibbs free energy ∆G, entropy ∆S and enthalpy ∆H can be determined by open‐circuit voltage measurements vs. temperature (OCV, E0 vs. T) at different states of charge of the cell (SOC) using equations:
It is found that ∆G, ∆S and ∆H vs. SOC profiles are characteristic of the battery’ chemistry and state of health (ageing, SOH). Also, a universal empiricallaw has been unveiled which governs all batteries tested, that is the state of charge is a linear function of entropy and enthalpy:
SOC = α + β ∆S + γ ∆H,
in which the α, β and γ variables depend on the cell’ chemistry and SOH.
Moreover, a minute analysis of the ∆S and ∆H profiles enables detection of early steps of internal short‐circuit formation, therefore reducing the risk ofthermal runaway and proving the state of safety (SOS).
We will also show how thermodynamics data help with the fast and adaptive charging of lithium ion batteries. Full charging below 1h using conventional methods such as constant current constant voltage and multi‐step constant current methods, CCCV and MSCC, respectively causes premature deterioration of the battery performances. Our non‐linear voltammetry method enables fast charging below 30 min without premature end oflife and safety issues.