【作者】 田野；

【导师】 郑利强；

【作者基本信息】 山东大学 ， 材料与化工（专业学位）， 2024， 硕士

【摘要】 随着全球对碳排放的限制以及传统化石燃料的日渐枯竭,有必要开发更加高效且环保的能源转换和存储技术,因此各类电池技术应运而生。随着社会对高能量密度及高功率密度等储能设备需求的增加,人们也不断在探索提高电池产品功率和能量密度的途径。在传统的电解质中,阴阳离子均可以在其中自由移动,属于双离子导体。以锂离子电池为例,在充电过程中,锂离子向负极运动并与电子相结合,而对应的锂盐阴离子则向正极移动。而传统液体电解质中,由于锂离子复杂且庞大的溶剂化壳层,使得锂离子的迁移速率通常要小于阴离子,因此随着充电过程的进行,会出现严重的浓差极化现象,大量阴离子会在正极处富集,而负极处的阴离子会逐渐耗尽,从而形成空间电荷层,导致浓度梯度的积聚。这种浓度梯度限制了电池的充电或放电速率,产生浓度过电位,从而限制了电池的工作电压,并降低了电极的可使用厚度以及诱发枝晶生长等负面问题。降低浓差极化效应的解决方案之一就是尽可能的提高金属阳离子的迁移率,同时将阴离子的迁移率保持在最低水平,于是人们提出了近单离子传导的概念。提高电解质的金属离子迁移数是提高电池能量密度和充电速率重要方法,对设计出可支持高倍率充放电的电池具有重要意义。本文从设计可支持快速充电电池用电解质出发,设计近单离子传导电解质出发,对两亲性分子进行设计并调控其自组装行为来构筑近单离子传导电解质,进而优化电解质的倍率性能,并借助两性离子的特殊性质,对近单离子导体的性能进行调控。本论文由四部分组成:第一章:从应用目的出发,介绍了实现近单离子传导的意义以及构筑近单离子导体的方法;系统介绍了液晶的基本概念、液晶在离子传输方面的特性以及液晶电解质在电化学储能方面的应用;综述了两性离子的特点以及电化学应用;最后引出本论文的立题思想,研究内容和意义。第二章:设计了一种具有三氟甲基磺酰亚胺头基和疏水尾链的两亲性阴离子的锂盐,并通过阴离子的自组装行为限制阴离子的自由移动,构筑了近单离子传导液晶电解质与胶束电解质,其中液晶电解质的锂离子迁移数高达0.91,相比于传统的双离子传输电解质,使用近单离子传导电解质的锂离子电池具有更好的倍率性能与更高的容量保持率(200次循环后容量保持率73.1%)。为新型近单离子传导电解质的设计与开发提供了新的思路。第三章:通过可聚合锌盐与不同种类的两性盐设计和制备了不同的近单离子传导水凝胶电解质,相比较纯可聚合锌盐形成的水凝胶电解质,两性盐的引入降低了水凝胶中自由水的活性,降低了电池循环过程中的副反应。测试结果表明,基于开发的聚阴离子-两性盐水凝胶电解质的电池实现了超稳定(稳定运行时间超过2500小时)和高度可逆(平均库伦效率高达99.56%)的锌沉积/剥离,并在全电池测试中有效的减缓了水系锌离子电池的容量衰减速度,在水系锌离子电池中表现出强大的应用潜力。第四章:对本文的工作内容和结论进行了概括,总结了本文中工作的创新点与不足,并对基于液晶、凝胶构筑的近单离子传导电解质的更进一步的研究发展进行了展望。更多还原

【Abstract】 With the global constraints on carbon emissions and the gradual depletion of traditional fossil fuels,there is a need to develop more efficient and environmentally friendly energy conversion and storage technologies,leading to the emergence of various battery technologies.As the demand for energy storage devices with high energy density and high power density increases in society,people are constantly exploring ways to improve the power and energy density of battery products.In traditional electrolytes,both positive and negative ions can move freely,constituting a dual-ion conductor.Taking lithium-ion batteries as an example,during the charging process,lithium ions move towards the negative electrode and combine with electrons,while the corresponding lithium salt anions move towards the positive electrode.However,in traditional liquid electrolytes,due to the complex and bulky solvation shells of lithium ions,the migration rate of lithium ions is usually slower than that of anions.Consequently,as the charging process progresses,serious concentration polarization occurs,with a large number of anions accumulating at the positive electrode and gradually depleting at the negative electrode,forming a space charge layer and leading to the accumulation of concentration gradients.This concentration gradient limits the charging or discharging rate of the battery,causing concentration overpotential,thereby limiting the working voltage of the battery,reducing the usable thickness of the electrode,and inducing negative issues such as dendrite growth.One solution to reduce concentration polarization is to maximize the migration rate of metal cations in the electrolyte while keeping the migration rate of anions at the lowest level,thus the concept of nearly single-ion conduction is proposed.Improving the migration number of metal ions in the electrolyte is an important method to increase the energy density and charging rate of batteries,which is of great significance for designing batteries that can support high-rate charge and discharge.This paper starts from the design of nearly single-ion conducting electrolytes,designing and regulating the self-assembly behavior of amphiphilic molecules to construct nearly singleion conducting electrolytes,thereby optimizing the rate performance of electrolytes.Furthermore,it utilizes the special properties of amphoteric ions to regulate the performance of nearly single-ion conductors.This paper consists of four parts:Chapter one:Starting from the application perspective,this chapter introduces the significance of achieving nearly single-ion conduction and methods for constructing nearly single-ion conductors.It systematically introduces the basic concept of liquid crystals,the characteristics of liquid crystals in ion transport,and the application of liquid crystal electrolytes in electrochemical energy storage.It reviews the characteristics of amphiphilic ions and their electrochemical applications.Finally,it introduces the thesis idea,research content,and significance of this paper.Chapter two:A design is proposed for an amphiphilic anion lithium salt with a trifluoromethyl sulfonyl imide head group and hydrophobic tail chain.Through the selfassembly behavior of the anions,the free movement of anions is restricted,thus constructing nearly single-ion conducting liquid crystal electrolytes and micelle electrolytes.Among these,the lithium ion migration number of the liquid crystal electrolyte reaches up to 0.91.Compared to traditional dual-ion transporting electrolytes,lithium-ion batteries using nearly single-ion conducting electrolytes exhibit better rate performance and higher capacity retention.This chapter provides new insights for the design and development of novel nearly single-ion conducting electrolytes.Chapter three:Different nearly single-ion conducting hydrogel electrolytes are designed and prepared by incorporating polymerizable zinc salts with various types of amphiphilic salts.Compared to hydrogel electrolytes formed solely by polymerizable zinc salts,the introduction of amphiphilic salts reduces the activity of free water in the hydrogel,thereby mitigating side reactions during battery cycling.Test results demonstrate that batteries based on the developed poly-anion/amphiphilic salt hydrogel electrolytes achieve ultra-stability(operating stability exceeding 2500 hours)and high reversibility(average coulombic efficiency up to 99.56%)for zinc deposition/stripping.These batteries effectively mitigate the capacity decay rate in aqueous zinc-ion batteries during full-cell testing,showcasing strong potential applications in aqueous zinc-ion batteries.Chapter four:This chapter provides a summary of the work and conclusions of this paper,outlining the innovations and limitations of the work conducted herein.It also offers prospects for further research and development based on liquid crystal and hydrogel-based nearly singleion conducting electrolytes.更多还原