利用常壓電漿對鋰電池負極材料進行氮摻雜以提升其電性表現

Rapid Nitrogen-doping in Lithium-ion Battery Anodes via Atmospheric Pressure Plasma Treatment for Enhanced Electrochemical Performances

莊上毅(Chuang, Shang I)

指導教授 ： 杜正恭

國立清華大學/工學院/材料科學工程學系/碩士(2015年)

摘要

本研究開發常壓電漿產生裝置，將之應用於鋰電池負極材料，期望藉由表面改質，提升電性表現。實驗初期探討大氣電漿束對二維還原氧化石墨烯材料表面處理之影響，由表面化學鍵結及拉曼光譜分析發現，電漿能有效改質表面化學鍵結、引入結構缺陷及進行氮原子摻雜，促使電性提升。經過二十次的電漿處理，在0.5安培/克的充電速度下能有將近每克1500毫安培‧小時的電性表現。
為增加有效的電漿處理面積，再開發了另一套對奈米粉末進行電漿表面改質的常壓介電層電漿產生裝置，同時利用此裝置對二氧化鈦粉末進行表面改質。經過20次的電漿處理，在不同充放電的速度下電性能有20%的提升。電漿可有效於表面摻雜氮原子，而表面鈦原子在過程中被還原，形成氧晶格空缺，大幅提高二氧化鈦的鋰離子傳導速率。
本研究復進行電漿診斷，藉實驗分析電漿中被激發或被游離的高能粒子，並綜合表面分析的結果，探討電漿高能粒子與材料表面的反應過程，以推斷可行之電漿表面改質反應機制。氬及氮激發粒子扮演著產生表面結構缺陷的重要角色。游離氮粒子進而藉由這些結構缺陷摻雜進材料當中。根據本研究成果，常壓電漿可具應用於次世代高效率鋰電池開發之潛力。

關鍵字

常壓電漿 ； 氮摻雜 ； 鋰電池 ； 二氧化鈦 ； 氧化還原石墨稀

並列摘要

The main objective of this dissertation is to develop a rapid surface modification technique to enhance the electrochemical performance of lithium-ion battery (LIB) anodes. Atmospheric pressure plasma jet was constructed to introduce surface treatment to reduced graphene oxide (RGO) 2D electrodes. Result from x-ray photoelectron microscopy suggests a change in surface chemical bonding with increasing plasma treatment repetitions. Plasma also introduce surface defects creating nitrogen-doping. After 20 times of Ar+N2 plasma treatment, a significant increment in cycling property (~1500 mAh/g) under 0.5 A/g was found.
In addition, a specially designed atmospheric dielectric barrier discharge plasma generator that are feasible to modify powders is proposed. The rate capacity of 20 min plasma treated TiO2 anode revealed nearly 20% increment as compared to that of pristine TiO2 at the rates of 0.5, 1, 2, 5, 10 C. As-treated TiO2 was first analyzed by X-ray diffractometer and high resolution transmission electron microscope to confirm that there was no noticeable surface morphology and microstructure change from plasma treatment. In addition, plasma treated TiO2 were reduced before nitrogen-doping were doped with increasing treatment duration.
Significant amount of excited argon (Ar*) and excitation of nitrogen second positive system (N2*) was discovered using optical emission spectroscopy. It was believed that Ar* and N2* contributed to formation of surface defects. After forming defects the decomposed N in the plasma can thus be doped onto the surface of RGO and TiO¬2. Plasma surface modification leads to defect formation as well as nitrogen-doping. By integrating plasma diagnosis and surface characterization, dynamic plasma-surface interaction can thus be proposed to provide further guidelines for plasma surface modifications of LIB anodes. These findings help the understanding of the atmospheric plasma treatment on the surface modification of RGO and TiO2 anode material in Li-ion battery.

並列關鍵字

atmospheric pressure plasma ； nitrogen doping ； lithium-ion battery ； TiO2 ； reduced graphene oxide

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