LiFePO 4 particle conductive composite strategies for improving cathode rate capability

Abstract

Lithium iron phosphate (LFP) cathodes are one of the most promising candidates to find application in hybrid electric vehicle energy storage system. For this reason advances in the performance of its theoretical capacity at high charge/discharge rates is under continuous development. Most used strategies to improve power performance are carbon coating and the addition of a conductive polymer, such as poly(3,4-ethylenedioxythiophene) [PEDOT]. The data obtained from impedance analysis show that these strategies not only improve the charge transfer but also favor the lithiation/delithiation processes in the phosphate matrix. Furthermore, PEDOT is capable to reduce the resistances of charge transfer and lithiation reaction inside the phosphate matrix by one order of magnitude in comparison with those achieved with the carbon coating strategy. In this study, the most effective strategy has been the addition of PEDOT by a blending method, resulting in a specific capacity of 130 mA h g LFP -1 at 2C.2

New functional conducting poly-3,4-ethylenedioxythiopene:polystyrene sulfonate/carboxymethylcellulose binder for improvement of capacity of LiFePO4-based cathode materials

“…Conducting polyelectrolyte dispersion PEDOT:PSS, which can act both as electronconducting additive and as a binder, turned out especially attractive, providing enhanced electrochemical performance of the electrodes [16][17]19]. In the most cases of proposed 1 Corresponding author.…”

“…Additional improvement of the electrochemical properties of LFP-based cathode materials with the use of conducting polymer coatings [9][10][11][12][13][14][15][16][17][18][19][20], and in particular, poly-3,4-ethylenedioxythiopene [12,[13][14][15] was proposed.…”

“…This complex water-based additive, where PEDOT:PSS played dual role as conductive and binder additive [16,17,19] and carboxymethylcellulose (CMC) as additional binder [21] and thickening agent with good ionic conductivity [22]. It is more consistent with aqueous dispersion of PEDOT:PSS than the usual binder PVDF, that was used in [18].…”

New approaches to the lithiation kinetics in reaction-limited battery electrodes through electrochemical impedance spectroscopy

“…In this model, sf R and sf C yield an arc related to the resistance and capacity of the Li ions rapid diffusion through the solid film (SF) formed at the cathode-electrolyte interface due to the decomposition reactions during lithiation-delithiation processes. 13,14 The use of the model in Figure 1f is adopted here as a phenomenological approach in the case of multiparticle electrodes even with rate-limiting mechanism dominated by ion diffusion. It allows extracting the influence of hindrance processes and compare electrode performances.…”

Review—Recent Research Progress in Surface Modification of LiFePO4Cathode Materials

“…Meanwhile, PEDOT possesses an excellent electrochemical stability. [95][96][97] Vicente et al 98 synthesized the LiFePO 4 composite cathode material, coated with a composite polymer of PEDOT as an electronic conductive carbon, and followed by polystyrene sulfonate (PSS) doping. PEDOT can reduce the resistance of charge transfer and favor the lithiation/delithiation reaction inside the phosphate matrix by one order of magnitude.…”