(Invited) High Energy Density and Ecofriendly Lithium-Ion Battery with Operando Monitoring

Abstract

In addition to recent worldwide renewable energy commitments, advances in electrical vehicle technologies, flexible electronics, smart wearable devices, and internet of things, have contributed to the increasing demand for batteries with a wide range of electrochemical and electromechanical properties. In response, the battery industry has launched intensive research and development efforts in search for new materials, technologies, and concepts. However, these rapid developments give rise to a growing concern on the impact of this industry on Nature. Hence, the rapidly growing battery market demands resolutions for both energy and waste-management challenges in anticipation of about two million metric tons of annual battery waste generated globally. One way to resolve this energy and environment dilemma is by revising the conventional battery architecture to assure both high energy density and efficient recyclability aiming at circular economy. Within this strategy we fabricated self-standing composite electrodes that eliminated electrochemically inactive metal current collectors and binders from the Li-ion battery architecture, increasing energy density up to 40%. These electrodes were prepared via in situ mixing of as-grown single-wall carbon nanotubes (SWNTs) with aerosolized electrode active materials in ratios (≥0.25 wt%) that provide adequate electrical conductivity and mechanical robustness under stretching (≤15%), bending (d≥2 mm) and twisting (θ~180o) cycles. Remarkably, the resultant SWNT scaffold in composite electrodes operates as an intrinsic piezoresistive strain sensor (Gauge Factor ~6.2) that for the first time allows in situ/operando self-monitoring of battery structural health without interfering with electrochemical reactions. Moreover, the developed solution-free fabrication method eliminates hazardous, toxic, and environmentally harmful components and procedures from the electrode production line and allows their recycling by simple sonication and recovering of the active materials. In addition, the absence of current collector foils and binder allows for easy recycling and recovery of the constituent materials by using physical separation methods. These new features not only reduce consumption of the natural resources but also promote the eco-friendly circular economy for batteries.