Analysis of thermal and electrical conductivity properties of Al substitution LiHf2(PO4)3 chemical solid electrolyte

Abstract

Lithium ion conducting solid electrolytes, lithium aluminum hafnium phosphate (Li 1+x Hf 2−x Al x (PO 4) 3 , x = 0-0.75) are prepared via solid state synthesis technique. Thermo-gravimetric analysis indicates that the thermal decomposition and thermal stability of the reaction mixture is generally affected by a high content of x value substitution. It can be observed that as x content or aluminum substitution increases, the thermal decomposition and thermal stability increase which leads to the sample formation towards higher temperature. For X-ray diffraction analysis, the Rietveld refinement analysis indicates the presence of different types of secondary phases as aluminum content increases. Single phase of lithium hafnium phosphate (LiHf 2 (PO 4) 3) is only achievable in the absence of any aluminum substitution. Furthermore, for the lithium ionic conductivity, the findings indicate that conductivity increases with increase in x substitution in lithium aluminum hafnium phosphate. The highest AC conductivity is observable in the sample with composition x = 0.25 of about 2.5 × 10 −3 Ω −1 m −1 with low activation energy 0.36 eV. The present studies recommend the sample with composition x = 0.25 (Li 1.25 Hf 1.75 Al 0.25 (PO 4) 3) to be a future solid electrolyte material for battery applications.

Recent Advances in Conduction Mechanisms, Synthesis Methods, and Improvement Strategies for Li1+xAlxTi2−x(PO4)3 Solid Electrolyte for All‐Solid‐State Lithium Batteries

“…investigated the effect of Al substitution in LHP, and the results show that Li 1.25 Al 0.25 Hf 1.75 (PO 4 ) 3 has a high Li ionic conductivity of 2.5 × 10 −3 S cm −1 at RT. [ 54 ] Despite this, it should be noted that LHP undergoes a phase transition from rhombohedral to trigonal when the temperature is reduced to 0 °C. The strong delocalization of Li ions is detected at the M1 and M2 sites, that severely limits the practical use of the LHP.…”