Meaning
Physics subdiscipline focusing on systems that are not in thermal, chemical or mechanical balance and are characterized by irreversible flows of energy and matter. Researchers apply non-equilibrium thermodynamics to understand the behavior of batteries during rapid charging where gradients of temperature and concentration are extreme. This framework provides the tools to calculate the energy lost as heat and the rate of degradation in active materials.
Energy Dissipation
Irreversibility within a system leads to the production of entropy and the loss of useful work. In the context of non-equilibrium thermodynamics, the heat generated by ion movement and chemical reactions is a measure of this inefficiency. Large gradients in the battery cell cause local overheating, which can trigger side reactions that shorten the life of the device.
Identifying the sources of these losses allows engineers to design better thermal management systems. Minimizing energy dissipation is the primary strategy for improving the round trip efficiency of large scale storage.
Transport Rate
Movement of ions and electrons is driven by forces that are proportional to the gradients of chemical potential and temperature. Within the field of non-equilibrium thermodynamics, these flows are coupled, meaning a temperature gradient can drive a concentration gradient. This coupling explains the migration of lithium ions toward hot spots in a cell, which can cause local plating and short circuits.
Accurate modeling of these transport phenomena is required to predict the performance of the battery under high load. These models guide the selection of electrolytes with high ionic conductivity and stability.
System Limit
Stability of a material is often defined by how far it can be pushed from its equilibrium state before it fails. Non-equilibrium thermodynamics sets the boundaries for safe operation by identifying the points where the system might undergo a phase change or a runaway reaction. Monitoring the fluctuations in voltage and temperature provides early warning of these events.
Most commercial safety protocols are based on the limits established through these physical laws. By staying within the stable regime, the operator ensures the longevity of the energy storage asset.
