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。需要能量存储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为3.8GW，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网格规模应用的决定性指标。当在每个循环中完全充电/放电时，锂离子电池单元通常将仅持续300-500个循环，这需要显著改进以降低每个循环的存储成本。** 与电极退化和电池故障相关的持续挑战之一是由离子嵌入引起的应力，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发展起来，并提供了宝贵的见解的影响，应力积累和释放（例如，应力引起的结构变化）。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差距。最近，我们开发了一种原位解决方案，使用微悬臂梁传感器定量测量电极上的局部应力，该传感器对应力变化具有极高的灵敏度。基于新开发的应力测量解决方案和我们的经验，在原位显微镜，我们建议调查的局部应力演化的薄膜电极与设计的纳米结构和解释的应力演化的背景下的动态变化的电极的杨氏模量，体积和化学成分。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沿着变化。** 拟议的研究将为持久电极设计中的两个关键问题提供答案：最佳充电/放电条件是什么，以及最有效的纳米工程方法是什么？这些答案将有助于降低每个周期的储能成本，并加快加拿大可再生能源的部署。该计划涵盖了基础科学应用研究的设计和集成系统的开发。作为该项目的一部分，我们希望在新领域培养一名研究生和两到三名本科生，涉及材料科学，电化学，纳米工程，纳米力学和储能。两名博士后研究员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.**