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高性能磷酸盐二次电池电极材料构效关系的研究
胡朴
Thesis Advisor崔光磊
2016-05-25
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Discipline化学工程
Keyword钠离子电池 锂离子电池 锌离子电池 电极材料 磷酸盐
Abstract随着新能源技术的不断发展和应用,开发新型电化学储能技术越来越迫切。本论文围绕二次电池储包括钠离子电池、锂离子电池、锌离子电池等关键材料的磷酸盐电极材料开展了一系列研究,主要包括以下几个部分工作: (1)研究了B掺杂改性磷酸盐电极材料Na3V2P3-xBxO12 (0 ≤ x ≤ 1) 作为钠离子电池正极材料的电化学性能。采用实验和计算相结合的方法揭示了不同B掺杂量样品的晶体结构和电子结构的演化以及Na+储存性能。Na3V2P3-xBxO12 (0 ≤ x ≤ 1/3)呈现略微扭曲的六方晶系Na3V2(PO4)3的结构。精细结构解析和理论计算表明掺杂后材料V-O键长的缩短引起局域结构的改变,带隙变窄,离子迁移势垒降低。电化学性能研究发现,Na3V2P3-1/6B1/6O12样品具有最佳的结构稳定性和电化学性能。 (2)开发了一种新型的V-系磷酸盐钠离子电池负极材料。电化学性能测试发现,在0.05 V- 3.0 V之间循环1 C 可逆容量为146 mAh g-1,通过碳包覆改性后,循环和倍率性能大幅度提高,20 C倍率下可以发挥107 mAh g-1比容量。采用Na3V2(PO4)3/G作为正极组成的全电池表现出优异的循环稳定性,1000 次循环后容量保持80 % 以上。原位XRD测试研究了材料充放电过程中结构演化和反应机制,发现NaV3(PO4)3脱嵌钠的反应过程结构可逆性好、稳定,体积变化率小于10 %。利用Zn2+和Mg2+取代NaV3(PO4)3/C中V2+合成了一系列NaMV2(PO4)3/C (M= Zn, Mg) 复合材料,虽然Zn2+取代的NaZnV2(PO4)3/C样品可逆容量比NaV3(PO4)3/C低,但循环长循环容量保持率明显提高,说明通过离子掺杂可以一定程度上提高材料结构的稳定性。 (3)构建了一个基于磷酸盐Na3V2(PO4)3为正极,Zn为负极,Na+/Zn2+双盐电解液的水系杂化电池。通过优化电解液组成,发现醋酸钠和醋酸锌溶液作为电解液的电化学性能明显优于相应的硝酸盐和硫酸盐电解液。通过不同调整电解液中Na+/Zn2+比例,发现在没有Na+存在的电解液同样具有可逆的电化学性能,建立了一种以NaV2(PO4)3为正极的水系锌离子电池。Na+/Zn2+双盐电解液的杂化电池比纯Zn2+盐电解液具有更好的循环稳定性和倍率性能,由于Zn负极在双盐电解液中更加稳定,有效抑制枝晶生长。 (4)研究了磷酸盐NASICON结构的NaSn2(PO4)3作为锂离子电池负极材料的电化学性能。首次放电过程中,原位生成的Na掺杂的磷酸盐离子导体均匀包覆在Sn纳米颗粒表面,作为优良的保护层阻止了纳米Sn基材料循环过程中团聚和提供了快速电化学反应的离子通道。通过预嵌锂手段,消除首次不可逆容量损失,材料分别与LiFePO4和高电压材料LiNi0.5Mn1.5O4组成全电池,电池表现出优异的倍率性能和循环稳定性,展现出实际应用的可行性。
Other AbstractWith the rapid development of new energy resources and renewable energytechnology, rechargeable electrochemical devices for energy storage have been received growing attention. In this thesis, application of phosphate-based materials in rechargeable batteries, including Na-ion batteries, Li-ion batteries, Zn-based batteries, was evaluated. The concrete research contents are summarized as follows: (1)The electrochemical performance of B substitutedNa3V2P3-xBxO12 (0 ≤ x ≤ 1) as stable cathode materials for Na-ion batterywas investigated. A combined experimental and theoreticalinvestigations on Na3V2P3-xBxO12 (0 ≤ x ≤ 1) were undertaken to reveal the evolution of crystalline and electronic structures and Na storage properties associated with various concentration of B. The crystal structure of Na3V2P3-xBxO12 (0 ≤ x ≤ 1/3) consisted of rhombohedralNa3V2(PO4)3with tiny shrinkage of crystal lattice. Fine structure analysis and the calculated crystal structures suggested that the detailed local structural distortion of substituted materials originated from the slight reduction of V-O distances, the narrow band gap and reduced the lower Na+ diffusion energy barriers.Electrochemical testing demonstrate that Na3V2P3-1/6B1/6O12 significantly enhances the structural stability and electrochemical performance. (2) A vanadium-based orthophosphate, NaV3(PO4)3 has been exploited as a novel anode material for Na-ion batteries. Electrochemical investigation showed that it delivered a high reversible capacity of 146 mAhg-1 at potential range of 0.05 – 3.0 V. A Na-ion full battery with long term cycle life based on NaV3(PO4)3/C anode and Na3V2(PO4)3/C cathode, retaining 80 % of initial capacity after 1000 cycles. The structural revolution and reaction mechanism of NaV3(PO4)3 was evaluated by in-situ XRD, revealing the excellent structural reversibility and stability with small volume expansion (< 10%). A series ofNaMV2(PO4)3/C (M= Zn, Mg) composites were synthesized by replacememt of V2+ with Zn2+ and Mg2+. The substituted materials showed a lower capacity compared to pristine NaV3(PO4)3/C, but exhibited an obviously better capacity retention after long term cycling, demonstrating structural stability could be enhanced by ion doping. (3) Anovel Na+/Zn2+ dual salt aqueous hybrid battery was constructed by using Na3V2(PO4)3 as cathode and metal Zn as anode. It could be found that the battery using sodium acetate and zinc acetate solution as electrolyte exhibited the best electrochemical performance by optimizing the electrolyte composition. The charge/discharge profiles were compared in the electrolyte with various Na+/Zn2+ ratio. NaV2(PO4)3 presents reversible intercalation/deintercation of Zn2+ in Na+ free solution. Thus a prototype of Zn-ion battery was proposed on the bases of NaV2(PO4)3 as cathode and Zn as anode. The cycling stability and rate capability of battery in Na+/Zn2+ dual salt electrolyte were better than that in Zn2+ single salt electrolyte, because the Zn anode was more satble in hybrid electrolyte, effectively inhibiting the dendrite growth. (3) Phosphates, NASICON structured NaSn2(PO4)3were exploited as a novel anode material for Li-ion batteries. Nanoscale Sn was uniformly dispersed in the lithium phosphate matrix during the first discharge. The enhanced properties are attributed to the “in-situ” formation of the ionic conductor as protective matrix, which prevents the aggregation of nanoparticles during the cycling and provides Li+ diffusion channels in the electrode for fast electrochemical reaction. The initial irreversible capacity loss could be eliminated by prelithiation. The obtained material exhibits excellent cycling performance and high rate capabilityfor full cell using LiFePO4 and LiNi0.5Mn1.5O4 as cathode, suggeating the feasibility of practical application.
Department仿生能源与系统团队
Subject Area化学工程
Date Available2018-07-01
Subtype博士 ; 学位论文
Language中文
Document Type学位论文
Identifierhttp://ir.qibebt.ac.cn/handle/337004/9756
Collection仿生与固态能源系统研究组
Affiliation中国科学院青岛生物能源与过程研究所
Recommended Citation
GB/T 7714
胡朴. 高性能磷酸盐二次电池电极材料构效关系的研究[D]. 北京. 中国科学院研究生院,2016.
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