초록 ▼

◦ 고기능성 (고용량, 고안정성, 고출력) 리튬이차전지 구현을 위한 음극재료 요소기술 개발
1. 스피넬계 Li₄Ti₅O₁₂(LTO)의 제조 및 도핑을 통한 음극 활물질 특성 향상
- 단일상 또는 이종원소 첨가된 LTO 분말 제조 최적 공정 확보
- Al이 첨가 된 LTO의 단일상 입자 확보 및 전기적 특성 분석
- Al과 Ni가 첨가된 LTO 단일상 입자 확보 및 전기적 특성 분석
- ALD를 이용한 AZO 코팅에 따른 전기적 특성 분석
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◦ 고기능성 (고용량, 고안정성, 고출력) 리튬이차전지 구현을 위한 음극재료 요소기술 개발
1. 스피넬계 Li₄Ti₅O₁₂(LTO)의 제조 및 도핑을 통한 음극 활물질 특성 향상
- 단일상 또는 이종원소 첨가된 LTO 분말 제조 최적 공정 확보
- Al이 첨가 된 LTO의 단일상 입자 확보 및 전기적 특성 분석
- Al과 Ni가 첨가된 LTO 단일상 입자 확보 및 전기적 특성 분석
- ALD를 이용한 AZO 코팅에 따른 전기적 특성 분석
- 전자빔 조사를 통한 재료 표면 개질 및 이의 전기화학 특성 평가
2. 금속 촉매 식각법(Metal-assisted chemical etching) 또는 전기화학적 식각법 (Electrochemical etching) 으로 제조된 3차원 구조의 실리콘 음극 재료 제조 및 전기화학적 특성분석
- 지름과 형상에 따른 실리콘 나노구조체 재료의 전기화학적 특성 평가
- 장기 충방전 사이클링 확보를 위한 다양한 바인더의 활용 및 전기화학적 특성 변화 연구
- 표면 처리를 통한 실리콘 표면 전도성 향상 기술개발
- 미세구조 및 전기화학적 특성평가
- 최적 바인더를 이용한 전극제조 공정 개발을 통한 전극 소재 특성 향상

Abstract ▼

In recent years, silicon (Si) has been studied as a new type of anode materials for lithium-ion batteries (LIBs) to replace carbonaceous materials. Large amount of Li could be incorporated into Si leading to an anode capacity of 4,200mAh/g, about 11 times larger than for graphite anodes. However, bu

In recent years, silicon (Si) has been studied as a new type of anode materials for lithium-ion batteries (LIBs) to replace carbonaceous materials. Large amount of Li could be incorporated into Si leading to an anode capacity of 4,200mAh/g, about 11 times larger than for graphite anodes. However, bulk Si anode exhibits a high specific capacity at initial stages, the cycle performance is likely to decay rapidly by pulverization with increasing cycle numbers. More recently, various nanostructured Si anodes have been shown to exhibit excellent performance due to their resistance to fracture and pulverization during volume expansion. To date, one of the most popular methods is vapor-liquid-solid (VLS). With this technique, Si nanowires were adhered to the current collector and additional conducting additives or binder was not required. However, the VLS method for growing Si nanowires thus far is limited in that it is difficult to synthesize large quantities of nanowire material on the substrate and they generally need high temperature and high vacuum.
In this work, we attempted to make a Si nanowire-based electrode using electrochemical and metal-assisted chemical etching method to take advantage of its simple, large-scale, and low-cost. Vertically aligned Si nanowires were fabricated by a mixture of hydrofluoric acid (HF) and an oxidant (H₂O₂) with silver nanoparticles as a catalyst. Before redox reaction, a thick aluminum layer with a thickness of 2 micrometer was deposited on the backside of the wafer to act as a current collector and etch stop material. Also, electrochemical performances were improved by conformal surface coating (carbon, etc.) on Si nanowire templates. The direct fabrication of arrayed or incorporated architectures on the substrate enables fast charge transport, thereby allowing every individual nanostructure to participate in the electrochemical reaction.
Also, Lithium titanate spinel (Li₄Ti₅O₁₂, LTO) is receiving consideration as an anode material for lithium ion battery because of its merit as zero-strain and its stable insertion potential, and long cycle life. However, the major downside of LTO is its low electronic conductivity. To overcome this problem, many studies have been conducted by adding dopants to the LTO powder.
In this study, Li_4-aA_aTi_5-bB_bO_12-cC_c was synthesized by ball milling and calcination methods. Various kinds of doping sources (Ni, Zr, Br, Ag, Zn, Mn, Fe, Co) were added to Li₄Ti₅O₁₂ and treated at different temperatures. The addition of doping elements to Li₄Ti₅O₁₂ is expected to modify the crystal structure, and therefore to change the electrochemical performances of Li₄Ti₅O₁₂.
The structural and morphological properties were measured by XRD(X-ray diffraction) and SEM(scanning electron microscopy). The product is found to consist of single-crystalline nanoparticles with spinel phase and uniform particle sizes in the ranege of 0.5-2 um. Electrochemical performances of LTO and doped LTO are under investigation.