Hysteresis in electrochemical systems

Abstract

Hysteresis is a phenomenon that pervades both the physical and social sciences. While commonly associated with magnetism, it also occurs in a wide variety of other materials, including ferroelectrics and shape memory alloys.Hysteresis emerges when a particular property has a history dependence. It is exploited in microelectronic memory, logic, and neuromorphic devices. In electrochemical systems, such as Li-ion batteries, hysteresis is undesirable as it leads to energy losses during each round trip charge-discharge cycle. Unfortunately, many new battery concepts that promise significant increases in energy density, including those that rely on displacement and conversion reactions, or on anion-redox mechanisms, suffer from severe hysteresis that prevents their commercialization. This article surveys different forms of hysteresis in electrochemical systems with a focus on Li-ion batteries and establishes thermodynamic and kinetic principles with which to understand and rationalize electrochemical hysteresis. The ability to control hysteresis in rechargeable batteries will enable the implementation of promising electrode chemistries. It will also open the door to many new device applications. As onchip batteries become more prominent, new possibilities will emerge to incorporate them not only as local energy sources but also as active components of new device concepts that exploit electrochemical hysteresis.

A Thermodynamic Model for the Insertion Electrochemistry of Battery Cathodes

“…[1,2] At a macroscopic level, this problem manifests in energy losses during a charging-discharging cycle. This phenomenon could be a consequence of charge-discharge hysteresis which is an inherent feature of not only Ni-based cathodes, [3][4][5] but also many other battery materials [6][7][8] including the prototypical LiFe 2 O 4 . [9,10] Charge-discharge hysteresis in batteries has recently attracted an increasing attention but is yet poorly understood, because contrary to soluble redox species, the electrochemical thermodynamic and kinetics of solid redox systems have not been developed as much.…”

Entering Voltage Hysteresis in Phase‐Separating Materials: Revealing the Electrochemical Signature of the Intraparticle Phase‐Separated State

“…In the context of this study, it is important to distinguish between the hysteretic effects [ 17 ] of thermodynamic origin and different types of overpotentials. Overpotentials have a kinetic origin and can be minimized, for example, by systematically reducing the charge or discharge rate, [ 17 ] and eventually eliminated in the asymptotic limit of exceedingly slow charge and discharge currents. This does not apply to hysteretic effects of thermodynamic origin, which cannot be avoided, except in very rare cases.…”

A Coacervate-Based Mixed-Conducting Binder for High-Power, High-Energy Batteries

“…GITT results indicate that the CPC binder reduces the kinetic barriers to charge transport during charge and discharge. GITT is a powerful technique to separate kinetic and thermodynamic overpotentials. − As mentioned earlier, kinetic overpotentials or polarization results in a dissipative form of voltage hysteresis that can be minimized by systematically reducing the rate with which the battery is charged and discharged . In a GITT experiment, the kinetic overpotential is the difference between the potential during the constant current pulse and the equilibrium potential after a sufficiently long rest period when no current is flowing through the circuit (see Figure a inset).…”

“…The higher rate capability of the CPC-cell is consistent with its reduced polarization (Figure c,d), indicating that the CPC binder improves charge transport kinetics within the composite electrode. Cell polarization is a form of electrochemical hysteresis (sometimes called dissipative hysteresis) that results from sluggish kinetic processes as opposed to other, thermodynamic mechanisms of hysteresis, including first-order phase transitions, displacement and conversion reactions, reaction path hysteresis, etc . Polarization leads to an overpotential, i.e., a deviation of the potential from the true equilibrium potential of the redox reaction at playhere, Li extraction from LFP on charge, Li reinsertion into LFP on dischargeand therefore to a voltage hysteresis between the charge and discharge processes.…”