| 摘要: | 先前鋰電池研究中發現影響鋰離子電池物性的關鍵主要源於固相電解質介面（Solid Electrolyte Interface，SEI），理想的SEI需要能夠保護電極避免電極與電解質產生不必要的副反應，此外為不阻礙鋰離子的嵌入/嵌出， SEI需要具有良好的離子傳導率才不影響電池之電性。
有鑑於此，本研究探討以特殊改質添加劑複合電場效應並探討其影響SEI 的生成組成以及改善鋰離子電池物性之效果。首先添加劑方面，本實驗以化合物AM與化合物BM進行共聚反應形成高分支網狀結構的添加劑o-AB。組成Li[Ni1/3Mn1/3Co1/3]O2/Li半電池測試，利用電子掃描顯微鏡(SEM)、X-射線光電子光譜(XPS)、循環伏安法(CV)及電化學阻抗頻譜(EIS)進行探討。該實驗數據證實o-AB確實參與SEI的形成且能夠減少電解質的分解並鋰鹽的消耗。透過1%及3% o-AB添加量讓電池電容量經過100圈充放電後從63.3(mAh/g) 分別提升至96.7(mAh/g)及109.1(mAh/g)。
利用電場效應的方式誘導無機物順向排列以增加極片孔洞。由電子掃描顯微鏡(SEM)可以看出外部施加電場的極片孔洞確實增加，除了電解液更易滲入之外也額外提供了鋰離子充放電嵌入/嵌出的管道，使電池充放電過程中活性物質不會遭到破壞，透過電場強度3000、4500及6000(V/cm)作用下 (e3000, e4500, e6000)，100圈充放電循環後電容保持率從60.46%分別提升至89.56% (e3000)、100.76% (e4500)及100.48% (e6000)。
最後我們將添加劑複合電場效應用於鋰離子電池中，希望結合兩項技術優點為鋰離子電池帶來更優越的性能。透過五百圈長圈數測試可以看到，沒有任何修飾的電池在350圈後已經無法進行充放電，而在0% e4500電池經500圈循環後電容保持率僅15.51%。但同時添加劑與電場效應複合應用的1% e3000及3% e3000兩個比例下電容保持率分別提升為52.56%及72.14%。該結果顯示透過電場增加孔道後也讓添加劑更易滲入電極中並讓活性物質更均勻地產生SEI反應，以至於電池能夠長圈數循環後仍能繼續維持良好的電量。
;Previous research on lithium batteries found that the key to the physical properties of lithium-ion batteries mainly stems from the solid electrolyte interface (SEI). The ideal SEI needs to be able to protect the electrode from unnecessary side reactions between the electrode and the electrolyte. In addition, it does not hinder lithium. For the insertion/extraction of ions, SEI needs to have good ionic conductivity so as not to affect the electrical properties of the battery.
In view of this, this study explores the compound electric field effect with special modifying additives and discusses its effect on the formation of SEI and the improvement of the physical properties of lithium-ion batteries. First of all, in terms of additives, in this experiment, the compound AM and the compound BM were copolymerized to form the additive o-AB with a highly branched network structure. Composition Li[Ni1/3Mn1/3Co1/3]O2/Li half-cell test using scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) Discuss. This experiment confirms that o-AB does participate in the formation of SEI and can reduce the decomposition of electrolyte and the consumption of lithium salt. With the addition of 1% and 3%, the battery capacity increased from 63.3 (mAh/g) to 96.7 (mAh/g) and 109.1 (mAh/g) after 100 cycles.
The electric field effect is used to induce the inorganic substances to be arranged in the forward direction to increase the pores of the electrode. It can be seen from the scanning electron microscope (SEM) that the pores of the electrode of the external applied electric field do increase. In addition to the easier penetration of the electrolyte, it also provides an extra diffusion channels for lithium ion to make the active material will not be destroyed in the battery charging and discharging process. Under the action of electric field strength of 3000, 4500 and 6000 (V/cm) (e3000, e4500, e6000), the capacity retention rate increases from 60.46% to 89.56% (e3000), 100.76% (e4500) and 100.48% (e6000) after 100 cycles.
Finally, we apply the additive compound electric field effect to lithium-ion batteries, hoping to combine the two technical advantages to bring better performance to lithium-ion batteries. Through the 500 cycle life test, it can be seen that the battery without any modification can no longer be charged and discharged after 350 cycles, and the capacity retention rate of the 0% e4500 battery after 500 cycles is only 15.51%. But at the same time, the capacity retention rate under the two ratios of 1% e3000 and 3% e3000 for the combined application of the additive and the electric field effect are 52.56% and 72.14%, respectively. The results show that increasing the pores through the electric field also allows the additives to more easily penetrate into the electrode and allows the active material to produce the SEI reaction more uniformly, so that the battery can continue to maintain good power after long cycles. |
