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论文中文题名:

 金属化合物用于锂硫电池正极及隔膜改性研究    

姓名:

 周犇    

学号:

 20211025012    

保密级别:

 公开    

论文语种:

 chi    

学科代码:

 0805    

学科名称:

 工学 - 材料科学与工程    

学生类型:

 硕士    

学位级别:

 工学硕士    

学位年度:

 2023    

培养单位:

 西安科技大学    

院系:

 材料科学与工程学院    

专业:

 材料科学与工程    

研究方向:

 新能源材料与器件    

第一导师姓名:

 卢海    

第一导师单位:

 西安科技大学    

论文提交日期:

 2023-06-20    

论文答辩日期:

 2023-06-04    

论文外文题名:

 Studies on cathode and separator modifications by metallic compounds for lithium-sulfur batteries    

论文中文关键词:

 锂硫电池 ; 正极 ; 隔膜 ; 改性 ; 金属化合物    

论文外文关键词:

 Li-S battery ; Cathode ; Separator ; Modified ; Metallic compounds    

论文中文摘要:

锂硫电池作为一种高能量密度储能装置在近几十年里受到广泛关注。然而,中间产物多硫化物引起的穿梭效应、反应动力学缓慢等问题导致电池循环寿命短、可逆容量低,严重制约了锂硫电池的实际化应用。为此,本文以解决多硫化物引起的上述问题为目的,将不同类型的金属化合物用于锂硫电池正极、隔膜改性,拟利用金属化合物物理、化学限域多硫化物并加快硫物种转化,整体提升锂硫电池电化学性能。本文主要研究内容及获得的结论如下:

(1)在碳布上原位生长镍原子掺杂硫化钼形成NMS@CC,作为锂硫电池的液态正极基体。合成的NMS@CC对多硫化物具有较强的吸附能力,制备的液态多硫化物正极0.2C初始放电比容量为1352.3 mAh/g,经充放电循环200圈后仍保持了930.1 mAh/g,当正极硫载量提升至4.3 mg/cm2时仍有良好的循环性能。

(2)通过水热法合成了具有钙钛矿结构的锰酸镧(LMO)材料,将其涂覆在PP隔膜表面构筑LMO@PP复合隔膜。该复合隔膜能够充分阻挡多硫化物并加快其可逆转化。在1C电流密度下,使用LMO@PP隔膜组装的锂硫电池初始放电比容量达到904.1 mAh/g,经500圈循环后可逆容量仍具有577.9 mAh/g,每圈循环的容量衰减率仅为0.072%。

(3)通过改良的水热法制备出纳米片状LMO材料,将其作为硫碳复合正极材料的添加剂。该LMO纳米片具有出色的吸附多硫化物的能力和对硫物种的催化作用。在1 C电流密度下,添加LMO制备的硫碳复合材料的初始放电比容量为795.9 mAh/g,经100圈循环后的容量保持率高,同时具有良好的倍率工作特性。

论文外文摘要:

Lithium sulfur batteries as a high energy density energy storage device has been widely concerned in recent decades. However, the shuttle effect caused by intermediate polysulfide, slow reaction kinetics and other problems lead to short cycle life and low reversible capacity of the battery, which seriously restricts the practical application of lithium sulfur batteries. Therefore, in order to solve the above problems caused by polysulfide, different types of metallic compounds are used to modify the cathode and separator of lithium sulfur batteries, and it is intended to use metallic compounds to physically and chemically limit polysulfide and accelerate the transformation of sulfur species, so as to improve the electrochemical performance of lithium sulfur batteries. The main research contents and conclusions of this paper are as follows:

Nickel atoms doped molybdenum sulfide were grown in situ on the carbon cloth to form NMS@CC, which was used as the liquid cathode substrate of lithium sulfur batteries. The synthesized NMS@CC has strong adsorbability to polysulfides. The prepared liquid polysulfide cathode has an initial specific discharge capacity of 1352.3 mAh/g at 0.2 C, which still maintains 930.1 mAh/g after 200 cycles, and still has good cycle performance when the sulfur loading is increased to 4.3 mg/cm2.

Lanthanum manganate (LMO) with perovskite structure was synthesized by hydrothermal method and coated on the surface of PP separator to construct LMO@PP composite separator. The composite separator can fully block polysulfides and accelerate its reversible transformation. At 1 C current density, the initial specific discharge capacity of the lithium sulfur batteries assembled with LMO@PP separator reached 904.1mAh /g, and the reversible capacity remained 577.9mAh/g after 500 cycles, and the capacity decay rate was only 0.072%.

(3) LaMnO3 nanosheets materials was prepared by the hydrothermal method and used as the additive of the sulfur/carbon composite cathode materials. The LMO nanosheets have excellent ability of adsorbing polysulfides and catalytic effect on sulfur species. At 1 C current density, the initial specific discharge capacity of the sulfur/carbon composite prepared by adding LMO is 795.9 mAh/g, and the capacity retention rate is high after 100 cycles, and it has good working characteristics.

中图分类号:

 TQ152    

开放日期:

 2023-06-20    

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