本文選題：鋰-硫電池 + 隔膜涂層��； 參考：《北京化工大學(xué)》2016年碩士論文

【摘要】：鋰-硫電池因其高的理論比能量,使它成為滿足能源需求的儲(chǔ)能材料中最有希望的候選者之一。但金屬鋰作為鋰-硫電池的負(fù)極,存在生長枝晶、粉化、多硫化鋰“穿梭”造成的鋰負(fù)極腐蝕等問題,導(dǎo)致低的庫倫效率和循環(huán)壽命,并存在安全隱患。針對(duì)于此,本文創(chuàng)新性的將隔膜涂層改性與鋰負(fù)極保護(hù)有機(jī)結(jié)合,以期鋰負(fù)極具有穩(wěn)定的表面,進(jìn)而提高鋰-硫電池的電化學(xué)性能。具體進(jìn)行了以下研究工作：1、成功地制備了保護(hù)鋰負(fù)極的聚偏氟乙烯(PVDF)隔膜涂層,考察了其對(duì)鋰-硫電池性能的影響,并揭示了其影響規(guī)律。結(jié)果表明,PVDF涂層厚度僅為2.5μm時(shí),在200mA/g充放電電流密度下,首次放電比容量可達(dá)1173mAh/g,循環(huán)80次后仍能保持722mAh/g,平均庫倫效率可達(dá)99%。SEM測試循環(huán)后的鋰負(fù)極表面發(fā)現(xiàn),硫含量很低,且未見明顯腐蝕,進(jìn)一步證明了面向鋰負(fù)極的PVDF隔膜涂層可以減少充放電過程中多硫化物的穿梭,抑制鋰枝晶生長,從而實(shí)現(xiàn)對(duì)鋰負(fù)極的保護(hù)。2、首次設(shè)計(jì)制備了LiNO3/Al2O3/PVDF復(fù)合隔膜涂層,通過Al2O3/ PVDF的雙重作用及LiNO3的緩釋,有效地增強(qiáng)了隔膜涂層對(duì)鋰負(fù)極的保護(hù),進(jìn)一步提高了鋰-硫電池的比容量、循環(huán)性能、倍率性能。在200mA/g充放電電流密度下,首次放電比容量提高到1283mAh/g,循環(huán)100次后比容量仍有712mAh/g,且鋰負(fù)極表面形貌保持穩(wěn)定,元素硫的附著大大減少。且證明了隔膜該涂層可降低了電池內(nèi)阻和極化現(xiàn)象,減少了電解液與鋰負(fù)極之間的副反應(yīng),抑制了枝晶生長。3、對(duì)鋰負(fù)極保護(hù)用有機(jī)硅聚二甲基硅氧烷(PDMS)隔膜涂層的制備及性能進(jìn)行了探索。實(shí)現(xiàn)了在200mA/g充放電電流密度下,首次放電比容量為1043mAh/g,100次循環(huán)后比容量為818mAh/g,容量保持率提高到78%,有效地提高了電池的循環(huán)穩(wěn)定性。通過充放電測試發(fā)現(xiàn),PDMS涂層可減小極化作用,提高電化學(xué)活性,阻隔多硫離子穿梭,抑制鋰枝晶生長,進(jìn)而保護(hù)鋰負(fù)極。這一結(jié)果未見文獻(xiàn)報(bào)道。
[Abstract]:Because of its high theoretical specific energy, lithium-sulfur battery has become one of the most promising candidates for energy storage materials.However, as the negative electrode of lithium-sulfur battery, there are problems such as dendrite growth, pulverization, lithium negative corrosion caused by lithium polysulfide "shuttle", which lead to low Coulomb efficiency and cycle life, and there are hidden dangers of safety.In order to improve the electrochemical performance of lithium-sulfur battery, this paper innovatively combines the membrane coating modification with lithium negative electrode protection to ensure that the lithium anode has a stable surface.In this paper, the following research work was carried out: 1. The PVDF membrane coating was successfully prepared to protect the lithium negative electrode. The effect of PVDF membrane coating on the performance of lithium-sulfur battery was investigated, and the effect of the coating on the performance of lithium-sulfur battery was revealed.The results show that when the thickness of the 200mA/g coating is only 2.5 渭 m, the initial discharge specific capacity can reach 1173 mg / g at the current density of 200mA/g charge / discharge, and the initial discharge specific capacity can be maintained at 722 mg / g after 80 cycles. The average Coulomb efficiency can reach to the surface of the lithium anode after the 99%.SEM test cycle, and the sulfur content is very low.No obvious corrosion was observed, which further proved that the PVDF film coating for lithium anode can reduce the shuttle of polysulfide during charge and discharge, and inhibit the growth of lithium dendrite.The LiNO3/Al2O3/PVDF composite diaphragm coating was designed and fabricated for the first time. By the dual action of Al2O3/ PVDF and the slow release of LiNO3, the protective effect of the diaphragm coating on the lithium negative electrode was effectively enhanced, and the specific capacity of the lithium-sulfur battery was further improved.Cycle performance, rate performance.At 200mA/g charge / discharge current density, the first discharge capacity is increased to 1283 mAh/ g, the specific capacity is still 712mAh/ g after 100 cycles, and the surface morphology of lithium anode remains stable, and the adhesion of elemental sulfur is greatly reduced.It is proved that the coating can reduce the internal resistance and polarization of the battery and reduce the side reaction between the electrolyte and the lithium anode.The dendritic growth was inhibited. The preparation and properties of silicone polydimethylsiloxane (PDMS) membrane coating for lithium negative electrode protection were investigated.Under the charge / discharge current density of 200mA/g, the first discharge specific capacity is 1043mAh/ g / g and the specific capacity is 818mAh/ g after 100 cycles, and the capacity retention rate is increased to 78g, which effectively improves the cycle stability of the battery.By charge-discharge test, it was found that PDMS coating can reduce polarization, improve electrochemical activity, block polysulfide ion shuttle, inhibit the growth of lithium dendrite, and then protect lithium negative electrode.This result is not reported in the literature.
【學(xué)位授予單位】：北京化工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TM912

【參考文獻(xiàn)】

相關(guān)期刊論文 前2條

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本文編號(hào)：1764373