Piezoresistive Free-standing Microfiber Strain Sensor for High-resolution Battery Thickness Monitoring.

Highly sensitive microfiber strain sensors are promising for the detection of mechanical deformations in applications where limited space is available. In particular for in-situ battery thickness monitoring where high resolution and low detection limit are key requirements. Herein, we present the realization of a highly sensitive strain sensor for in-situ Li-ion battery thickness monitoring. The compliant fiber-shaped sensor is fabricated by an upscalable wet-spinning method employing a composite of microspherical core-shell conductive particles embedded in an elastomer. The electrical resistance of the sensor changes under applied strain, exhibiting a high strain sensitivity and extremely low strain detection limit of 0.00005 with high durability of 10000 cycles. To demonstrate the accuracy and ease of applicability of our sensor, the real-time thickness change of a Li-ion battery pouch cell is monitored during the charge and discharge cycles. Our work introduces a promising approach with the least material complexity for soft microfiber strain gauges. This article is protected by copyright. All rights reserved.