The heat generation and themmal management issues of lithium-ion batteries during use have asignificant impaet on their performanee and safety, This paper experimentally investigates the thermalcharacteristies of prismatie lithium-ion batteries.A hybrid power pulse testing method was empleyed to measurethe changes in ohmie resistanee , polarization resistanee, and the eleetromotive foree temperature coeficientunder various ambient temperatures and discharge rates,The study analyzes the elfeets of ambient temperature,discharge rate ,and state of charge( $0C) on the battery’ s performance.Additionally ,a relationship between theinternal heat sourees of the battery and its $OC was fitted, and COMSOL, sotware was used to simulate thetemperature field of the battery under different ambient temperatures and diseharge rutes.The experimentalresults show that both the ohmie and polarization resistanees inerease with rising ambient temperature anddischarge rate ,and the changes in internal resistanee are closely related to the battery’'s state of charge.Thefindings of this study provide a theoretieal basis for battery thermal management and offer valuable insights forfuture battery design and safety evaluation.