Functional Biopolymer Binders for High-Energy-Density and Ultrafast Cycling Lithium-Ion Batteries Operating at Extreme Temperatures (BLISET)

点击翻译按钮获取中文摘要

Lithium-ion (Li-ion) batteries were first commercialized in 1991 and were an immediate success. Almost thirty years later, that success has not faded and the demand for rechargeable batteries with high-energy-density and long cycle life has only increased. In addition to high-energy-density and long cycle life, safety, sustainability, cost-efficiency, high rate capability and wide temperature range operation are also required. The urge is strong and global. Batteries are expected to deliver great performance worldwide no matter if they are used in summery Brazil or wintry Siberia.In order to attain such goals, previous approaches included the optimization of the active material. However, that path is reaching its limit and, thus, attention has been turned to other components of batteries. One of the key component of batteries is the binder, which is responsible for homogenously dispersing and connecting the particles (active material and conductive carbon) that compose electrodes, to ensure a strong and long-lasting adhesion to the current collector, and to contribute to a faster diffusion of lithium ions. In this project, the aim is to develop a more environmentally friendly electrode manufacturing process, improve the rate capability and extend the operating temperature range of Li-ion batteries by improving the binder’s mechanical, thermal and conductive properties. To reach these goals a new type of binder based on biopolymers will be investigated. Besides the biopolymer, this new binder, a gel binder, also comprises an ionic liquid and a lithium salt. The combination of these three components leads to an improvement of the ionic conductivity, mechanical integrity and thermal stability and helps to create a conductive network. Thus, the active materials are fully utilized as a result of fast charge transfer kinetics and shorter lithium ion diffusion paths.Overall, Li-ion batteries with high-energy-density, long cycle life (2000-3000 cycles) and very high rate-capability (at least up to 10C for 1000 cycles, corresponding to a full battery charge in 6 minutes) in a wide range of temperatures (between -30 and 60 ºC) are intended. The optimization of the binder composition and the use of well-known active materials will grant this objective. The structural, morphological, mechanical and thermal properties of the samples prepared throughout this project will be evaluated by means of Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), tensile testing, electrolyte uptake measurements and thermogravimetric analysis (TGA), while the electrochemical characterization will be carried out through in situ spectroelectrochemistry, galvanostatic cycling (GCPL), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry not only at room temperature (25 ºC), but also at very low (-30 ºC) and high temperatures (60 ºC).