In launch vehicles, lithium-ion batteries are used to provide power to the avionics system and other key systems, releasing large amounts of power quickly to achieve the electrical power requirements of the whole system. To realize the reliable, safe, and efficient use of lithium-ion batteries, it is necessary to establish an accurate battery model. Addressing the challenge of requiring extensive prior knowledge to establish the electrochemical model of a lithium-ion battery, this article presents a novel method of constructing electrochemical model using less prior knowledge. By simplifying the electrochemical model without compromising its accuracy, it plays a positive role in promoting the electrochemical model of lithium-ion batteries. To validate the accuracy of the model developed in this article, a comparison is conducted with the widely used equivalent circuit model, and experimental data under the Dynamic Stress Test (DST) of lithium-ion batteries are employed for verification. The results of the validation demonstrate that both models effectively capture the dynamic behavior of lithium-ion batteries. The maximum errors for the two models are 0.239 V and 0.267 V, while the average errors are 0.0093 V and 0.0312 V, respectively. Finally, the electrochemical model proposed in this article is fully verified with simulation.