本文選題：軟炭 + 倍率性能�。� 參考：《復(fù)旦大學(xué)》2014年碩士論文

【摘要】：在電動(dòng)汽車領(lǐng)域,汽車電池的能量回收對應(yīng)于電池具有良好的充電倍率性能。而決定鋰離子電池倍率充電性能的是負(fù)極材料。鋰離子負(fù)極材料主要有石墨,軟炭和硬炭。石墨材料是市場應(yīng)用最多的負(fù)極材料,d002在0.3330-0.3370nm,較高的容量和效率,但是在大倍率充電性能差,安全性低。硬炭材料主要是指難石墨化的碳,d002在0.3700-0.400nm,倍率性能和低溫性能較好,但是材料成本高,工藝要求無水無氧環(huán)境,整體的生產(chǎn)成本高。軟炭材料主要指易石墨化碳,d002在0.342-0.347nm,具備較寬的層間距,良好的倍率充放電性能,低溫處于石墨和硬炭之間,材料成本便宜,生產(chǎn)工藝對水氧含量不敏感,已是動(dòng)力電池的發(fā)展方向。但是軟炭在負(fù)極中的應(yīng)用還需要解決如下問題：一是材料的開發(fā),開發(fā)出倍率和低溫性能好的軟炭材料；二是比容量低,壓實(shí)密度低導(dǎo)致的能量密度低；三是工藝的開發(fā),由于軟炭在放電時(shí)的電壓降較大,直流內(nèi)阻大,產(chǎn)生過多的極化熱,造成能量浪費(fèi)。因此軟炭在鋰離子電池中的應(yīng)用開發(fā)任務(wù)還很重。本論文首先考察了不同粒徑的材料具有的倍率性能,材料包覆等方式對低溫性能的改善；混合導(dǎo)電石墨,改善壓實(shí)密度和能量密度；然后在工藝上采取減薄極片尺寸,降低了電池的直流內(nèi)阻。測試了電池各方面的性能,取得了較好的結(jié)果。本論文的主要研究內(nèi)容如下：1.通過比較不同粒徑材料D50=15μm,12μm, 10μm 的 Rs, Rct,發(fā)現(xiàn)倍率性能隨著粒徑的減小而升高,從15μm降低到10μm,Rct減小。減小粒徑能縮短鋰離子在固相里的傳輸路徑,減小電池反應(yīng)阻抗；2.通過瀝青包覆后的軟炭材料的低溫放電能力增強(qiáng),-20℃3C放電比率從未包覆的55%上升到62%,放電平臺(tái)也大幅提高。3.軟炭的首次庫侖效率低,在首次嵌鋰時(shí)消耗大量正極的活性鋰,導(dǎo)致了電池的容量低。通過在負(fù)極表面添加鋰粉,補(bǔ)充了由SEI膜形成和孔隙嵌鋰造成的鋰損失,提高了電池的首次庫侖效率。大大提高了正負(fù)極材料比容量的發(fā)揮：正極比容量發(fā)揮從120mAh/g提高到150mAh/g,負(fù)極比容量從207mAh/g提高到257mAh/g。電池的能量密度提高了近25%。解決了由于軟炭電池首效低等缺陷影響了電池容量發(fā)揮問題。4. 對軟炭材料進(jìn)行工藝優(yōu)化：通過優(yōu)化軟炭粘結(jié)劑,提高了軟炭極片與集流體之間的粘結(jié)強(qiáng)度,提高了電池的倍率性能；通過導(dǎo)電劑的選擇和優(yōu)化,提高了極片的電導(dǎo)率和壓實(shí)密度,增大了電池的體積能量密度,增大了電池的倍率充放電性能。優(yōu)化后的電池具有良好的倍率充放電性能,常溫循環(huán)和大倍率循環(huán)性能,高溫循環(huán)性能和安全性能。
[Abstract]:In the field of electric automobile , the energy recovery of the automobile battery corresponds to the performance of the battery with good charging multiplying power . The lithium ion negative electrode material mainly refers to graphite , soft carbon and hard carbon . The graphite material is mainly graphite , soft carbon and hard carbon .
secondly , the energy density caused by low specific capacity and low compaction density is low ;
Third is the development of the process , because the voltage drop of the soft carbon in the discharge is large , the direct current internal resistance is large , excessive polarization heat is generated , and energy waste is caused . Therefore , the application development task of the soft charcoal in the lithium ion battery is also very heavy .
mixing conductive graphite to improve compaction density and energy density ;
The results are as follows : 1 . By comparing Rs and Rct of different particle size materials D50 = 15 渭m , 12 渭m , 10 渭m , the rate performance is decreased from 15 渭m to 10 渭m , and Rct is reduced . The reduction of particle size can shorten the transmission path of lithium ion in solid phase and decrease the reaction impedance of the battery .
2 . the low - temperature discharge capacity of the soft carbon material after the asphalt coating is enhanced , the 3C discharge ratio of -20 DEG C is increased from 55 % to 62 % , and the discharging platform is greatly improved . By optimizing the soft carbon binder , the bonding strength between the soft carbon pole piece and the current collector is improved , and the multiplying power performance of the battery is improved ;
Through the selection and optimization of the conductive agent , the electrical conductivity and the compaction density of the pole pieces are improved , the volume energy density of the battery is increased , and the rate and discharge performance of the battery is increased .

【學(xué)位授予單位】：復(fù)旦大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM912

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

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本文編號(hào)：1874769