Effect of compositional modification of (Ni_xCo_yMn_3−x–y) O₄ on electrical properties for the application to temperature sensor

(Ni_xCo_yMn_3−x–y)O₄ (NCM) spinel oxides have been widely utilized for industrial applications including the temperature sensor in the battery management system of electric vehicles. Accordingly, various engineering strategies such as the substitution of different elements, and control of heat treatment have been introduced to modify NCM to satisfy the specific properties of the temperature sensor. Herein, we report the compositional modification of the NCM influence on electrical properties with temperature for the application of temperature sensors. Our results demonstrate that the crystal structure of the NCM is determined by the Mn/Co ratio, which is related to electrical resistance and sensitivity (B value). Also, we investigate the effect of vanadium pentoxide (V₂O₅) on the sintering behavior of the NCM, which results in lower sintering temperatures. Representative NCM pellet with the chemical composition of Ni_0.31Co_0.93Mn_1.76O₄ shows negative temperature coefficient (NTC) properties with electrical resistance and B value as 25,539 Ω and 3921 K, respectively, which is suitable for industrial-level temperature sensor. This study provides a deeper understanding of how the manipulation of transition metal ratios can tailor the properties of spinel oxides for temperature sensing applications.