【摘要】：LiMn2O4具有四面體和八面體共同構(gòu)成的三維隧道結(jié)構(gòu)，具有良好的大電流放電性能等優(yōu)勢；但在充放電循環(huán)中其結(jié)構(gòu)易被破壞。本研究，，分別利用構(gòu)建特殊結(jié)構(gòu)和摻雜的方法，對(duì)尖晶石錳酸鋰進(jìn)行了改性，以提高材料的循環(huán)性能。 以檸檬酸為絡(luò)合劑，通過液相反應(yīng)制得前驅(qū)體，然后分步燒結(jié)得到了純相的尖晶石錳酸鋰，并探究了實(shí)驗(yàn)工藝條件對(duì)材料性能的影響；利用聚丙烯酸接枝海綿為模板，制備了海綿狀的錳酸鋰，0.5C倍率下首次充放電電比容量分別為107mAh g-1和98mAh g-1，50次循環(huán)后容量保持率81.6%，循環(huán)得到改善。 分別以Al3+和F-摻雜錳酸鋰。當(dāng)Al3+摻雜量為5%時(shí)材料循環(huán)性能最好，0.3C倍率下材料的首次充放電比容量分別為114.3mAh g-1和104.2mAh g-1，50次循環(huán)后容量保持率為89.5%。實(shí)驗(yàn)發(fā)現(xiàn)摻雜F-并不能改善錳酸鋰的循環(huán)性能。 通過進(jìn)一步Al3+和F-的混合摻雜得到了循環(huán)性能穩(wěn)定的錳酸鋰材料。0.3C電流密度下，摻雜比例為Al7.5%、F2.5%的材料，首次充放電容量分別為121.1mAh g-1和112.2mAh g-1；50次循環(huán)以后，放電比容量為106.9mAh g-1，容量保持率為95.3%。摻雜后放電平臺(tái)平均電壓升高約0.08V，并由原來的雙平臺(tái)變?yōu)橐粋�(gè)，放電變得平穩(wěn)。 通過特殊結(jié)構(gòu)的構(gòu)筑和摻雜，在一定程度上改善了材料的循環(huán)穩(wěn)定性。
[Abstract]:LiMn2O4 has three-dimensional tunnel structure composed of tetrahedron and octahedron, which has good performance of high current discharge, but its structure is easily destroyed in charge-discharge cycle. In this study, special structure and doping methods were used to modify spinel lithium manganate in order to improve the cycling performance of the materials. The precursor was prepared by liquid phase reaction with citric acid as complexing agent, and then the pure phase lithium manganese manganate was obtained by step-by-step sintering, and the effect of experimental conditions on the properties of the material was investigated. The spongy lithium manganate was prepared by using polyacrylic acid grafted sponge as template. The initial charge / discharge specific capacity of lithium manganate at 0.5C ratio was 107mAh / g / 1 and 98mAh / g / 1, respectively. After 50 cycles, the capacity retention rate was 81.6%, and the cycle was improved. Al3 and F-doped lithium manganate were used respectively. When the content of Al3 is 5%, the cyclic performance of the material is the best. The initial charge-discharge specific capacity of the material at 0.3 C ratio is 114.3mAh / g / 1 and 104.2mAh / g / 1, respectively, and the capacity retention rate is 89.5% after 50 cycles. It was found that F-doping could not improve the cycle performance of lithium manganate. The cyclically stable lithium manganate material was obtained by further mixing of Al3 and F -. At 0.3C current density, the doping ratio of Al7.5%,F2.5% was the same as that of lithium manganate. The initial charge-discharge capacity was 121.1mAh g / 1 and 112.2mAh g / 1, respectively. After 50 cycles, the specific discharge capacity is 106.9mAh / g / 1 and the capacity retention rate is 95.3%. After doping, the average voltage of the discharge platform increased about 0.08 V, and changed from two platforms to one, and the discharge became stable. The cyclic stability of the material is improved to a certain extent by the construction and doping of special structure.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM912.9

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