Highly improving the electrochemical performance of LiFePO₄ modified by metal phthalocyanines as cathode materials

Abstract

Abstract

Metal tetrabromophthalocyanines mediate the structure and electrochemical performance of lithium iron phosphate as cathode materials for lithium-ion batteries

“…2g and h, respectively. Compared with pure LFP, amorphous carbon is successfully formed and effectively surrounds the LFP-6 particles, resulting in faster Li + diffusion and more enhanced electrochemical performance [16]. XRD patterns of samples are given in Fig.…”

“…Pure LiFePO 4 (LFP) was prepared under the same conditions without MPcTb. More details were referred to the literature [16]. The as-prepared samples LiFe 1 − x M x PO 4 /C using MPcTb (M = Mn, Fe, Co, Ni, Cu, Zn) additives are termed as LFP-1, LFP-2, LFP-3, LFP-4, LFP-5 and LFP-6, respectively.…”

“…The obtained products possess more strengthened electrochemical performance than that in the literature [16]. The structural characterization has been achieved by XRD and SEM.…”

“…Remarkably, combination of conductive carbon coating and metal doping has been proved to be an effective way to improve the specific capacity and rate capability because the transport lengths of both electrons and ions would be shortened by the carbon layer and the space for intercalation/deintercalation of Li + would be enlarged due to the crystal lattice distortion by doped metal [13][14][15]. Our previous work proved that the two factors could be provided simultaneously by using metal phthalocyanines (MPcs) as additives to mediate the structure and electrochemical performance of LiFePO 4 , which can simplify the preparation process of the composites [16]. The excellent characteristics of MPcs, such as oxidation-reduction activity, great stability, non-toxicity and low cost, drive them to be cathode replacing materials of lithium-ion batteries [17,18].…”

“…Thus the electrochemical properties of LiFePO 4 can be improved by decorating with MPcs. In the light of reference [16], metal phthalocyanines (MPc) and metal tetrasulfophthalocyanines (MPcTs) were used as additives to synthesize LiFe 1 − x M x PO 4 /C (x ≈ 0.0040) composites. It is found that MPcTs additives are optimized for the improvement of specific capacity, reversibility and cycling stability compared with MPc.…”