Design and Batch Preparation of a High-Performance Temperature Sensor for New Energy Vehicles Using Platinum Film

With the rise of the new energy industry, the number of new energy vehicles is increasing year by year, however, the thermal runaway of lithium-ion (Li-ion) batteries is a tough problem. As a key component of the battery management system (BMS), a high-performance, interchangeable, and low-cost temperature sensor is essential to improve the safety of power batteries in new energy vehicles. In this article, a batch of platinum (Pt) resistance temperature sensors with ten kinds of line widths were prepared by using micro-electro-mechanical system (MEMS) batch microfabricating technology. After tests, these batch-prepared temperature sensors possess high performance, small size, and low cost. They showed extremely high linearity of resistance-temperature curves ( ${R}^{{2}} >$ 0.9999) and superior accuracy ( $< 0.3~^{\circ }\text{C}$ ). Besides, the effects that came from MEMS technology were explored. The batch of temperature sensors showed excellent consistency of linearity and temperature coefficient of resistance (TCR), 99.99% and 98.89%, respectively. Furthermore, the temperature sensor exhibited excellent repeatability and stability. The coefficient of variation (CV) is only 0.31% for five repeated calibration experiments and the max temperature deviation is below 0.05 °C in stability tests. Temperature sensors with $45~\mu \text{m}$ linewidth have the best interchangeability of all kinds with interchangeable temperature differences of less than 1.5 °C. All the results indicate that the batch microfabricated sensors are suitable for large-scale measurement requirements for Li-ion batteries in new energy vehicles.

I. Introduction

In recent years, with the rapid development of new energy vehicles [1], [2], [3], the number of reports that thermal runaway caused the fire and explosion of lithium-ion (Li-ion) batteries is increasing. In the protection of Li-ion batteries, a battery management system (BMS) plays the most important role during the working of Li-ion batteries, where a high-performance temperature sensor is an essential part to improve safety [4], [5], [6], [7], [8], [9], [10]. Typically, a power battery pack in vehicles is consisted of about 100 Li-ion cells [11]. As the closest part to the battery pack and the onboard component, the temperature sensor with high stability and interchangeability is favored. But a single temperature sensor is insufficient to fully monitor the “huge” battery pack. When the number of sensors increases, the temperature detection of Li-ion batteries will be more accurate. If we want to increase the number, their size should be reduced. In this era of rapid development of integrated circuits, miniaturization has become the main development trend of most electronic components [12]. At the same time, low cost is the first choice for factory manufacture. Therefore, a high-performance, small-size, low-cost temperature sensor will have a very broad market.