A Parity-Time-Symmetric Passive Wireless Sensor System for Simultaneous Temperature and Pressure Monitoring of Lithium-Ion Battery Safety

Authors:
Preprint
Publisher website
Google Scholar
Abstract
Lithium-ion batteries (LIBs) in energy storage systems often show rapid temperature and internal pressure increases before thermal runaway, posing safety risks. Thus, synchronized in-situ monitoring of both parameters is crucial for achieving early warning. However, conventional wired sensors lack pressure information, active wireless sensors need battery energy, and LC passive sensors suffer low quality factors and cross-coupling, limiting practical deployment. This article presents a battery-free, passive wireless sensor system based on Parity-Time (PT) symmetry for simultaneous temperature and pressure detection at the LIB explosion-proof valve. It consists of an active gain-side reader and a passive loss-side resonator. The loss side integrates a flexible capacitive temperature sensor. Both sides inductively couple through the same planar circular coil. Temperature modulates sensor capacitance, while pressure from the valve modulates the inter-coil coupling coefficient. The system decouples the two parameters using three zero-phase points of the S11 parameter. For practical deployment, a low-cost readout terminal based on a resistance bridge directional coupler is developed, with adaptive frequency tracking to replace the expensive vector network analyzer (VNA). Compared with a commercial VNA, maximum deviations are 5.21 dB and 7.23°. In single-parameter mode, maximum temperature and pressure sensitivities are 15.01 kHz/℃ and 95.66 kHz/kPa; in dual-parameter mode, maximum measurement errors are 1.93 ℃ and 1.99 kPa. The proposed system provides a deployable, low-cost solution for in-situ safety monitoring of lithium-ion energy storage systems.

This publication has 10 references indexed in Scilit: