Development of Mn-based cathode materials for lithium secondary battery : リチウム二次電池用マンガン系正極材料の開

이윤성 Graduate School of Science Engineering Saga Univer 2001 해외박사

Among the intercalation materials, lithiated transition metal oxides such as LiMO_(2) (M = Co, Ni, Mn) and LiMn_(2)O_(4) have been widely studied as the cathode materials for lithium secondary batteries. In order to produce commercially viable rechargeable lithium batteries, it is desirable to concentrate on the research of cathode materials. This is an absolute key issue in developing for new and better lithium secondary battery system because approximately 40% of the weight of a cell is associated with the cathode. Therefore, this work is focused on development of cathode materials for lithium secondary battery and it contributes as follows: 1) LiMn_(2)O_(4) has been synthesized at different calcination temperatures using the melt-impregnation method. LiMn_(2)O_(4) cells calcined at lower temperatures (700-800℃) showed excellent cycling performances at room temperature until 50 cycles. However, LiMn_(2)O_(4) cells calcined at higher temperature (850-900℃) exhibited abrupt capacity loss and very small discharge capacities in the 4 V region. It resulted from oxygen deficiency of LiMn_(2)O_(4) spinel structure over 800 ℃ and showed a large value of 3.2 V plateau in the discharge curve. We found that the 3.2 V plateau showed a very clear relation with the oxygen deficiency and represented the degree of oxygen deficiency in the spinel structure. 2) LiM_(x)Mn_(2-x)O_(4) (M = Co, Ni) were synthesized using γ-MnOOH source with various doping contents (0.0-0.5). All compounds showed a pure single phase except the LiNi_(0.5)Mn_1.5O_(4) compound in the XRD patterns. Metal-doped spinels have a smaller crystallite size and higher strain than that of the pure LiMn_(2)O_(4). Although Co and Ni doping materials showed a slightly different cycle behavior because these materials retained different average oxidation numbers, all materials which synthesized usingγ-MnOOH source presented unique cycling characterization in the (3+4) V region. 3) LiAl_(x)Mn_(2-x)O_(4) has been synthesized using various aluminum starting materials, such as Al(NO_(3))_(3), Al(OH)_(3), AlF_(3) and Al_(2)O_(3) at 800 ℃ for 20 h in air or oxygen atmosphere. A melt-impregnation method was used to synthesize Al-doped spinel with good battery performance in this research. The Al-doped content and the intensity ratio of (311)/(400) peaks can be important parameters in synthesizing Al-doped spinel which satisfies the requirements of high discharge capacity and good cycleability at the same time. The decrease in Mn^(3) ion by Al substitution induces a high average Mn oxidation state in the LiAl_(x)Mn_(2-x)O_(4) material. The electrochemical behavior of all samples was studied in Li/LiPF_6-EC/DMC(1:2 by vol.)/LiAl_xMn_(2-x)O_(4) cells. Especially, the initial and last discharge capacity of LiAl_(0.09)Mn_(1.97)O_(4) using LiOH, Mn_(3)O_(4) and Al(OH)_(3) complex were 128.7 mAh/g and 115.5 mAh/g after 100 cycles, respectively. Furthermore, it exhibited an excellent cycling performance even though at high temperature test (□60 ℃). The Al substitution in LiMn_(2)O_(4) was an excellent method of enhancing the cycleability of stoichiometric LiMn_(2)O_(4) spinel during electrochemical cycling. From the many sorts of electrochemical experiments and cycling test, we found some unique characterizations of Al-doped spinel (LiAl(0.1)Mn_(1.9)O_(4)) in the various voltage region. 4) LiMn_(2)O_(4) and LiAl_(0.1)Mn_(1.9)O_(4) were synthesized using LiOH, Al(NO_(3))_(3), and Mn_(3)O_(4). LiAl_(0.1)Mn_(1.9)O_(4) showed an excellent cycling performance in the 4 V region, but it produced an abrupt capacity loss compared to that of LiMn_(2)O_(4) spinel in the 3 V region. From ex-situ XRD measurements, it was observed that the intensities of (311) and (400) peaks for LiAl_(0.1)Mn_(1.9)O_(4), which are typical peaks of cubic phase, gradually increases with the cycling and indicated the formation of mixed structure of distinct cubic and tetragonal phases after the 3rd cycle. It was found that the increase of cubic phase in LiAl_(0.1)Mn_(1.9)O_(4) structure prevented complete structural change from cubic (Li_1.0Mn_(2)O_(4)) to tetragonal (Li_(2)Mn_(2)O_(4)) in the 3 V region. This phenomenon might be considered to be one of major origins which induced a severe capacity loss for LiAl_(0.1)Mn_(1.9)O_(4) material in the 3 V region. 5) LiMn_(2)O_(4) and LiAl_(0.1)Mn_(1.9)O_(4) and materials were synthesized using LiOH, Al(NO_(3))_(3), and different Mn sources (Mn_(3)O_(4) and γ-MnOOH). XRD patterns showed that all the prepared materials had the same identical crystalline phase (Fd3^(―) m). Two materials using the Mn_(3)O_(4) source exhibited quite different cycle characteristics depending on the cycling voltage range. However, the two materials using theγ-MnOOH source showed an identical cycling performance in both the 3 V and 4 V regions. A transmission electron microscope (TEM) analysis revealed that the materials usingγ-MnOOH consisted of two kinds of structures of cubic and tetragonal in the resulting powders although these were shown as a pure cubic spinel structure in the XRD diagram. This indicated a more stable state for the two Mn-based materials usingγ-MnOOH when the transformation from the cubic to tetragonal phase occurred in the 3 V region. Furthermore, we also found that two LiAl_(0.1)Mn_(1.9)O_(4) materials using Mn_(3)O_(4) and γ?MnOOH sources showed different XRD patterns discharged down to 2.2 V after 50 cycles. LiAl_(0.1)Mn_(1.9)O_(4) materials using Mn_(3)O_(4) showed mixed cubic and tetragonal phase after 50 cycles. Meanwhile, it was observed that LiAl_(0.1)Mn_(1.9)O_(4) synthesized usingγ-MnOOH has a majority of tetragonal phase after 50 cycles under the same test conditions and had a higher capacity retention rate in the 3 V region. We firstly report that many extraordinary electrochemical performances of the two LiAl_(0.1)Mn_(1.9)O_(4) materials which prepared using different manganese sources. 6) Orthorhombic LiMnO_(2) was synthesized using LiOH andγ-MnOOH starting materials at 1000 ℃ in an argon atmosphere by quenching method. XRD diagram revealed the LiMnO_(2) compound in this study showed a well-defined orthorhombic phase of a space group with Pmnm. The lattice constants of resulting compound were a = 2.806 Å, b = 5.750 Å, and c = 4.593 Å. The compound was composed of particles of about 5-15μm diameter with a bar-shape and small spherical one of about 1?2μm. After grinding, LiMnO_(2) compound delivered 201 mAh/g in the first cycle and still delivered 200 mAh/g after 50 cycles at room temperature. We confirmed that the initial discharge capacity of LiMnO_(2) agreed well with its specific surface area. The well-defined orthorhombic LiMnO_(2) made by the quenching method exhibited an excellent cycle performan

STUDY OF SUPERSONIC, DUAL, COAXIAL, SWIRLING JET

이권희 Graduate School of Science and Engineering Saga Un 2004 해외박사

일반적으로 초음속 제트유동은 고압의 기체를 오리피스나 노즐을 통하여 방출시킬 때 발생하며, 비상체의 추진, 공기블라스트 가공, 금속분말 제조, 램젯엔진 설계, 초음속 연소기 설계 등 다양한 산업분야에 응용되어지고 있다. 지금까지 초음속 단일제트(supersonic single jet)에 관해서는 많은 연구가 수행되어져 중요한 물리적 현상, 즉, 노즐의 압력비가 알려지는 경우, 제트에서 발생하는 충격파 구조, 제트코어, 제트폭 그리고 마하디스크의 위치 및 직경 등, 은 매우 잘 알려져 있다. 그러나 엔진 초음속 연소실 설계, 추진기 성능향상 및 소음 저감설계등에 응용되어지는 초음속 동축 자유제트에 관한 연구보고서는 많지 않으며, 효율적인 동축노즐 설계를 위한 데이타는 많이 알려져 있지 않다. 특히 제트연소실 성능향상 및 화염제어, 램젯엔진 설계, 유동의 혼합성능증진 등에 응용되어지는 초음속 이중 스월 제트에서 환형 이차 유동의 특성이 동축 스월 제트특성에 미치는 영향에 관한 연구보고서는 거의 없는 실정이다. 그것은 동축제트 특성에 영향을 미치는 많은 변수들과 복잡성으로 인해 해석 및 실험에 어려움이 있기 때문으로 생각되어 진다. 그러나 초음속 이중 동축 노즐의 실제적인 응용 및 설계를 위해서는 이에 관한 체계적인 연구가 요구되어 진다. 따라서 본 연구에서는 초음속 이중 동축제트에서 노즐 압력비, 환형 이차 스월 제트, 노즐형상등의 영향을 실험 및 수치계산의 방법으로 조사 규명하였다. 이를 위하여 본 연구는 크게 3분야로 나뉘어져 이루어 졌다. 첫째, 초음속 이중 동축 제트에서 이차환형 유동(Secondary Annular Stream)이 스월을 수반하는 경우, 주제트(Primary Jet)의 충격파 구조, 유동장내 압력분포등에 미치는 영향을 실험 및 수치해석을 통하여 규명하였다. 또한 이중 동축 노즐 형상, 노즐 두께 및 이차제트 두께 등이 제트구조에 미치는 영향을 조사하였다. 둘째, 초음속 이중 동축 제트에서 내부제트(Primary Jet) 및 이차환형제트(Secondary Annular Jet)가 모두 스월을 가지는 경우로, 두제트의 압력비, 스월의 방향, 노즐두께 및 이차제트 두께가 연소기내에서 화염의 안정에 큰 영향을 미치는 순환영역(Recirculation region) 및 압력분포 특성에 미치는 영향을 상세하게 실험적으로 조사하였다. 특히 위 연구과정에서 노즐 내부형상이 스월 제트유동 특성에 큰 영향을 미침을 확인하고 보충 연구를 수행하였다. 이것은 압축성 스월제트 연구분야에서 처음으로 시도된 연구라고 생각되어 진다. 셋째, 일반적으로 초음속 제트 연구에서 초음속 노즐의 내부형상(노즐 목 상류)은 주요한 변수로 고려되지 않았다. 초음속 자유제트특성은 노즐 압력비(노즐 내부 및 노즐 출구 압력비)가 알려지면 주요특성은 결정되어지는 것으로 잘 알려져 있다. 그러나 본 연구를 통하여 초음속 스월 제트의 경우, 노즐 내부형상을 초음속 스월제트구조에 큰 영향을 미친다는 것을 알았으며, 노즐 내부 형상을 이용한 초음속 스월 분류의 제어가능성의 방법을 확인하였다. 이러한 연구는, 연구자의 지식에 의하면, 처음으로 발표되어지는 것이다.

Ring-opening polymerization of 2-Aryl-1-methylenecyclopropanes catalyzed by Pd complexes

김선욱 Graduate School of Science and Engineering Tokyo i 2002 해외박사

In this thesis, the author has described the ring-opening polymerization and copolymerization of 2-aryl-l-methylenecyclopropanes by Pd complexes to give the polymers with novel structures. In Chapter 2, the author has demonstrated the systematic study on the ring-opening polymerization of 2-aryl-1-methylenecyclopropanes catalyzed by palladium complexes having various diimine ligands. Palladium complexes with diimine ligands catalyze ring-opening polymerization of 2-phenyl-1-methylenecyclopropane to give a polymer with Mn of up to 11,000. The polymer consists of a well-regulated head-to-tail sequence of -CH_2-C(=CH_2)-CHPh- repeating units. The overall activation energy of the ring-opening polymerization was estimated to be 67.6 kJ-mol^-1. The catalysis is also effective for the ring-opening polymerization of 2-aryl-1-methylenecyclopropanes bearing substituents such as OMe, F, and Cl at the phenyl ring. End group analyses of the polymer as well as a ^13C-labeled experiment revealed a unique mechanism of the polymerization. The mechanistic study has elucidated the polymer growth which involves the new C-C bond formation between the =CH2 carbon of the monomer and benzylic carbon of the allyl Pd growng end and selective C-C bond activation of the cyclopropane ring. In Chapter 3, the author has described the ring-opening copolymerization of 2-aryl-1-methylenecyclopropanes with carbon monoxide catalyzed by Pd complexes having N-ligands. Pd complexes promoted copolymerization of 2-phenyl-1-methylenecyclopropane with carbon monoxide to afford a new polyketone. ^13C {^1H} NMR and IR studies of the produced copolymer showed the presence of α,β-unsaturated ketone group in every structural unit. Molecular weight of the polyketone attains Mn = 19,000 (Mw/Mn = 1.44) when cationic Pd-bpy complex with BARE counter anion is used as catalyst of the polymerization. The produced copolymers contain the isomeric structural units A and B, approximately in 60:40. The catalysis is also effective for the ring-opening polymerization of 2-aryl-1-methylenecyclopropanes bearing substituents such as Me and F at the phenyl ring. A plausible mechanism of the polymerization involves 1,2-insertion of the methylenecyclopropane into the Pd-acyl bond to produce a, β-cyclopropylidene alkyl palladium intermediate, which undergoes rapid β-alkyl elimination leading to Pd-alkyl complex. In Chapter 4, the author has demonstrated that Pd-complex-catalyzed copolymerization of 2-phenyl-1-methylenecyclopropane with methyl methacrylate (MMA). Although both MMA and 2-phenyl-1-methylenecyclopropane were consumed upon treatment with a Pd complex, ^13C {^1H} NMR spectrum of the obtained polymer showed only the signals assignable to both homopolymer. However, GPC and DSC analyses strongly suggest that the produced polymer is block copolymer of both monomers. Control experiments indicate that the polymerization of MMA proceed via radical mechanism, whereas 2-phenyl-1-methylenecyclopropane via allyl Pd growing species. Neutral Pd complexes such as PdCl(Me)(bpy) and [PdCl(n^3-C_3H_4R)]_2 (R = H, Ph) catalyze the homopolymerization MMA in the presence of a small amount of 2,2-diphenyl-1-methylenecyclopropane. As summarized above, this thesis has dealt with the ring-opening homo- and copolymerization of 2-aryl-1-methylenecyclopropanes catalyzed by Pd complexes. The systematic investigation on the polymerization behavior gave much information not only on the polymerization of strained cyclic olefins but also on synthetic polymer chemistry and the organometallic chemistry. Because the present system is tolerant of various substituents on the monomer, various macromolecular designs will be realized without difficulties. Furthermore, the resulting polymers have exo-methylene group on every repeating unit, which can be used for further functionalization of the polymer. The author hopes that the study described in this thesis will be applied and matured in the future.

On the Control of the Hydration of Calcium Aluuminate Compounds

유광석 Graduate School of Science and Engineering, Yamagu 2002 해외박사

この論文ではセメント鐘物としてカルシウム-アルミネ-ト系の化合物を中心に撮 い.未水和セメント粒子の表面に生成する初期水和物履が.セメント鐘物自身の反應性.添加物による反應環境によってどのよぅな性質の固體が生成するか.について檢討した. 第1章では.緖論としてまずセメントの成分について述べ.セメントの水和反應の過程を論じた.特に水和初期の水和反應の過程や未水和セメント粒子の表面に水和物の層が生成した後の水和反應の過程を重点に記述した.これと共に,實際,セメン鑛物としてポルトうンドセメントの8-9割を占おめいているカルシウムシリケ-トやカルシウムァルミネ-ト系の水和反應を上の觀點から論じた.最後に今まで報告されている添加劑による水和反應の遲延.あるいは促進メカニズムについて論じた. 第2章では.合咸溫度や冷却速度を變えること.また.不純物を添加することによって水和反應性の異なるカルシウム-アルミネ-ト系化合物を合成し.その初期水和反應を檢討したoセメントの水和反應性による初期水和物の生咸過程を觀察し.また.粒子の表面に生成した初期水和物の履による未水和セメントの水和反應への影響について檢討したoその結果.高い水和反應性によって.初期に蓚酸化力ルシウムアルミニウムケルがセメントの表面に生成し.このゲル層が次の段階の水和反應に大きな影響を與えることが分かった. 第3章では.緖論で記述した添加劑.特に遲延劑によるカルシウム-ァルミネ-ト系の水和反應性について檢討したo遲延劑としはホウ酸を用いた.ホウ酸の添加によるカルシウム-ァルミネ-ト系化合物の初期水和反應特性や初期水和物の惟質を評價し.初期水和物層による未水和セメントの水和反應速度への影響にクいて檢討した.その結果.ホウ酸の添加によって水和溶液は弱酸性に變わり.その溶液から高アルミニウム水和物ゲルが未水和粒子表面に桁出したo析出した高アルミニウム水和物ゲルは水和反應速度に大きな影響を與えることが分かったo 第4章では.水和したセメントの表面に生咸する初期水和物層の影響の他の側として,フェライト相の水和反應に及ぼすシリを-トイオンの影響にっいて檢討したoここでもセメントの表面で形咸された初期水和物層とフェライトの水和反應性の關係について檢討したoその結果.溶液からシリケ-トイオンがフェライトの表面に吸着され.シリカゲル履を作リ.アェライト相の水和反應を低下させることががかっなo 第5章では.これまで檢討した水和反應に影響を與えた初期水和物の履を物理的,化學的に評價した.これと共に實驗で予想された水和反應に及ぼす化學的な影響を分子 軌道法の計算を用いて評價した.そ·の結果.シ11ケ-トイオンは.カルシウムァルミネ-トでの添加やフエうイト相の表面での吸着によって水和反應性を低下きせることが分かったo 第6章では1-5章とで論じた內容をまよめたo There are many factors affecting the hydration rate of cement compounds, such as chemical and/or physical properties of cement compound itself, additives, curing temperature and water/cement ratio. The hydration rate is closely related with the chemical composition and atomic structures of cement compound. The morphology of particle size and surface area is also very important factor on the hydration. These factors belong to cement compound itself as internal factors. The hydration rate is also controlled with addition of admixture, such as gypsum, slag and fly ash etc, and of chemical additives, such as retarder and accelerator etc. Adding with the factors above mentioned, mixing condition of paste, curing condition and environmental affect the hydration rate of cement. The early hydration products are formed on the surface of cement particles or precipitated in the interspaces of cement particles. After the formation of the early hydration products, the hydration proceeds with the transportation of many species of ions and water molecules through the hydrates layer, whose the structure and properties, i.e., crystallization, pore structure, porosity and thickness, affect the further hydration. In this paper, these initial hydrates layers have been examined in the various solutions with the various cement compounds. In chapter 1, the cement compound was introduced, and the hydration process of cement was discussed. Since calcium silicate, calcium aluminate and ferrite usually occupy about 90 mass% of Portland cement, the research of their hydration process is also necessary to understand the hydration of cements. Finally, the mechanism of retardation or acceleration with additives was also discussed. In chapter 2, the formation mechanism of early hydrates was examined on the hydration of calcium aluminate compounds with different condition, i.e., crystalline and impurity, and the influence of the initially formed hydrates on the further hydration was also investigated. From this investigation, it was found that the high hydraulic reactivity at early stage of hydration leaded the formation of gelatinous hydrates layer on the surface of unhydrated particles. The formation of them caused the decrease of further hydration. In chapter 3, the hydration of various calcium aluminate compounds was examined under the pH-controlled solution by boric acid, and the retard mechanism was also discussed on the basis of the hydrates layer formed on the surface of unhydrated particles. Form this investigation, it was found that the precipitated aluminum gel which has a low solubility in weak acid solution, has a role as an impermeable layer, when the pH of solution is controlled to the weak acid. In chapter 4, the adsorbed hydrates layer, which was derived from the admixtures, was also investigated, From this research, it was suggested that the retardation or stop of hydration of C4AF was due to the adsorbed silicate ions from the sodium silicate solution. In chapter 5, the above-mentioned early hydrates layers, which affect the hydration rate, were summarized and evaluated with the discrete variation Xα method. The hydrates layers were divided into the group with physical effects and the group with chemical effects. Physical effects mean that the thickness and high density of hydrates layer interrupt the transportation of ions and molecules, and the chemical effects mean that the adsorption or addition of ions affect the bonding strength of cement compounds, and these bonding strength contributes to hinder the further hydration. From this research, it was found that the adsorbed and added silicate ions caused the low hydraulic activity of the hydration of C4AF and of calcium aluminate glass, respectively. In chapter 6, the above researches are summarized.

BREAKTHROUGH TECHNOLOGY FORPRODUCING BIODEGRADABLE POLYESTERS (PLA AND PBS) FROM KITCHEN REFUSE

문희천 Graduate School of Life Science and Systems Engine 2005 해외박사

음식물 쓰레기는 쉽게 부패하고 악취 및 병원균의 유발 등의 이유로 환경 오염의 주범으로 인식되어져 왔다. 하지만, 음식물 쓰레기는 미생물의 성장을 위한 풍부한 탄수화물 및 영양물질을 함유하고 있어 고 부가가치의 생산물로의 자원화가 가능하다. 이에 새로운 recycling system으로서 음식물쓰레기로부터 생 분해성 플라스틱(PLA 및 PBS) 생산 프로세스를 제안하였으며 이 두 프로세스의 개발 및 향상을 위한 단위 공정에 대해 자세히 연구하였다 첫째, PLA 프로세스에서 음식물쓰레기의 수집, 운반 및 보관 중에 자연 환경에서 우세한 젖산균들에 의한 오염으로 젖산의 두 광학 이성체(L- 및 D- 젖산)의 생성과 제어가 불가피하며 젖산 생성과정에서 고 순도 L-젖산 생성균을 이용하더라도 이들 두 이성체의 오염에 의해 PLA의 물리·화학적 물성에 큰 영향을 미친다. 음식물쓰레기 당화액의 젖산 발효 전 오염된 두 이성체의 젖산 제거를 위해 다양한 pH 조건에서 음식물쓰레기 당화 배지와 각종 탄소원을 함유한 배지를 이용하여 Propionibacteria shermanii의 젖산과 글루코스에 대한 기질 선호성, 특성 성장율(μ)과 각 기질 소비(rS)율 및 pH 조절에 의한 글루코스 보존 방법을 실험하였다. 모든 pH 조건에서 젖산에 대한 P. shermanii의 선호적 기질 특성을 확인 할 수 있었으며 젖산과 글루코스를 함유한 합성 복합 배지와 실제 음식물쓰레기 당화 배지에서 젖산에 의해 pH 6.5에서는 P. shermanii의 성장 촉진 현상을 반대로 pH 5.0에서는 성장 저해 현상이 관찰되었다. 음식물쓰레기 배지 속에 오염된 젖산의 선택적 제거와 글루코스의 보존 실험에서, pH 변화를 통해 젖산 소멸 후 약 30시간 동안 1 g/L의 아주 낮은 기질 소모율을 얻을 수 있었다. 또한 본 실험을 통해 음식물쓰레기 당화 배지는 효모 추출물과 폴리 펩톤과 같은 고 영양 성분을 함유한 배지들(LGM 및 LM)의 P. shermanii의 특성 성장율 및 기질 소모율과 비교하였을 때 미생물 성장을 위한 우수한 배지로 판명되었다. 둘째, 음식물쓰레기로부터 생 분해성 플라스틱, PBS 생산을 위해, 음식물쓰레기 숙신산 발효 농축액으로부터 antisolvent에 의한 숙신산 염 분리 정제법을 연구하였다. 음식물쓰레기 발효 농축액과 모델 숙신산 나트륨 용액을 이용해 Antisolvent의 탐색 및 첨가량에 따른 회수율 실험을 수행하였으며 발효 농축액으로부터 회수된 숙신산 나트륨의 2회 정제 과정을 통해 숙신산 나트륨의 순도 및 불순물에 대해 평가하였다. 위 두 용액 모두에서 메탄올보다 에탄올에서 높은 회수율과 안정적인 숙신산 나트륨의 침전을 형성함을 확인하였다. 에탄올을 antisolvent로 이용하여 모든 발효 농축액으로부터 1.5 EtOH/H2O 중량 비에서 95% 이상의 숙신산 나트륨의 회수율을 얻었다. 또한 에탄올에 의한 염 침전법은 발효 부산물 유기산 염으로부터 숙신산 나트륨만을 선택적으로 분리할 수 있음이 확인되었다. 회수된 분말의 2회 정제 후의 숙신산 염 순도는 96 wt%의 고 순도를 나타내었다. 그러므로 위의 두 프로세스는 현재 한국의 음식물 쓰레기의 처리 및 그것의 유용 자원화로의 획기적인 대안이 될 수 있다고 판단된다. As two prospective breakthrough technologies for developing the recycling system of kitchen refuse to biodegradable polyesters, polylactic acid (PLA) and poly(butylene succinate) (PBS), a propionic acid fermentation as a pre-fermentation for pure L_lactic acid production from kitchen refuse and a salting-out precipitation by antisolvent for sodium succinate recovery and purification from kitchen-refuse succinic acid fermentation broth, respectively, were studied. To utilize kitchen refuse as a renewable substrate for PLA production, it is essential to eliminate the L- and D-lactate naturally contaminated during its collection, transportation and storage, while preserving the glucose in it for pure L_lactic acid fermentation. The property of preferential substrate utilization by Propionibacteria shermanii on both lactate and glucose was investigated in detail by using kitchen refuse medium. The specific growth rate (μ) and the substrate consumption rate (γs) of P. shermanii on kitchen refuse medium (KRM) were compared at each pH 5.0, 5.5, 6.0 and 6.5 with artificial kitchen refuse medium (AKRM), lactate medium (LM) and lactate-glucose medium (LGM) which respectively contains glucose, lactate, and a mixture of these substrates. Lactate naturally contaminated in KRM was assimilated prior to glucose by P. shermanii at each pH. In KRM and LGM, enhancement and reduction of cell growth by lactate were observed at pH 6.5 and 5.0, respectively, when compared with that in AKRM. As a result, a glucose consumption rate in KRM was more than twice at pH 6.5, but was significantly lower than that in AKRM at pH 5.0, respectively. Glucose could be preserved by a low glucose consumption rate when pH was changed from 6.5 to 5.0 after lactate exhaustion in KRM. Preferential substrate utilization of P. shermanii on lactate than glucose and a pH change from 6.5 to 5.0 after lactate consumption was confirmed as a capable method for producing high pure L_lactic acid production from kitchen refuse. A salting-out precipitation of sodium succinate was investigated by adding various predetermined amount of methanol or ethanol as an antisolvent to model solutions containing 5-25 wt% of sodium succinate and to the sodium succinate solutions (KRFBs) which are concentrated from kitchen-refuse fermentation broth. Each KRFB contains various concentration of sodium succinate and impurities, sodium salts of by-product organic acids, sugar, and protein. In case of KRFBs, the powder recovered was refined by sequential purifications with 1.5 and 2.0 mass ratio of ethanol/water (EtOH/H₂O), respectively. Sodium succinate purity and impurities in the powder derived from each step are evaluated. Ethanol as an antisolvent shows higher and more stable succinate recovery rate than methanol in both model solution and KRFBs. Over 95 % of succinate recovery rate was obtained from each KRFB at more than 1.5 EtOH/H₂O mass ratios. A protein, a major impurity after a recovery step, was dramatically removed by the first purification. Sodium salts of by-product organic acids almost remained in EtOH/H₂O solution and were not detected in the powder after purification steps. More than 96 wt% of sodium succinate purities were achieved from individual KRFB by salting-out precipitation using antisolvent, ethanol. These results could be promising technologies to produce precursor of biodegradable plastic such as PLA and PBS from kitchen refuse as novel kitchen-refuse recycling system.