The Effect of Sintering Temperature on Electronic Conductivity of LiFeGdPO<sub>4</sub>/C as a Lithium-Ion Battery Cathode

Abstract

Lithium ion batteries with LiFePO4 cathode have become the focus of research because they are eco-friendly, stable, high average voltage (3.5 V), and high theoretical capacity (170 mAh/g). However, LiFePO4 has disadvantages such as low electrical conductivity (~10-9 S/cm) and low lithium ion diffusion coefficient (~10-14-10-15 cm2/s) that can inhibit its application as a lithium ion battery cathode material. To increase the electronic conductivity of LiFePO4, it can be done by adding carbon as a coating material, then doping gadolinium metal ions because it has a radius similar to Fe, and increasing sintering temperature. Optimizing the sintering temperature can control particle growth and research was study the sintering temperature of the electronic conductivity of LiFeGdPO4/C and obtain the optimum sintering temperature at LiFeGdPO4/C. The carbothermal reduction method used in synthesis, with a variation of sintering temperature of 800°C, 830°C, 850°C, 870°C, and 900°C using reagents LiH2PO4, Fe2O3, Gd2O3, and carbon black. Furthermore the samples were characterized using XRD, SEM-EDS, and four-point probes. The results of the study were expected to increase the conductivity of LiFePO4. The results show the effect of sintering temperature can increase the electronic conductivity of LiFeGdPO4/C. Samples with a sintering temperature 850°C have the highest conductivity among all temperature variations with a value of 1.11 × 10-5 S cm-1.