鋰離子電池銅集流體表面功能結(jié)構(gòu)設(shè)計(jì)、加工及性能分析
發(fā)布時(shí)間：2018-07-31 05:27
【摘要】：作為移動(dòng)電子設(shè)備、電動(dòng)工具、電動(dòng)汽車(chē)等的電源以及在工業(yè)儲(chǔ)能方面的巨大潛力，，鋰離子電池引人注目。鋰離子電池的廣泛應(yīng)用，對(duì)其性能提出了更高的要求，推動(dòng)了高容量負(fù)極材料的發(fā)展。但是，高容量負(fù)極材料在實(shí)際應(yīng)用中受到諸多限制，因?yàn)樵谂c鋰離子的合金化和脫合金過(guò)程中，其體積發(fā)生嚴(yán)重變化，致使電極材料粉化、與銅集流體之間發(fā)生脫離，電極結(jié)構(gòu)被破壞，鋰離子電池容量快速衰減。針對(duì)這個(gè)問(wèn)題，本文提出具有表面功能結(jié)構(gòu)的高性能新型銅集流體，圍繞結(jié)構(gòu)的設(shè)計(jì)、成形、作用機(jī)理及對(duì)鋰離子電池循環(huán)性能的影響展開(kāi)系統(tǒng)研究，主要研究工作如下： 1.高容量負(fù)極材料粉化失效的數(shù)學(xué)模型 基于線(xiàn)彈性材料的基本假定，根據(jù)鋰離子電池中鋰離子在負(fù)極材料中的擴(kuò)散規(guī)律，分析電極材料中應(yīng)力的產(chǎn)生機(jī)理。將鋰離子在負(fù)極材料中擴(kuò)散引起的膨脹等效成熱膨脹，通過(guò)對(duì)電極材料膨脹時(shí)的力學(xué)分析，得出了電極材料中應(yīng)力的函數(shù)。根據(jù)線(xiàn)彈性材料脆性斷裂的K準(zhǔn)則，討論了電極材料的斷裂失效，得出了決定材料失效的關(guān)鍵函數(shù)，即高容量負(fù)極材料粉化失效的數(shù)學(xué)模型。 2.銅集流體表面結(jié)構(gòu)設(shè)計(jì)及數(shù)學(xué)模型 根據(jù)材料粉化失效模型，當(dāng)鋰離子在電極材料中擴(kuò)散時(shí)會(huì)有內(nèi)應(yīng)力產(chǎn)生。為了避免內(nèi)應(yīng)力導(dǎo)致的電極材料失效，提出銅集流體表面微盲孔結(jié)構(gòu)及微球結(jié)構(gòu)。結(jié)構(gòu)對(duì)電極材料的體積變化有較好的約束，即可以提供良好的力學(xué)環(huán)境來(lái)抑制電極材料的膨脹。根據(jù)結(jié)構(gòu)應(yīng)滿(mǎn)足的約束條件，建立了表面微盲孔結(jié)構(gòu)及微球結(jié)構(gòu)的數(shù)學(xué)模型。分析表明：同種孔形，深寬比越大，材料受到孔的約束就越大，限制膨脹的效果就越好；不同孔形，相同深寬比的情況下，錐形孔、圓柱形孔及球形孔的功能依次增強(qiáng)。微球結(jié)構(gòu)的數(shù)學(xué)模型與球形孔的模型相同，理論上兩種結(jié)構(gòu)在抑制電極材料膨脹上的作用相同。 3.微盲孔結(jié)構(gòu)激光加工成形、微球結(jié)構(gòu)燒結(jié)成形 采用激光技術(shù)制備具有微盲孔結(jié)構(gòu)的銅集流體。針對(duì)激光光束移動(dòng)的特點(diǎn)，本文提出光束同心圓掃描——光束定點(diǎn)的加工方案，在一定程度上提高了打孔的質(zhì)量。實(shí)驗(yàn)結(jié)果表明：當(dāng)激光輸出功率、激光掃描速度、激光脈沖重復(fù)頻率及激光光束離焦量分別取20W、500mm/s、20kHz、10μm時(shí)，可以得到較好的孔形。 采用固相燒結(jié)技術(shù)制備表面微球結(jié)構(gòu)銅集流體，制定了球形銅粉顆粒與板狀銅集流體的燒結(jié)工藝。結(jié)果表明：在燒結(jié)時(shí)間及銅粉粒徑不變的情況下，燒結(jié)溫度與燒結(jié)頸的大小成正比，即燒結(jié)溫度越高燒結(jié)頸越大，燒結(jié)強(qiáng)度就越高；在銅粉顆粒粒徑及燒結(jié)溫度不變時(shí)，燒結(jié)時(shí)間越長(zhǎng)，燒結(jié)頸就越大，燒結(jié)強(qiáng)度就越高。得出：燒結(jié)溫度為1000℃，燒結(jié)時(shí)間為3h時(shí)，各粒徑銅粉與銅集流體之間的燒結(jié)強(qiáng)度最大，為最佳的燒結(jié)工藝。 4.銅集流體性能測(cè)試、高容量硅負(fù)極鋰離子電池性能測(cè)試 通過(guò)循環(huán)伏安實(shí)驗(yàn)、接觸角測(cè)試及拉伸實(shí)驗(yàn)分別研究了銅集流體的電化學(xué)性能、表面潤(rùn)濕性及力學(xué)性能。結(jié)果表明：表面具有結(jié)構(gòu)的銅集流體在電解液中性質(zhì)穩(wěn)定，作為負(fù)極集流體時(shí)負(fù)極電壓不得高于3.5V vs. Li+/Li；表面結(jié)構(gòu)對(duì)銅集流體的親水性影響不大；表面微盲孔結(jié)構(gòu)銅集流體的抗拉強(qiáng)度可以滿(mǎn)足要求，表面微球結(jié)構(gòu)銅集流體的抗拉強(qiáng)度偏低。 通過(guò)充放電循環(huán)實(shí)驗(yàn)，測(cè)試表面微盲孔結(jié)構(gòu)及微球結(jié)構(gòu)銅集流體制備的高容量硅負(fù)極鋰離子電池的性能。結(jié)果表明這兩種結(jié)構(gòu)可以提供高效的約束力來(lái)抑制電極材料的膨脹，改善鋰離子電池的性能。微盲孔的結(jié)構(gòu)參數(shù)對(duì)鋰離子電池的性能有一定的影響：同一孔徑下，孔越深性能越好；同一深度下，孔徑小的表現(xiàn)出的性能好。對(duì)于微球結(jié)構(gòu)銅集流體，隨著微球粒徑的增大，鋰離子電池的性能表現(xiàn)逐漸變好，即大粒徑微球結(jié)構(gòu)更具優(yōu)勢(shì)。
[Abstract]:Lithium ion batteries are attractive as power sources for mobile electronic equipment, electric tools, electric vehicles, and in industrial energy storage. Lithium-ion batteries are attracting more and more attention. The wide application of lithium ion batteries has put forward higher requirements for its performance and promoted the development of high capacity negative electrode materials. However, high capacity negative electrode has been widely used in practical applications. Restriction, because in the process of alloying and dealloying with lithium ion, the volume of the electrode is changed seriously, the electrode material is pulverized, the electrode structure is broken, the electrode structure is destroyed and the capacity of lithium ion battery is fast attenuated. Structural design, forming, mechanism of action and its effect on cycle performance of lithium-ion batteries are systematically studied. The main research work is as follows:
A mathematical model for the pulverization failure of 1. high capacity negative electrode materials
Based on the basic assumption of linear elastic material, according to the diffusion law of lithium ion in the anode material of lithium ion battery, the mechanism of the stress in the electrode material is analyzed. The expansion of the lithium ion in the negative material is equivalent to the thermal expansion. The stress in the electrode material is obtained by the mechanical analysis of the expansion of the electrode material. According to the K criterion of brittle fracture of linear elastic material, the fracture failure of electrode material is discussed, and the key function of material failure is obtained, that is, the mathematical model of high capacity negative material pulverization failure.
Surface structure design and mathematical model of 2. copper collecting fluid
According to the failure model of material powder, the internal stress is produced when the lithium ion diffusion in the electrode material. In order to avoid the failure of the electrode material caused by the internal stress, the micro blind hole structure and the microsphere structure of the copper collector surface are put forward. The structure has a good constraint on the volume change of the electrode material, that is, a good mechanical environment can be provided to suppress the electricity. The expansion of polar materials. Based on the constraint conditions that the structure should satisfy, a mathematical model for the structure of the micro blind hole and the structure of the microsphere is established. The analysis shows that the larger the ratio of the depth to width, the greater the ratio of the hole to the material, the better the effect of the expansion is, the conical hole, the cylindrical hole and the ball in the case of the same hole shape, the same depth and width ratio. The mathematical model of the microsphere structure is the same as that of the spherical pore, and the effect of the two structures on restraining the expansion of electrode material is the same in theory.
3. micro blind hole structure laser forming, microsphere structure sintering forming
Laser technology is used to prepare copper collector with micro blind hole structure. Aiming at the characteristics of laser beam movement, this paper proposes a beam concentric circle scanning, the processing scheme of the beam fixed point, to a certain extent the quality of the perforation is improved. The experimental results show that the laser output power, the laser scanning speed, the laser pulse repetition frequency and the excitation are shown. When the light beam defocus is 20W, 500mm/s, 20kHz, and 10 m, good aperture shape can be obtained.
The solid phase sintering technology was used to prepare the surface microsphere copper collector, and the sintering process of spherical copper powder particles and plate shaped copper collector was made. The results show that the sintering temperature is proportional to the size of the sintered neck, that is, the higher the sintering temperature, the higher the sintering neck and the higher the sintering strength. When the particle size and sintering temperature are constant, the longer the sintering time, the larger the sintering neck and the higher the sintering strength. It is concluded that the sintering temperature is 1000, and the sintering time is 3h, the sintering strength between the copper powder and the copper collector is the best, which is the best sintering process.
4. copper collector performance test, high capacity silicon negative electrode lithium ion battery performance test
The electrochemical properties, surface wettability and mechanical properties of copper collector fluid are studied by cyclic voltammetry, contact angle test and tensile test. The results show that the properties of the copper collector on the surface are stable in the electrolyte, and the negative electrode voltage is not higher than 3.5V vs. Li+/Li when the negative electrode is used as a negative collector; the surface structure is to the copper collector. The hydrophilicity of the copper collector has little effect, the tensile strength of the copper collector with the surface micro-blind hole structure can meet the requirements, and the tensile strength of the copper collector with the surface micro-sphere structure is low.
The performance of the high capacity silicon negative lithium ion battery prepared by the micro blind hole structure and the microsphere structure copper collector is tested by the charge discharge cycle experiment. The results show that the two structures can provide effective binding to suppress the expansion of the electrode materials and improve the energy of the lithium ion batteries. The performance has a certain influence: the deeper the hole is, the better the performance of the hole, the better the performance of the small aperture at the same depth. For the microsphere structure copper collector, the performance of the lithium ion battery becomes better with the increase of the particle size, that is, the structure of the large particle size microsphere is more advantageous.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TM912
本文編號(hào)：2154565
[Abstract]:Lithium ion batteries are attractive as power sources for mobile electronic equipment, electric tools, electric vehicles, and in industrial energy storage. Lithium-ion batteries are attracting more and more attention. The wide application of lithium ion batteries has put forward higher requirements for its performance and promoted the development of high capacity negative electrode materials. However, high capacity negative electrode has been widely used in practical applications. Restriction, because in the process of alloying and dealloying with lithium ion, the volume of the electrode is changed seriously, the electrode material is pulverized, the electrode structure is broken, the electrode structure is destroyed and the capacity of lithium ion battery is fast attenuated. Structural design, forming, mechanism of action and its effect on cycle performance of lithium-ion batteries are systematically studied. The main research work is as follows:
A mathematical model for the pulverization failure of 1. high capacity negative electrode materials
Based on the basic assumption of linear elastic material, according to the diffusion law of lithium ion in the anode material of lithium ion battery, the mechanism of the stress in the electrode material is analyzed. The expansion of the lithium ion in the negative material is equivalent to the thermal expansion. The stress in the electrode material is obtained by the mechanical analysis of the expansion of the electrode material. According to the K criterion of brittle fracture of linear elastic material, the fracture failure of electrode material is discussed, and the key function of material failure is obtained, that is, the mathematical model of high capacity negative material pulverization failure.
Surface structure design and mathematical model of 2. copper collecting fluid
According to the failure model of material powder, the internal stress is produced when the lithium ion diffusion in the electrode material. In order to avoid the failure of the electrode material caused by the internal stress, the micro blind hole structure and the microsphere structure of the copper collector surface are put forward. The structure has a good constraint on the volume change of the electrode material, that is, a good mechanical environment can be provided to suppress the electricity. The expansion of polar materials. Based on the constraint conditions that the structure should satisfy, a mathematical model for the structure of the micro blind hole and the structure of the microsphere is established. The analysis shows that the larger the ratio of the depth to width, the greater the ratio of the hole to the material, the better the effect of the expansion is, the conical hole, the cylindrical hole and the ball in the case of the same hole shape, the same depth and width ratio. The mathematical model of the microsphere structure is the same as that of the spherical pore, and the effect of the two structures on restraining the expansion of electrode material is the same in theory.
3. micro blind hole structure laser forming, microsphere structure sintering forming
Laser technology is used to prepare copper collector with micro blind hole structure. Aiming at the characteristics of laser beam movement, this paper proposes a beam concentric circle scanning, the processing scheme of the beam fixed point, to a certain extent the quality of the perforation is improved. The experimental results show that the laser output power, the laser scanning speed, the laser pulse repetition frequency and the excitation are shown. When the light beam defocus is 20W, 500mm/s, 20kHz, and 10 m, good aperture shape can be obtained.
The solid phase sintering technology was used to prepare the surface microsphere copper collector, and the sintering process of spherical copper powder particles and plate shaped copper collector was made. The results show that the sintering temperature is proportional to the size of the sintered neck, that is, the higher the sintering temperature, the higher the sintering neck and the higher the sintering strength. When the particle size and sintering temperature are constant, the longer the sintering time, the larger the sintering neck and the higher the sintering strength. It is concluded that the sintering temperature is 1000, and the sintering time is 3h, the sintering strength between the copper powder and the copper collector is the best, which is the best sintering process.
4. copper collector performance test, high capacity silicon negative electrode lithium ion battery performance test
The electrochemical properties, surface wettability and mechanical properties of copper collector fluid are studied by cyclic voltammetry, contact angle test and tensile test. The results show that the properties of the copper collector on the surface are stable in the electrolyte, and the negative electrode voltage is not higher than 3.5V vs. Li+/Li when the negative electrode is used as a negative collector; the surface structure is to the copper collector. The hydrophilicity of the copper collector has little effect, the tensile strength of the copper collector with the surface micro-blind hole structure can meet the requirements, and the tensile strength of the copper collector with the surface micro-sphere structure is low.
The performance of the high capacity silicon negative lithium ion battery prepared by the micro blind hole structure and the microsphere structure copper collector is tested by the charge discharge cycle experiment. The results show that the two structures can provide effective binding to suppress the expansion of the electrode materials and improve the energy of the lithium ion batteries. The performance has a certain influence: the deeper the hole is, the better the performance of the hole, the better the performance of the small aperture at the same depth. For the microsphere structure copper collector, the performance of the lithium ion battery becomes better with the increase of the particle size, that is, the structure of the large particle size microsphere is more advantageous.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TM912
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