Resolving the Localized Stress Evolution: Toward Long-lasting Rechargeable Batteries

风能和太阳能是加拿大增长最快的电力来源。风能和太阳能最大的问题是它们是间歇性的。需要一种储能解决方案来缓冲电力波动。可充电电池被认为是在不久的将来最有前途和实用的解决方案。到2017年，全球并网电池储能市场规模为3.8 GW，预计到2022年将达到23.4GW。在加拿大，到2018年，可充电电池（50兆瓦）将占电网总储能容量的81%。每周期的存储成本是电网规模应用的决定性指标。在每次循环完全充电/放电时，锂离子电池通常只能持续300-500次循环，为了降低每次循环的存储成本，这需要显著改进。******与电极退化和电池失效相关的持续挑战之一是离子插入引起的应力，伴随着电极材料的大体积波动。许多原位显微镜和光谱技术已经被开发出来，并为应力积累和释放的影响（例如应力引起的结构变化）提供了有价值的见解。然而，局部应力的强度仍然知之甚少，这是提高可充电电池循环寿命的知识空白。最近，我们开发了一种原位解决方案，用于定量测量电极上的局部应力，使用微悬臂传感器，对应力变化具有极高灵敏度的独立式梁。基于新开发的应力测量溶液和原位显微镜的经验，我们提出研究设计纳米结构薄膜电极的局部应力演化，并在电极的杨氏模量、体积和化学成分的动态变化背景下解释应力演化。利用原位透射电子显微镜（TEM）和原位原子力显微镜（AFM）等多种原位技术监测材料的物理和化学性质随应力的变化。******提出的研究将为长期电极设计中的两个关键问题提供答案：最佳充放电条件是什么，以及什么是最有效的纳米工程方法来最小化应力产生？这些答案将有助于降低每个周期的能源储存成本，并加速加拿大可再生能源的部署。该课程涵盖了基础科学到集成系统设计和开发的应用研究。作为该项目的一部分，我们希望在材料科学、电化学、纳米工程、纳米力学和能源存储等新领域培养一名研究生和两到三名本科生。两名博士后也将通过该项目获得宝贵的研究经验

Wind and solar energy are the fastest growing sources of electricity in Canada. The biggest concern with wind and solar energy is that they're intermittent. An energy storage solution is required to buffer the electricity fluctuation. Rechargeable batteries are considered as the most promising and practical solution in near future. The global grid-connected battery energy storage market is 3.8 GW by 2017, which is expected to reach 23.4GW by 2022. In Canada, rechargeable batteries (50 MW) take 81% of the total grid energy storage capacity by 2018. The storage cost per cycle is a determinant index for grid-scale applications. When fully charged/discharged in each cycle, lithium-ion battery cells will typically last only 300-500 cycles, which needs to be remarkably improved in order to reduce the storage cost per cycle. ******One of the persistent challenges associated with electrode degradation and battery failure is the stress induced by ion intercalation, companied by large volume fluctuation of electrode materials. Many in situ microscopy and spectrometry technologies have been developed and provided valuable insights into the impacts of the stress buildup and release (e.g. the stress-induced structures changes). However, the strength of the localized stress remains poorly understood, which is a knowledge gap in improving the cycle life of rechargeable batteries. Recently we developed an in situ solution to quantitively measure the localized stress on electrodes using microcantilever sensors, free-standing beams with extremely high sensitivity to stress variations. Based on the newly developed stress measurement solution and our experience with in situ microscopes, we propose to investigate the localized stress evolution in thin film electrodes with designed nanostructures and to interpret the stress evolution in the context of the dynamic changes of electrodes in Young's modulus, volume, and chemical composition. Multiple in situ technologies, such as in situ transmission electron microscopy (TEM) and in situ atomic force microscope (AFM), will be utilized to monitor the physical and chemical properties changes along with the stress. ******The proposed research will provide answers to two critical questions in long-lasting electrodes design: What is the optimal charge/discharge conditions, and what is the most efficient nano-engineering method to minimize the stress generation? These answers will help to reduce the energy storage cost per cycle and accelerate the deployment of renewable energy in Canada. This program covers basic science to applied research to the design and development of integrated systems. As part of the project, we would like to train a graduate student and two to three undergraduate students in the new area across materials science, electrochemistry, nano-engineering, nano-mechanics and energy storage. Two postdoctoral fellows will also gain valuable research experience through the project.**