Progress of Electrode Designs for Flexible Energy Storage Devices

In light of the rapid development of electronic technologies, portable electronic devices are promoted to evolve with fascinating flexibility, mi-niaturization and intellectualization. Flexible electronics with the features of bent, folded, twisted, stretched and coordinated deformations are now the booming fields of research. As a crucial component of flexible electronic devices, the design of reliable energy storage systems has become the key challenges towards the applications of flexible electronics. Traditional energy storage devices are rigid, which is easy to break under applied deformations. Accordingly, the separation of electrode materials and current collector seriously deteriorates the electrochemical perfor-mances and even causes a short circuit, resulting in safety issues. To this end, flexible energy storage devices, such as flexible Li-ion batteries, flexible Li-S batteries and flexible lithium metal batteries, have gained paramount interests in academia and industry. In recent years, great progress has been made in flexible energy storage devices based on intrinsic flexible materials assembly andrigid mate-rials flexible designs. Metal fibers (e.g., Al and Cu), polymer fibers (e.g., polypyrrole and polyaniline), and carbon-based materials (e.g., carbon nanofibers, carbon nanotubes and graphene) have so far been widely applied in flexible energy storage devices because of their intrinsic fle-xibility. While the other materials with the characteristics of brittleness, for example, lithium cobaltate and lithium titanate, can achieve a certain degree of flexibility after reasonable structural design. In addition, the practical application of flexible energy storage systems must meet the crite-rions in terms of high capacity, high efficiency, light weight, high safety and so on. This review dedicates to discuss the relationships between the microstructure of nanomaterials and the performance of devices. The preparation methods, mechanical properties and electrochemical performances of current flexible systems are briefly overviewed. Moreover, instructive perspectives are provided so that to enlighten more insightful contributions to flexible electronics. © 2020, Materials Review Magazine. All right reserved.