Journal Club do Departamento de Física dos Materiais e Mecânica
Data do Evento:
06/11/2019 - 12:00
Quantifying the factors limiting rate performance in battery electrodes
Apresentação do artigo por Luiz Henrique de Melo dos Santos
06/11, 4ª feira, 12h10. Sala de Seminários José Roberto Leite (Ed. Alessandro Volta - bloco C)
One weakness of batteries is the rapid falloff in charge-storage capacity with increasing charge/discharge rate. Rate performance is related to the timescales associated with charge/ionic motion in both electrode and electrolyte. However, no general fittable model exists to link capacity-rate data to electrode/electrolyte properties. Here we demonstrate an equation which can fit capacity versus rate data, outputting three parameters which fully describe rate performance. Most important is the characteristic time associated with charge/discharge which can be linked by a second equation to physical electrode/electrolyte parameters via various rate-limiting processes. We fit these equations to ~200 data sets, deriving parameters such as diffusion coefficients or electrolyte conductivities. It is possible to show which rate-limiting processes are dominant in a given situation, facilitating rational design and cell optimisation. In addition, this model predicts the upper speed limit for lithium/sodium ion batteries, yielding a value that is consistent with the fastest electrodes in the literature.