Composite Silicon Anodes for Energy Storage, Sensing, and Actuation in Multifunctional Lithium Ion Devices

本项目探索复合硅阳极用于多功能锂离子（Li-ion）基器件的潜力。锂离子电池广泛用于高功率和能量密度的应用，如电动汽车、手机、笔记本电脑和无人机。硅阳极有望实现更高的电化学能量密度，但由于硅在完全锂化时所经历的高体积膨胀，使其使用变得复杂。此外，硅阳极锂离子电池的开路电压对机械应力高度敏感。该项目将利用这些效应来创造新的多功能结构，能够集成能量存储、机械驱动、惯性、振动和化学传感。这种新型设备的基本性能和权衡将通过建模、设计优化和实验测试来表征。项目成果将对各种技术产生广泛影响，包括医疗微型机器人、可穿戴电子设备和电动汽车。由研究生和本科生组成的多元化研究团队将共同完成基础研究任务，并在转化工程研讨会上学习将基础研究转化为商业产品和系统的关键技能。本项目通过理论、实验和设备设计研究，寻求对锂化硅复合材料结构耦合电化学和力学动力学的基本理解。将结合电化学和力学的基本方程来预测这些活性结构所提供的位移和力。控制偏微分方程将通过可支持的工程假设，线性化和模型降阶来简化，以产生数字上有效的模型，提供对潜在物理和化学的深刻理解。这些模型将依次用于设计复合阳极的化学、形态和中尺度结构，包括硅、粘合剂和导电添加剂，以探索电动力和机械动力之间的帕累托边界。这是第一次，与硅复合材料锂化相关的大体积变化将被利用来创建在充电和放电时以所需方式移动的驱动结构。此外，larch<s:1> -卡恩电位将首次被用于制造能够自我感知其压力状态的电池。从新颖的第一性原理模型和概念介结构开始，完整的控制方程将被简化，以有效和准确地预测基于施加负载和电流输入的输出电压。化学成分、形态和结构将会改变，以研究能量储存和对施加载荷的敏感性之间的权衡。新的驱动和自传感能量存储结构将与标准阴极和电解质配对，并对电气，机械和传感器性能进行测试。该项目的结果将封装在第一性原理模型中，该模型将通过电压、电流、位移和施加负载的测量进行实验验证。

This project explores the potential of composite silicon anodes for multifunctional lithium ion (Li-ion) based devices. Li-ion batteries are widely used for high power and energy density applications, such as electric vehicles, cell phones, laptop computers, and unmanned aerial vehicles. Silicon anodes promise even higher electrochemical energy densities, but their use is complicated by the high volumetric expansion that silicon undergoes when fully lithiated. Furthermore, open-circuit voltage in Li-ion cells with silicon anodes is highly sensitive to mechanical stress. This project will harness these effects to create novel multifunctional structures capable of integrated energy storage, mechanical actuation, and inertial, vibration, and chemical sensing. The fundamental capabilities and trade-offs of this new and novel class of devices will be characterized through modeling, design optimization, and experimental testing. Project outcomes will have broad impacts on a variety of technologies, including medical microrobots, wearable electronic devices, and electric vehicles. A diverse research team of graduate and undergraduate students will work together on fundamental research tasks, as well as in translational engineering workshops to learn skills crucial to converting fundamental research into commercial products and systems.This project seeks a fundamental understanding of the coupled electrochemical and mechanical dynamics of lithiated Si composite structures, through theoretical, experimental, and device design research. Fundamental equations of electrochemistry and mechanics will be combined to predict the displacement and force provided by these active structures. The governing partial differential equations will be simplified via supportable engineering assumptions, linearization, and model order reduction, to produce numerically efficient models providing an insightful understanding of the underlying physics and chemistry. These models will be used in turn to design the chemistry, morphology, and mesoscale structure of composite anodes, including the Si, binder, and conductive additives, to explore the Pareto frontier between electrical and mechanical power. For the first time, the large volume change associated with lithiation of Si composites will be harnessed to create actuated structures that move in a desired fashion when charged and discharged. Also for the first time, the Larché-Cahn potential will be used to make batteries that self-sense their stress state. Starting from novel, first principle models and a notional mesostructure, the full governing equations will be simplified to efficiently and accurately predict output voltage based on applied loads and electrical current input. Chemical composition, morphology, and structure will be varied to study the tradeoff between energy storage and sensitivity to applied loads. The new actuating and self-sensing energy storage structures will be paired with standard cathodes and electrolytes, and tested for electrical, mechanical, and sensor performance. The results of the project will be encapsulated in first-principles models, which will be experimentally validated against measurements of voltage, current, displacement, and applied load.