论文总字数：22984字

摘 要

传统的商用锂离子电池一般采用有机液体电解质隔膜，极易产生一系列安全问题。而且隔膜材料还难以降解，会对环境造成不可逆的伤害。因此，研究安全环保的聚合物电解质显得尤为重要。但是固态电解质存在导电率较低的问题，所以综合了液态和固态电解质优点的凝胶电解质脱颖而出，其中纤维素基凝胶电解质不仅解决了锂电池的漏液问题，有效提高了锂离子电池的安全性能，而且纤维素作为环境友好型材料，不会对环境造成污染。

然而，但随着人类对能源存储技术的要求越来越高，锂离子电池已经不再有所突破，人们又将目光转向了锂金属材料，无锂正极与Li/C负极组合在电池水平上可能提供较高的的能量密度，由于负极已经是含锂材料，正极可以不用含有锂。解决了含锂正极成本较高的问题，考虑到无锂正极具有成本低、无污染、工艺简单、耐水性和高能量密度等诸多优点，它在锂电池中的应用可能取得良好成果。

本实验研究了以下内容：羟乙基纤维素凝胶电解质的制备和构建锂金属电池

一、羟乙基纤维素凝胶电解质的制备

采用冻干法制备羟乙基纤维素膜（HEC），并对所制得的羟乙基纤维素膜（HEC）进行基础的性能表征。纤维素膜吸收电解液制成纤维素凝胶电解质，该电解质在室温下的离子导电率0.62 mS cm^-1,离子迁移0.33，与商用隔膜Celgard2400相比较好。由此可见，该种羟乙基纤维素凝胶电解质在保持电池的性能上降低成本并且对环境无害。

二、构建锂金属电池

MnO₂材料被广泛应用于电池中，储量丰富，价格低廉，对环境友好，具有良好的电化学性能。但本身的导电率不高在实际应用中比容量较低。实验中将MnO₂、乙炔黑和PVDF按照一定比例混合制成极片。由制备成的羟乙基纤维素凝胶电解质和MnO₂极片构建锂金属电池并测试其性能，结果表明，在电流为100 mA时，其质量比容量达到70 mAh/g。该电池具有良好的循环稳定性且展示出优异的倍率性能。

关键词：锂金属电池 纤维素膜 纤维素凝胶聚合物电解质 无锂正极

Construction and Performance Study of Lithium Solid State Battery Based on Lithium-free Cathode Material and Cellulose-based Gel Electrolyte

Abstract

Traditional commercial lithium-ion batteries commonly used organic liquid electrolyte membrane, easy to produce a series of safety problems.And the diaphragm material is difficult to degrade, can cause irreversible damage to the environment.Therefore, it is very important to study the safety and environmental protection polymer electrolyte. However, the solid electrolyte has low conductivity. Therefore, the gel electrolyte which combines the advantages of liquid and solid electrolytes talent shows itself. Cellulose based gel electrolyte not only solves the leakage problem of lithium batteries, but also improves the safety performance of lithium ion batteries. Moreover, cellulose as an environment-friendly material will not pollute the environment.

However, the most advanced lithium-ion battery still can not meet the increasing demand of high energy density, so the lithium metal battery re-enter the vision of scientists. Free lithium anode with Li/C composite at the battery level may provide a higher energy density, As the negative electrode is already lithium containing material, the positive electrode can not contain lithium. Considering the potential advantages of lithium-free anode: low cost, environment-friendly, easy to synthesize, insensitive to water and high energy density, it is more competitive than lithium-containing anode.

The following contents were studied: preparation of hydroxyethyl cellulose gel electrolyte and construction of lithium metal battery.

Preparation of hydroxyethyl cellulose gel electrolyte:

Hydroxyethyl cellulose (HEC) membrane was prepared by freeze-drying method, and its basic physical and chemical properties were characterized. The cellulose membrane absorbs the electrolyte to form cellulose gel electrolyte. The ionic conductivity of the electrolyte is 0.62 mS cm^-1 at room temperature, and the ion migration is 0.33, which is better than that of the commercial membrane Celgard2400. It can be seen that the hydroxyethyl cellulose gel electrolyte reduces the cost of maintaining the performance of the battery and is harmless to the environment.

Building lithium metal battery:

MnO₂ materials for lithium metal batteries are widely used in batteries, which are abundant in reserves, cheap in price, environmentally friendly and have good electrochemical performance. But its conductivity is not high, and its specific capacity is low in practical application. In the experiment, with the MnO₂, acetylene black and PVDF according to certain proportion to make plate. The lithium gold II battery was prepared by the preparation of hydroxyethyl cellulose gel electrolyte and MnO₂ polar plate, and its performance was tested. The results showed that when the current was 100mA, the specific mass of lithium gold was 70mAh g^-1. The battery has good cycle stability and excellent rate performance.

Key words: lithium metal battery;cellulose membrane;cellulose gel polymer electrolyte;lithium free cathode

目录

摘要 I

Abstract II

第一章 绪论 1

1.1引言 1

1.2 锂电池简介 3

1.2.1锂电池发展概况 3

1.2.2 锂金属电池工作原理 4

1.2.3 锂金属电池正极材料 4

1.2.4 锂金属电池负极材料 4

1.2.5 锂电池电解质 4

1.3 聚合物电解质简介 5

1.3.1 聚合物电解质发展概况 5

1.3.2 聚合物电解质分类 5

1.4 本论文的研究目的和主要内容 7

1.4.1 研究目的 7

1.4.2 研究内容 7

第二章 实验材料与研究方法 8

2.1 实验试剂 8

2.2 实验仪器 8

2.3 材料物理性能表征 9

2.3.1 形貌表征 9

2.3.2 吸液率与孔隙率表征 10

2.3.3 力学性能表征 10

2.4电化学性能测试 10

2.4.1离子电导率测试 10

2.4.2 线性扫描伏安测试 10

2.4.3 锂离子迁移数测试 11

2.4.4 循环伏安测试 11

2.4.5 恒流充放电测试 11

第三章 羟乙基纤维素基凝胶聚合物电解质 12

3.1引言 12

3.2 羟乙基纤维素基凝胶聚合物的制备 12

3.3 羟乙基纤维素基凝胶聚合物电解质的物理性质 14

3.3.1 表面微观形貌 14

3.3.2吸液率和孔隙率 14

3.3.3力学性能 15

3.4 羟乙基纤维素基凝胶聚合物电解质的电化学性质 16

3.4.1 离子电导率 16

3.4.2 电化学窗口 16

3.4.3 循环伏安曲线 17

3.4.4 锂离子迁移数 18

3.4.5 循环性能和倍率性能 19

3.5 本章小结 20

第四章 结论与展望 21

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