Analysis of Redox Additive‐Based Overcharge Protection for Rechargeable Lithium Batteries

Abstract

The overcharge condition in secondary lithium batteries employing redox additives for overcharge protection, has been theoretically analyzed in terms of a finite linear diffusion model. The analysis leads to expressions relating the steady-state overcharge current density and cell voltage to the concentration, diffusion coefficient, standard reduction potential of the redox couple, and interelectrode distance. The model permits the estimation of the maximum permissible overcharge rate for any chosen set of system conditions. Digital simulation of the overcharge experiment leads to numerical representation of the potential transients, and estimate of the influence of diffusion coefficient and interelectrode distance on the transient attainment of the steady state during overcharge. The model has been experimentally verified using 1, l'-dimethylferrocene as a redox additive. The analysis of the experimental results in terms of the theory allows the calculation of the diffusion coefficient and the formal potential of the redox couple. The model and the theoretical results may be exploited in the design and optimization of overcharge protection by the redox additive approach.

Synthesis and characterization of an electroactive ionic liquid based on the ferrocenylsulfonyl(trifluoromethylsulfonyl)imide anion

“…5B). The diffusion coefficient is a key factor used to evaluate the maximum current that the redox shuttle in LIB can carry [47]. These values represent a diffusion rate which is roughly 50% of Fc, which is due to the larger radius of the FcNTf.…”

Electrochemical studies of ferrocene in a lithium ion conducting organic carbonate electrolyte

“…In this work, we investigated ferrocene redox chemistry in 1 M LiPF 6 /1:1 EC:EMC which is a typical liquid electrolyte used in Li-ion batteries. Another motivation for our study is that these ferrocene experiments can serve as models for investigating the redox chemistry of other chemical shuttle reagents used for overcharge protection of rechargeable Li-ion batteries [16][17][18][19]. We report the mass transport and kinetic parameters of the Fc 0 /Fc + couple in this prototypical Liion battery electrolyte.…”

Overcharge Protection for Rechargeable Lithium Batteries Using Electroactive Polymers

“…1 Overcharging of one or more cells within a high voltage multicell stack of the type required for vehicle traction can render the entire stack inoperative. External protection mechanisms that interrupt the charging process when a voltage, temperature, or internal pressure limit is reached are currently in use in consumer electronics battery packs, but these add weight, volume, and cost and may not allow the continued operation of a cell stack.…”