数位青年学者今日欢聚，聚焦电池未来！

报告人简介及报告摘要

实现“碳达峰、碳中和”目标，研发储能技术必不可少。超级电容器作为一种相对电池充放电更快、循环寿命更长而能量密度较低的电能储存装置，在储能技术领域中正受到越来越多的关注。离子液体因具有工作电压高、工作温度宽、热稳定性好、挥发性极低等优点，已成为一种新型电解液，用于高能量密度超级电容器的研发。深入揭示超级电容器储能过程中电极-离子液体储能界面的微观结构及其动态形成过程，有助于认知其储能机理，以研发出高性能储能器件。近些年来，我们利用分子模拟方法，采用具有不同拓扑结构与表面特征的电极和具有不同分子构型与物化性质的离子液体电解液，研究了超级电容器中的微纳尺度界面与输运现象，分析了储能界面结构及其动态形成过程，并结合实验测量，探索了储能界面的微观结构和离子输运与电容特性之间的内在关联机制，为新型超级电容器的研发提供了新思路、新方案。

超级电容器因具有较高的功率密度、较宽的工作温度范围以及优异的长循环性能等突出特征在众多领域发挥着传统电容器和电池不可替代的作用。优化高安全性和环境友好的水系超级电容器体系，打破水分子固有的热力学特性限制，提升其能量密度一直是国内外备受关注的一个学科前沿和富有挑战性的热点课题之一。本报告系统分析了水系超级电容器的研究现状，优化了水系超级电容器体系的关键组成，包括碳和水滑石及其派生的电极材料、集流体和超越高盐/粘度“water-in salt”（WIS）的新型低盐/粘度高压水系电解液等。最终，实现了水系超级电容器存储电荷的能力，输出电压窗口和能量密度的有效提升，为高电压、高能量和高倍率水系超级电容器的发展提供可资借鉴新思路和技术支持。

超级电容器具有功率密度高、充电时间短、使用寿命长等优点；在启动电源、工业节能、航空航天等诸多领域具有重要应用前景。但是其能量密度密度仅为5-10 Wh/kg，制约了超级电容器的广泛使用。本报告将结合课题组的最新研究进展，深入探讨超级电容器关键材料的研制和器件制备，主要包括：1）电极材料设计与制备; 包括石墨烯基多级次电极材料、氮掺杂电极材料；2）高比能器件的开发。通过对器件结构的调控和大容量器件技术的创新，开发具有优良电化学性能的高能量密度混合型电容器。

发展大规模储能的二次电池不仅需要具有适宜的电化学性能，更需考虑资源成本和环境效益等应用要求。而锂离子电池用于大规模储能可能受到锂资源的制约，因此，从资源与环境方面考虑，具有与锂离子电池相似电化学性能的钠离子电池体系作为储能电池更具应用优势。然而，从目前的技术现状来看，几类不同的嵌钠正负极材料虽显现出可观的容量与较好的循环性，但能量密度与功率密度尚待提高。过渡金属氧化物、氰基正极材料和磷酸盐体系，以及硬碳负极材料最有希望用于实用化钠离子电池体系，但这类材料的初始充放电效率和循环稳定性仍有待改善。本报告简要分析嵌钠正负极材料的一些问题，讨论适合嵌钠反应的一些思路，并结合本课题组的研究工作讨论钠离子电池正极材料及硬碳负极材料的应用可行性。

向下滑动查看所有内容

高比能(能量密度)蓄电池是新能源汽车、分布式储能等国家战略新兴产业的“心脏”，而高安全性则是任何电池体系实际应用的先决条件。近年来，备受青睐的高比能有机系锂离子电池(LIBs)所带来的安全隐患日益突显。例如，采用LIBs的手机、电动车、储能电站等频发自燃、自爆事故，这些已危及人们的生命财产和人身安全。相比之下，水性电池（ABs）具有天然的高安全性、低成本、快充特性及制造工艺简易等优势，是下一代安全电源及大规模储能器件的重要候选。但是，相比于已广泛应用的有机锂离子电池，当前商用水系电池面临的最大挑战是比能低。要想提升水系电池的能量密度，一是提升电极的比容量，二是拓宽电化学窗口。跳出现有电极体系及方案，该报告将系统介绍其团队通过构建新型高容量/高电压反应电对、电解液溶剂化结构调控、稳定水-金属界面等水系电化学策略，最终为高比能水系电池设计提供系统的器件化解决方案。

The energy crisis and greenhouse effect have aroused enormous research effort for developing effective electrochemical energy storage systems (EESs). Metallic Li/Zn is widely considered as the ultimate anode for the next-generation high-energy-density rechargeable batteries owing to its extremely high theoretical specific capacity and the low reduction potential. Despite these obvious superiorities, the practical application of the Li/Zn metal anode still faces great challenges associated with the repeated plating/stripping cycles. Particularly, inhomogeneous deposition leads to the formation and growth of dendrites, which could puncture the separator and cause internal short circuit. Among the available strategies, utilization of 3D porous/hollow carbonaceous scaffolds as both the Li/Zn host and current collector has been considered as an attractive strategy for dendrite-free Li/Zn metal batteries. Fabricating hollow nanostructures with high complexity by manipulating their geometric morphology, chemical composition, building block, and interior architecture has shown huge impact on the development of 3D porous/hollow hosts for Li/Zn metal batteries. This report summarizes our recent progress towards complex hollow nanostructure design as functional host for Li/Zn metal anode and take a prospect for its research future.

The rapid growth in battery demand, combined with resource issues and supply risks, raises questions about whether alternative battery technologies are needed that complement or partly replace lithium-ion and lead-acid batteries. A range of alternatives such as high temperature batteries or redox-flow systems are already available, with Na-ion batteries (SIBs or NIBs) being the latest contender.[1],[2]

The main goal for SIBs is to develop batteries based on abundant, non-critical elements that reach, at the same time, similar energy densities compared to Li-ion batteries (LIBs). SIBs have the potential to be more cost effective than LIBs while reaching similar cycle life. As a major advantage compared to other alternative cell chemistries, SIBs can be produced on the same manufacturing lines like LIBs therefore taking advantage of existing manufacturing technology. Recent announcements by Chinese cell and car manufacturers are further raising the interest in this technology. In fact, the first Na-ion Gigafactory has opened in November 2022 in China and Chinese OEMs announced to implement SIBs in electric vehicles. This clearly shows that the technology is now reaching commercialization.

On the other hand, there are needs for further improvements in electrode materials and electrolytes to further develop the technology. This talk gives an overview on Na-ion batteries and recent developments. The state-of-the art will be summarized followed by a discussion on what materials can be used (and not used) compared to Li-ion batteries. Specific examples include how nanoscale chemical strategies can be used to tune the properties of layered oxides as cathode materials for SIBs[3], and how the intercalation of solvated ions enables a new “electrode chemistry”.[4],[5] The talk will also include an example of how X-ray tomography can be used to study morphological changes and particle displacement during battery charging/discharging.[6]

[1] Sodium-ion batteries: Materials, Characterization and Technology ISBN: 978-3-527-34709-4, Wiley Dec 2022, Titirici/Adelhelm/Hu (Editors)

[2] P. Nayak et al. Angew. Chemie. Int. Ed., 2018, DOI: 10.1002/anie.201703772

[3] L. Yang et al. Adv. Functional Materials, 2021, DOI: 10.1002/adfm.202102939

[4] G. Ferrero et al. Adv. Energy Materials, 2022, DOI: 10.1002/aenm.202202377

[5] G. Avall et al. Adv. Energy Materials, 2023, DOI: 10.1002/aenm.202301944

[6] Z. Zhang et al. Adv. Energy Materials, 2023, DOI: 10.1002/aenm.202203143

为了实现更高的电池容量和更大的能量密度，对于一些新型电池体系的研究迫在眉睫。锂氧电池因其理论能量密度可以达到锂离子电池的10倍左右而成为研究的热点，但是目前能存在诸多问题亟待解决。目前锂氧电池的相关研究集中于正极，关于锂负极的研究是许多电池体系的共性问题，可以互相借鉴。关于正极的研究聚焦在两个方面，更高效的正极催化剂和更少的副反应。在放电过程中，正极侧会发生氧气还原为过氧化锂（Li2O2）的反应，而充电过程中放电产物过氧化锂被分解为氧气，但是该反应的过电位很大，亟需高效催化剂改善充放电过电位。同时，由于催化反应机理并不明晰，为催化剂的设计带来很大的挑战。另一方面，为了提升锂氧电池的循环性能，需要尽可能减少充放电过程中的副反应，推迟电极表面的钝化。本报告将从这两方面出发，介绍锂氧电池正极反应中的主要挑战与机遇，展望锂氧电未来的可能发展方向。