**Abstract**

Most of the work has been done on the optical properties of the rare earth doped CePO4, so there are few studies on the effect of metal ion doping on CePO4. The doping improves the properties of the compounds and can lead to new properties. **It is the first time, that multi- ionic doping process is used in the CePO4 matrix, in order to improve the ionic conductivity and the electrochemical stability.** The low percentage of (Cd2+, Li+ ), Cr3+, Bi3+ dopant affect the structure showing a weak decrease in the lattice parameters compared to the CePO4. Impedance spectroscopy analysis was used to analyze the electrical behavior of samples as a function of frequency at different temperatures. The total electrical conductivity plots obtained from impedance spectra shows an increase of the total conductivity as Li, Crcontent increases. The determined energy gap values decrease with increasingly Li<sup>+</sup> , Cr3+ and Bi3+ doping content. Electrochemical tests showed an improved capacity when increasing the Li<sup>+</sup> , Cr3+ and Bi3+ content and a stable cycling performance.

**Keywords:** phosphate materials, doping, optical properties, impedance spectroscopy, electrochemical properties
