可撓式全固態鋰離子二次電池製作及其特性分析

Abstract

科技日新月異進步，人們對於電子類產品依賴漸漸增加。儲能電池角色為極其重要之一環，著眼於單位體積/重量上儲存之能量密度、功率密度與穩定性，可撓式全固態薄膜鋰離子二次電池被視為具發展潛力指標。此電池具可彎曲、無電解液滲漏、輕量化、壽命長等特性。此應用範圍包括生物機電系統、智慧卡、實驗室晶片、醫學晶 片等。 本研究主要為製作與分析可撓式全固態二次鋰離子電池與新穎氮化釩 (VN) 陽極材料，先以射頻 (RF) 磁控濺鍍陰極鋰鈷氧於具白金薄膜之雲母片上，再濺鍍固態電解質LiPON與以直流 (DC) 磁控濺鍍陽極氮化釩，最終以直流濺鍍鉑金屬作為電流收集器。並以第一 原理計算氮化物之物理特性 (軌域電子能階資訊)。 本研究將探討不同濺鍍條件 (濺鍍功率、濺鍍氣體壓力與濺鍍氣體分率) 與快速退火條件 (退火溫度與退火時間) 對於薄膜組成與結構影響，以X光繞射與電子顯微鏡分別檢測晶體結構與薄膜表面型態，且藉由X光吸收光譜分析薄膜之電子結構。以電化學方面以循環伏安法得知不同電壓下其反應機構，利用交流阻抗測試計算導電度 並另進行電容量測試。

Lithium ion batteries (LIBs) are recognized as new power supplier because of their high energy density, long cycle life, high voltage and safety. With the growth of microelectronic devices, the development of flexible all solid-state thin film batteries (TFBs) is quite important. TFBs has no potentially leak electrolyte which can improve the cycle life significantly and can be integrated into lab-on-chip based devices or smart cards. The purpose of this research is to fabricate the TFBs with the novel vanadium nitride (VN) anode material, lithium phosphorus oxynitride (LiPON) solid electrolyte and lithium cobalt oxide (LiCoO2). The different sputtering parameters were revealed to improve the electrochemical properties of materials and the electronic structure of VN were demonstrated by density functional theory (DFT) which based on first principle calculation. Mica was selected as the substrate due to their flexible, lightweight and excellent chemical stability. The crystal structure and morphology were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The ion conductivity of LiPON was calculated by performing the electrochemical impedance spectroscopy (EIS). The X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) were used to approach the electronic structure of VN. We utilize the cyclic voltammetry (CV) and capacity tester to estimate the electrochemical performance of active materials.