C-rate-dependent electrochemical, ionic and thermal behaviour of SnP₃/carbon nanocomposite anodes for potassium-ion batteries

Potassium-ion batteries (PIBs) are emerging as promising alternatives to lithium-ion systems owing to the natural abundance and low cost of potassium. However, their practical deployment at high charge–discharge rates is strongly limited by coupled ionic transport and thermal instabilities, particularly in alloy-type anodes. In this work, the C-rate-dependent electrochemical, ionic and thermal behaviour of a SnP₃/carbon nanocomposite anode for PIBs is systematically investigated using a multiphysics modelling framework validated by experimental cyclic voltammetry data. The model integrates charge conservation, K⁺ ion transport and heat generation to elucidate the interplay between reaction kinetics, concentration polarisation and thermal effects over C-rates ranging from 1 C to 4 C. The results reveal that increasing C-rate intensifies K⁺ depletion at the anode/electrolyte interface, leading to pronounced concentration gradients, elevated overpotentials and significant electrolyte conductivity degradation. At 4 C, severe ion starvation coincides with a temperature rise to 312.6 K, exceeding the thermal stability threshold of alloy-type anodes and indicating an increased risk of electrolyte decomposition and interfacial degradation. These findings highlight critical rate-limiting mechanisms in SnP₃/carbon anodes and underscore the importance of optimising electrode microstructure and electrolyte properties to enhance the high-rate capability and thermal resilience of potassium-ion batteries. Unlike previously reported studies that mainly focus on either electrochemical performance or thermal behavior independently, the proposed framework simultaneously captures ion transport limitations, electrolyte conductivity degradation, reaction kinetics, and heat generation. This integrated approach enables quantitative identification of the dominant degradation mechanisms governing high-rate operation and provides a predictive tool for the design of thermally stable, high-power potassium-ion batteries.

Hali tarjima qilinmagan