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

锂离子（Li-ion）电池于1991年首次商业化，并立即取得了成功。近30年后，这一成功并未消退，对高能量密度和长循环寿命的可充电电池的需求只会增加。除了高能量密度和长循环寿命外，还需要安全性、可持续性、成本效益、高速率能力和宽温度范围的操作。这种冲动是强烈而全球性的。无论是在夏季的巴西还是冬季的西伯利亚，电池都有望在全球范围内提供出色的性能。为了达到这样的目标，以前的方法包括对活性物质的优化。然而，这条道路已经达到了极限，因此，人们的注意力已经转向电池的其他组件。粘合剂是电池的关键部件之一，它负责均匀地分散和连接构成电极的颗粒（活性材料和导电碳），以确保与电流收集器的牢固和持久的粘附，并有助于锂离子的更快扩散。在这个项目中，目的是开发一种更环保的电极制造工艺，提高倍率能力，并通过改善粘合剂的机械、热学和导电性能来扩展锂离子电池的工作温度范围。为了达到这些目标，将研究一种基于生物聚合物的新型粘结剂。除了生物聚合物外，这种新的粘合剂，凝胶粘合剂，还包括离子液体和锂盐。这三种成分的结合可以改善离子电导率、机械完整性和热稳定性，并有助于形成导电网络。因此，由于快速电荷转移动力学和较短的锂离子扩散路径，活性材料被充分利用。总体而言，锂离子电池具有高能量密度，长循环寿命（2000-3000次循环）和非常高的倍率能力（1000次循环至少高达10C，相当于在6分钟内充满电池），适用于宽温度范围（-30至60ºC）。粘合剂组成的优化和已知活性材料的使用将实现这一目标。通过傅里叶变换红外光谱（FTIR）、x射线衍射（XRD）、扫描电镜（SEM）、x射线光电子能谱（XPS）、拉伸测试、电解质摄取测量和热重分析（TGA）对整个项目制备的样品的结构、形态、力学和热性能进行评估，而电化学表征将通过原位光谱电化学进行。恒流循环（GCPL）、电化学阻抗谱（EIS）和循环伏安法不仅适用于室温（25℃），而且适用于极低温度（-30℃）和高温（60℃）。

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).