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Li[Li0.2Ni 0.16Mn 0.56Co 0.08]O 2 Nanoparticle/Carbon Composite Using Polydopamine Binding Agent for Enhanced Electrochemical Performance.

Lim SB, Park YJ - Nanoscale Res Lett (2015)

Bottom Line: The Super P particles were dispersed on the surface of Li[Li0.2Ni0.16Mn0.56Co0.08]O2 powders.The composite samples that were heat-treated in a N2 atmosphere showed increased capacity and enhanced rate capability, which was caused by the improved electronic conductivity owing to the presence of carbon.However, the composite samples that were heat-treated in air did not present these carbon-related effects clearly.

View Article: PubMed Central - PubMed

Affiliation: Department of Advanced Materials Engineering, Kyonggi University, San 94-6, Yiui-dong, Yeongtong-gu, Suwon, Gyeonggi-do, 443-760, Republic of Korea, yjparketri@yahoo.co.kr.

ABSTRACT
Li[Li0.2Ni0.16Mn0.56Co0.08]O2 nanoparticles were composited with carbon (Super P) in order to achieve an enhanced rate capability. A polydopamine pre-coating layer was introduced to facilitate the adhesion between Super P and pristine nanoparticles. The Super P particles were dispersed on the surface of Li[Li0.2Ni0.16Mn0.56Co0.08]O2 powders. The composite samples that were heat-treated in a N2 atmosphere showed increased capacity and enhanced rate capability, which was caused by the improved electronic conductivity owing to the presence of carbon. However, the composite samples that were heat-treated in air did not present these carbon-related effects clearly. The capacity changes observed during the first several cycles may be due to the oxygen deficiency of the structure caused by the heat-treatment process.

No MeSH data available.


Related in: MedlinePlus

Schematic diagram of the procedure used for the synthesis of the Li[Li0.2Ni0.16Mn0.56Co0.08]O2/Super P composite using a polydopamine pre-coating layer
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Fig1: Schematic diagram of the procedure used for the synthesis of the Li[Li0.2Ni0.16Mn0.56Co0.08]O2/Super P composite using a polydopamine pre-coating layer

Mentions: To prepare the polydopamine pre-coating layer, each of the two pristine powders was mixed with a dopamine (Aldrich) solution containing Tris buffer (10 mM; pH 8.5; Aldrich) and methanol (Aldrich, 99.9 %) as co-solvents (CH3OH:Tris buffer = 1:1 vol%). Through this mixing process, the polymerization process occurred, and a polydopamine layer formed on the surface of pristine powders. The mixture was mechanically stirred at room temperature until all particles were suspended in the solution. Then, the mixture was centrifuged, washed several times with ethanol and distilled water, and dried at 90 °C for 24 h [12, 21, 30–34]. The polydopamine pre-coated powder was added to the carbon (Super P) solution and stirred at 70 °C until all of the solvent evaporated. The carbon content was adjusted to 3 wt% cathode powder. The sample was then dried at 90 °C for 24 h and heat-treated at 350 °C for 3 h in either a N2 atmosphere or an air atmosphere. The polydopamine pre-coating layer on the powder surface was removed during the annealing process. Figure 1 shows the scheme used for the synthesis of the Li[Li0.2Ni0.16Mn0.56Co0.08]O2 nanoparticles/Super P composite using the polydopamine pre-coating layer. The surface morphologies of the samples were analyzed using field emission scanning electron microscopy (FE-SEM, Nova Nano 200). For electrochemical testing, a slurry was prepared by mixing the cathode composite powder with carbon black (Super P) and polyvinylidene fluoride (PVDF) at a weight ratio of 80:10:10 for the cathode composite powder, Super P, and PVDF, respectively. A coin-type cell (2032) configuration composed of a cathode, a Li-metal anode, a separator, and an electrolyte was used. The electrolyte used was a 50:50 vol.% mixture of LiPF6 (1 M) and ethylene carbonate/dimethyl carbonate (EC/DMC). Impedance measurements were carried out using an electrochemical workstation (AMETEK, VersaSTAT 3) by applying an AC voltage with an amplitude of 5 mV over a frequency range of 0.1 to 100 kHz.Fig. 1


Li[Li0.2Ni 0.16Mn 0.56Co 0.08]O 2 Nanoparticle/Carbon Composite Using Polydopamine Binding Agent for Enhanced Electrochemical Performance.

Lim SB, Park YJ - Nanoscale Res Lett (2015)

Schematic diagram of the procedure used for the synthesis of the Li[Li0.2Ni0.16Mn0.56Co0.08]O2/Super P composite using a polydopamine pre-coating layer
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4481243&req=5

Fig1: Schematic diagram of the procedure used for the synthesis of the Li[Li0.2Ni0.16Mn0.56Co0.08]O2/Super P composite using a polydopamine pre-coating layer
Mentions: To prepare the polydopamine pre-coating layer, each of the two pristine powders was mixed with a dopamine (Aldrich) solution containing Tris buffer (10 mM; pH 8.5; Aldrich) and methanol (Aldrich, 99.9 %) as co-solvents (CH3OH:Tris buffer = 1:1 vol%). Through this mixing process, the polymerization process occurred, and a polydopamine layer formed on the surface of pristine powders. The mixture was mechanically stirred at room temperature until all particles were suspended in the solution. Then, the mixture was centrifuged, washed several times with ethanol and distilled water, and dried at 90 °C for 24 h [12, 21, 30–34]. The polydopamine pre-coated powder was added to the carbon (Super P) solution and stirred at 70 °C until all of the solvent evaporated. The carbon content was adjusted to 3 wt% cathode powder. The sample was then dried at 90 °C for 24 h and heat-treated at 350 °C for 3 h in either a N2 atmosphere or an air atmosphere. The polydopamine pre-coating layer on the powder surface was removed during the annealing process. Figure 1 shows the scheme used for the synthesis of the Li[Li0.2Ni0.16Mn0.56Co0.08]O2 nanoparticles/Super P composite using the polydopamine pre-coating layer. The surface morphologies of the samples were analyzed using field emission scanning electron microscopy (FE-SEM, Nova Nano 200). For electrochemical testing, a slurry was prepared by mixing the cathode composite powder with carbon black (Super P) and polyvinylidene fluoride (PVDF) at a weight ratio of 80:10:10 for the cathode composite powder, Super P, and PVDF, respectively. A coin-type cell (2032) configuration composed of a cathode, a Li-metal anode, a separator, and an electrolyte was used. The electrolyte used was a 50:50 vol.% mixture of LiPF6 (1 M) and ethylene carbonate/dimethyl carbonate (EC/DMC). Impedance measurements were carried out using an electrochemical workstation (AMETEK, VersaSTAT 3) by applying an AC voltage with an amplitude of 5 mV over a frequency range of 0.1 to 100 kHz.Fig. 1

Bottom Line: The Super P particles were dispersed on the surface of Li[Li0.2Ni0.16Mn0.56Co0.08]O2 powders.The composite samples that were heat-treated in a N2 atmosphere showed increased capacity and enhanced rate capability, which was caused by the improved electronic conductivity owing to the presence of carbon.However, the composite samples that were heat-treated in air did not present these carbon-related effects clearly.

View Article: PubMed Central - PubMed

Affiliation: Department of Advanced Materials Engineering, Kyonggi University, San 94-6, Yiui-dong, Yeongtong-gu, Suwon, Gyeonggi-do, 443-760, Republic of Korea, yjparketri@yahoo.co.kr.

ABSTRACT
Li[Li0.2Ni0.16Mn0.56Co0.08]O2 nanoparticles were composited with carbon (Super P) in order to achieve an enhanced rate capability. A polydopamine pre-coating layer was introduced to facilitate the adhesion between Super P and pristine nanoparticles. The Super P particles were dispersed on the surface of Li[Li0.2Ni0.16Mn0.56Co0.08]O2 powders. The composite samples that were heat-treated in a N2 atmosphere showed increased capacity and enhanced rate capability, which was caused by the improved electronic conductivity owing to the presence of carbon. However, the composite samples that were heat-treated in air did not present these carbon-related effects clearly. The capacity changes observed during the first several cycles may be due to the oxygen deficiency of the structure caused by the heat-treatment process.

No MeSH data available.


Related in: MedlinePlus