Collaborative Research: Elucidation of the Grotthuss Topochemistry in Reticular Electrodes for Fast Proton Batteries

在这个由NSF材料研究部门的固态和材料化学计划支持的合作项目中，加州大学滨江分校和俄勒冈州州立大学的两个研究小组研究了氢离子在受限水网络中扩散速度的基本方面。当金属离子在水中移动时，它们会推动水分子通过。众所周知，氢离子以完全不同的方式迁移，而且迁移速度更快。研究人员详细研究了这个过程是如何工作的，以及是什么使它比金属离子的扩散快很多倍，例如是什么使它比电池中的锂离子快。有几个因素可以使非常快的氢离子电池具有数百万次充电和放电的潜力，因此提供了实现电化学能量存储圣杯的绝佳机会：同时实现电池的能量密度和电容器的功率和循环寿命。丰富的氢也使氢离子电池成为电网级蓄电池的一个有前途的候选者，这些蓄电池需要从风能和太阳能等间歇性电源提供连续可靠的电力供应。这些领域的知识和相关技术的进步有助于美国保持经济竞争力。此外，该项目还针对学生和广大公众制作教育视频，介绍储能概念及其在社会中的作用。在这两个机构中，研究生和本科生的培训将使他们具备进入能源技术领域的劳动力所需的技能，并开展额外的推广活动。技术概述现有的电池化学知识是建立在这样一种理解之上的：动力学是由工作离子的去溶剂化和车载扩散决定的。该合作项目的研究得到了NSF材料研究部固态和材料化学项目的支持，探索了电池化学的新范式，通过使用质子作为含水电解质的工作离子，电荷传导不依赖于离子通过主电极的长距离物理迁移，通过质子沿着电极中的结晶水网络位移的Grotthuss机制，电荷的范围移动。通过Grotthuss机制的质子运输涉及水的键合拓扑结构中的准粒子缺陷的运动。它从根本上不同于金属阳离子的车辆运输，可以产生超快的插入动力学和提供在超低温下提供高功率的电池的能力。该项目的重点是特恩布尔蓝及其类似化合物家族的质子传输和存储机制。这些系统有一个开放和缺陷的晶体结构，拥有一个内部的结晶水网络。结晶水网络提供了Grotthuss扩散的途径，使质子传输和储存的动力学非常快，即使在远低于水的冻结温度的温度下。该项目测试了中心假设，即质子在该系统中的传输性能取决于周围宿主框架对结晶水的氢键网络施加的拓扑结构。为了验证这一点，研究人员A。确定普鲁士蓝类似物中水网络的拓扑特征，从原子到介观尺度，以及它们在Grotthuss拓扑化学中所起的作用; B.阐明在所有电荷状态下普鲁士蓝类似物内的水网络中质子插入、储存和运输的机制;以及c.该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical Summary With this collaborative project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, two research groups at the University of California Riverside and Oregon State University investigate fundamental aspects of how fast diffusion of hydrogen ions occurs in confined networks of water. When metal ions move though water, they push past the water molecules as they go. It is already known that hydrogen ions migrate in a completely different manner and faster. The researchers study in detail how this process works and what makes it many times faster than the diffusion of metal ions, for example what makes it faster than that of lithium ions in batteries. Several factors can enable very fast, hydrogen-ion batteries that have the potential to be charged and discharged for millions of cycles, and so present a remarkable opportunity to realize the Holy Grail of electrochemical energy storage: to achieve simultaneously the energy densities of batteries and the power and cycle life of capacitors. The abundance of hydrogen also makes hydrogen-ion batteries a promising candidate for the grid-level storage batteries that are needed to provide a continuous and dependable electricity supply from intermittent power sources such as wind and solar energy. Advancing knowledge and the associated technology in these areas aids the United States to remain economically competitive. Additionally, the project produces educational videos targeted to students and the broader public that present concepts in energy storage and its role in society. Training of graduate and undergraduate students with the skills needed to enter the workforce in the energy technology sector and additional outreach activities take place at both institutions.Technical Summary The existing knowledge of battery chemistry is built upon the understanding that the kinetics are dictated by desolvation and vehicular diffusion of the working ion. The research in this collaborative project, which is supported by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, explores a new paradigm of battery chemistry where by using protons as the working ions with an aqueous electrolyte, charge conduction does not rely on the long-range physical migration of ions through the host electrode but instead obtains long-range movement of charge via the Grotthuss mechanism of proton displacement along the crystal water network in an electrode. Transport of protons via the Grotthuss mechanism involves the movement of a quasiparticle defect in the bonding topology of water. It is fundamentally different from the vehicular transport of metal cations and could give rise to ultra-fast insertion kinetics and the ability to provide batteries that deliver high power at ultra-low temperatures. The project focuses on mechanisms of proton transport and storage in Turnbull blue and its family of analog compounds. These systems have an open and defected crystal structure that hosts an internal network of crystal water. The crystal water network provides pathways for Grotthuss diffusion, making the kinetics of proton transport and storage exceedingly fast, even at temperatures well below the freezing temperature of water. This project tests the central hypothesis that the transport performance of protons in this system depends on the topology imposed on the H-bonding network of crystal water by the surrounding host framework. To test this, the researchers a. determine the topological characteristics of the water network in Prussian blue analogs, from the atomic to the mesoscopic scale, and the role they play in Grotthuss topochemistry; b. elucidate the mechanisms of proton insertion, storage, and transport in the water network within Prussian blue analogs at all states of charge; and c. formulate testable design principles that can guide the development of new reticular materials for proton transport and storage.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.