Smart batteries enabled by implanted flexible sensors

Growing demand for high energy storage density is driving lithium-ion batteries (LIBs) to increasingly large design sizes, and the enhancement of battery charging and discharging ability is calling for a high-safety charging strategy, which places an ever-higher requirement on accurate management of battery operating conditions. Currently, the advanced battery management systems (BMSs) have moved forward, but rely on complex algorithms, and the novel hardware units require development to acquire the internal state of the battery, for example implanted sensors. Access to the internal information of the working batteries will greatly improve the accuracy of state estimation and further enhance the management performance. Implanted sensors will directly touch the internal environment of a cell and obtain the corresponding parameters at a temporal and spatial resolution level to achieve high accuracy of state estimation. The implanted sensors will empower the "smart battery" and contribute to smart BMSs in the future. Herein, we summarize the development of smart batteries based on multidimensional sensors. We outline the emerging cell-level flexible sensors, the possible flexible electronics technology, and the battery management strategies based on multiple sensors. The design principle, integration method and special issues in fabrication are also discussed. Special attention is given to the important role, major challenges and future directions of implantable sensors for smart batteries. We anticipate that these insights will add to the promotion of smart batteries in academic research and industrial applications.