• 한국세라믹학회지
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• 제43권9호
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• pp.588-593
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• 2006

Spinel phase $LiMn_2O_4$ is of great interest as cathode materials for lithium-ion batteries. In this study, SHS (Self propagating High-temperature Synthesis) method to synthesize spinel $LiMn_2O_4$ directly from lithium nitrate, manganese oxide, manganese and sodium chloride were investigated. The influence of Li/Mn ratio, the heat-treated condition of product have been explored. The resultant $LiMn_2O_4$ synthesized under the optimum synthesis conditions shows perfect spinel structure, uniform particle size and excellent electrochemical performances.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권3호
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• pp.179-184
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• 1999

In the past ten years, $LiMn_2O_4$-based spinels have been extensively studied as positive electrode materials for lithium-ion batteries. To improve the cycle performance of spinel $LiMn_2O_4$ as the cathode of 4V class lithium secondary batteries, spinel phases $LiMn_2O_4$ were prepared at various temperatures ranging form 600-900$^{\cire}C$ in air. The results showed that charge.dischare capacity of $LiMn_2O_4$ varied at 1st temperature from $200^{\circ}C to 600^{\circ}C$ increase with increasing temperature. $LiMn_2O_4$ synthesized at 2nd temperature $750^{\circ}C$excellent charge.discharge capacity, efficiency and cyclability compared to the samplesynthesized different temperatures. The value of lst charge.discharge capacity was 121mAh/g, 118mAh/g, Also, the efficiency value was about 97%.

• Journal of Electrochemical Science and Technology
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• 제1권2호
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• pp.97-101
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• 2010

In order to apply hybrid capacitor, $Li_2Mn_3O_7$ was synthesized by combustion method using $LiNO_3$, $Li(CH_3COO){\cdot}2H_2O$ and $Mn(CH_3COO){\cdot}4H_2O$. Spinel pattern was identified the samples calcined over $400^{\circ}C$ in XRD. Intensity of $Mn_2O_3$ peak increased as the calcination temperature increased. To decide n/p ratio and to investigate electrochemical properties, charge-discharge tests of Li/$Li_2Mn_3O_7$ and Li/AC half-cell were carried out. Applying to AC/$Li_2Mn_3O_7$ hybrid capacitor, it had high discharge capacitance of 32.8 F/cc at 100 mA/g.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.595-596
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• 2005

This research which it sees adds $LiMn_2O_4$ in the activated carbon electrode the test against the effect which it follows is. Test cells, which were $LiMn_2O_4$fabricated with active mass composite consisted of (100-X)% of MSP-20 and (X)% of $LiMn_2O_4$ (X=20,40,60,80,100), exhibits the better specific capacitance than those of the cells fabricated with single active mass that is MSP-20. The enhanced properties of composite active mass could be caused by capability of $LiMn_2O_4$ powders. But the resistance was increase by proportionate in $LiMn_2O_4$ addition and when mixture ratio of the activated carbon and the $LiMn_2O_4$ being similar, to be low rather to the after where had become the maximum it came.

• 한국세라믹학회지
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• 제41권10호
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• pp.735-741
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• 2004

단순화한 연소법에 의해 합성한 $LiMn_{1.92}Co_{0.08}O_4$와 $LiNi_{0.7}Co_{0.3}O_2$의 혼합물의 전기화학적 성질을 알아보기 위하여, 30분 동안 milling하여 $LiMn_{1.92}Co_{0.08}O_4$-x wt$\%$ $LiNi_{0.7}Co_{0.3}O_2$ (x=9, 23, 33, 41, and 47) 조성의 혼합물을 제조하였다. x=9 조성의 전극이 비교적 큰 초기방전용량(109.9mAh/g at 0.1C)과 좋은 싸이클 성능을 가지고 있었다. 싸이클링에 따른 혼합물 전극의 방전용량 감소는 주로 $LiNi_{0.7}Co_{0.3}O_2$의 퇴화에 기인한다고 생각된다. $LiNi_{0.7}Co_{0.3}O_2$의 퇴화는 $LiMn_{1.92}Co_{0.08}O_4$로부터 용해된 Mn이 $LiNi_{0.7}Co_{0.3}O_2$ 입자를 둘러싸서(coating) 일어나는 것으로 판단된다.

• 한국전기전자재료학회논문지
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• 제14권4호
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• pp.316-322
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• 2001

Cathode materials $LiMn_{2-y}$$M_{y}$ $O_4$(M=Zn and Mg) were obtained by reacting the mixture of LiOH.$H_2O$, Mn $O_2$ and MgO ar ZnO at 80$0^{\circ}C$ for 36h in an air atmosphere. These materials showed an extended cycle life in lithium-anode cells working at room temperatue in a 3.0 to 4.3V potential window. Among these materials, LiM $n_{1.9}$M $g_{0.1}$ $O_4$ showed the best cycle performance in terms of the capacity and cycle life. The discharge capacities of the cathode for the Li/LiM $n_{1.9}$ $M_{0.1}$ $O_4$ cell at the 1st cycle and at the 70th cycle were about 120 and 105mAh/g, respectively. This cell capacity is retained by 88% after 70th cycle. In cyclic voltammetry measurement, all cells revealed tow oxidation peaks and reduction peaks. However, Li/$LiMn_{2-y}$$M_{y}$ $O_4$ cell substituted with Zn and Mg showed new reaction peak during reduction reaction.eaction.ion.ion.

• Korean Chemical Engineering Research
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• 제47권1호
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• pp.84-88
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• 2009

Al이 치환된 $LiMn_2O_4$ 미세 분말을 구연산과 에틸렌 글리콜이 첨가된 분무용액으로부터 분무열분해 공정에 의해 합성하였다. 구형의 형상, 다공성의 구조 및 마이크론 크기를 가지는 전구체 분말들은 $800^{\circ}C$ 이상의 후열처리 온도에서 마이크론 크기 및 균일한 형태를 가지는 $LiMn_{11/6}Al_{1/6}O_4$ 분말들로 전환되었다. 후열처리 온도가 $700^{\circ}C$ 일 때 $LiMn_{11/6}Al_{1/6}O_4$ 분말은 94 mAh/g의 낮은 초기 방전 용량을 가졌다. 후열처리 온도가 $750^{\circ}C$에서 $1,000^{\circ}C$로 증가함에 따라 $LiMn_{11/6}Al_{1/6}O_2$ 분말의 초기 방전 용량은 103 mAh/g에서 117 mAh/g로 변화하였으며, 후열처리 온도 $750^{\circ}C$에서 최대 초기 방전용량을 가졌다. 반면에 후열처리 온도 $900^{\circ}C$에서 얻어진 $LiMn_{11/6}Al_{1/6}O_2$ 분말들이 좋은 사이클 특성을 가졌다. 전류밀도 0.1 C에서 70 사이클 충방전 후에 $LiMn_{11/6}Al_{1/6}O_4$ 분말들의 방전 용량은 107 mAh/g에서 100 mAh/g으로 감소하였고 93%의 사이클 효율을 유지하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.268-268
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• 2009

Li-Mn spinel의 고온수영 특성을 향상을 위해 졸-겔법으로 $V_2O_5$를 Li-Mn spinel 표면에 코팅을 하였다. $V_2O_5$의 코팅양은 1, 3, 5wt%로 조절하여 코팅 양에 따른 특성변화를 조사하였다. XRD분석결과 $V_2O_5$가 코팅된 Li-Mn spinel을 $400^{\circ}C$에서 열처리시 $Mn(VO_3)_2$가 생성되는 것을 확인하였다. 충방전 테스트결과, 고온에서 $V_2O_5$를 코팅한 Li-Mn spinel이 우수한 수명을 나타냈다. 하지만 코팅량이 1wt%까지는 용량의 변화가 거의 없었고, 5wt% 코팅시 현격히 용량이 감소하였다.

• 한국응용과학기술학회지
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• 제20권1호
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• pp.33-43
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• 2003

$LiMn_2O_4$ catalyst for $CO_2$ decomposition was synthesized by oxidation method for 30 min at 600$^{\circ}C$ in an electric furnace under air condition using manganese(II) nitrate $(Mn(NO_3)_2{\cdot}6H_2O)$, Lithium nitrate ($LiNO_3$) and Urea $(CO(NH_2)_2)$. The synthesized catalyst was reduced by $H_2$ at various temperatures for 3 hr. The reduction degree of the reduced catalysts were measured using the TGA. And then $CO_2$ decomposition rate was measured using the reduced catalysts. Phase-transitions of the catalysts were observed after $CO_2$ decomposition reaction at an optimal decomposition temperature. As the result of X-ray powder diffraction analysis, the synthesized catalyst was confirmed that the catalyst has the spinel structure, and also confirmed that when it was reduced by $H_2$, the phase of $LiMn_2O_4$ catalyst was transformed into $Li_2MnO_3$ and $Li_{1-2{\delta}}Mn_{2-{\delta}}O_{4-3{\delta}-{\delta}'}$ of tetragonal spinel phase. After $CO_2$ decomposition reaction, it was confirmed that the peak of $LiMn_2O_4$ of spinel phase. The optimal reduction temperature of the catalyst with $H_2$ was confirmed to be 450$^{\circ}C$(maximum weight-increasing ratio 9.47%) in the case of $LiMn_2O_4$ through the TGA analysis. Decomposition rate(%) using the $LiMn_2O_4$ catalyst showed the 67%. The crystal structure of the synthesized $LiMn_2O_4$ observed with a scanning electron microscope(SEM) shows cubic form. After reduction, $LiMn_2O_4$ catalyst became condensed each other to form interface. It was confirmed that after $CO_2$ decomposition, crystal structure of $LiMn_2O_4$ catalyst showed that its particle grew up more than that of reduction. Phase-transition by reduction and $CO_2$ decomposition ; $Li_2MnO_3$ and $Li_{1-2{\delta}}Mn_{2-{\delta}}O_{4-3{\delta}-{\delta}'}$ of tetragonal spinel phase at the first time of $CO_2$ decomposition appear like the same as the above contents. Phase-transition at $2{\sim}5$ time ; $Li_2MnO_3$ and $Li_{1-2{\delta}}Mn_{2-{\delta}}O_{4-3{\delta}-{\delta}'}$ of tetragonal spinel phase by reduction and $LiMn_2O_4$ of spinel phase after $CO_2$ decomposition appear like the same as the first time case. The result of the TGA analysis by catalyst reduction ; The first time, weight of reduced catalyst increased by 9.47%, for 2${\sim}$5 times, weight of reduced catalyst increased by average 2.3% But, in any time, there is little difference in the decomposition ratio of $CO_2$. That is to say, at the first time, it showed 67% in $CO_2$ decomposition rate and after 5 times reaction of $CO_2$ decomposition, it showed 67% nearly the same as the first time.

• 전기화학회지
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• 제3권3호
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• pp.131-135
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• 2000

[ $LiMn_2O_4$ ]박막전지의 충방전 사이클에 따른 용량 감소의 원인을 파악하기 위하여, $LiMn_2O_4/1M\;LiClO_4-PC/Li$전지를 구성하여 충방전 사이클에 따른 AC impedance분석을 수행하였다. 적절한 등가회로를 이용하여 비선형 최소자승 맞춤에서 얻은 값이 Impedance측정 결과와 잘 일치하였다. 충방전에 따른 정전용량은 초기의 급격한 감소를 보인 이후 완만한 감소를 보였다. 충방전 사이클이 초기 70-100사이클까지는 저항 성분 중 양극전해질 계면의 전하 전달저항 성분이 급격히 증가하다가 이후 안정된 값을 보임으로 초기 급격한 용량변화의 원인으로 파악되었다. 전하전달 저항이 안정된 이후에는 Warburg저항이 충방전에 따라 조금씩 증가하였으며, LiMn2O4박막의 화학확산 계수가 사이클에 따라 초기 $5.15\times10^{-11}cm^2/sec$에서 800사이클이 지난 후 $6.3\times10^{-12}cm^2/sec$로 점차 감소하는 것이 관찰되어 100사이클이 후의 용량감소의 지배적 원인으로 파악하였다. Warburg저항의 증가는 Jahn-Teller변형 또는 Mn용해에 의한 것으로 추정하였다.