LiCoO2 gradient coated LiNi0.96Co0.04O2 material and iso-structure LiNi0.8Co0.2O2 material (the same molar ratio 8/2 of Ni/Co in the two materials) as cathode for lithium-ion batteries were synthesized with a co-preci...LiCoO2 gradient coated LiNi0.96Co0.04O2 material and iso-structure LiNi0.8Co0.2O2 material (the same molar ratio 8/2 of Ni/Co in the two materials) as cathode for lithium-ion batteries were synthesized with a co-precipitation method. Microstructure of iso-structure LiNi0.8Co0.2O2 were about the same as that of LiNiO2, and the structure of the coated material was much more similar to that of LiCoO2 based on the X-ray diffraction patterns. The cycling voltammetry and galvanostatic cycle tests show that the properties of the coated material were improved significantly. The first specific charge and discharge capacity for the coated material was 249.20 mAh·g-1 and 207.90 mAh·g-1 respectively, and the specific discharge capacity for the 100th cycle was still 186.02 mAh·g-1 with an irreversible loss of only 21.1 mAh·g-1. This showed that the new material had a good lithium intercalation-deintrercalation performance. Meanwhile, the mechanism of the sintering reaction was proposed. During the sintering reaction of the precursor with LiOH, the Li+-ion permeated into the body of precursors because the shape of the precursor particles was not changed basically based on scanning electronic microscopy. So, the layer microstructure of the precursor is important for the layer microstructure of lithium nickel cobalt oxides electrode material.展开更多
This paper presents a new method of surface modification on LaNi5 hydr ogen storage alloy. The hydrogen alloy was treated in the acid CuSO4 solution co ntaining HF. The effect of HF on surface state of alloy was studi...This paper presents a new method of surface modification on LaNi5 hydr ogen storage alloy. The hydrogen alloy was treated in the acid CuSO4 solution co ntaining HF. The effect of HF on surface state of alloy was studied and the elec trochemical properties of modified alloy were investigated. Electrochemical impe dance spectra (EIS) was also applied to analyze the resistance property of alloy electrode after modification. SEM and XRD results showed that HF had corrosive effect on hydrogen alloy, which help copper grain to precipitate on alloy surfac e. EIS analysis showed that modified alloy had lower contact resistance and elec trochemical polarization, which resulted in a higher conductivity and electroche mical activation. Electrochemical testing showed modified alloy had better activ ation behavior and excellent large current discharge ability. Thus it could well satisfy the requirement of the application as power sources on electric vehicle s.展开更多
The electrochemical surface area (ESA) of the half-membrane electrode assembly (HMEA) and dimethyl-ether (DME) electrooxidation on the HMEA were examined by cyclic voltammetry (CV). The ESAs of the electrode before an...The electrochemical surface area (ESA) of the half-membrane electrode assembly (HMEA) and dimethyl-ether (DME) electrooxidation on the HMEA were examined by cyclic voltammetry (CV). The ESAs of the electrode before and after DME electrooxidation were calculated from the integrated charge during the adsorption (and/or desorption) of atomic hydrogen minus the charge for the double layer charging in 0.5 mol·L-1 H2SO4. The increase in ESA was observed, and this was attributed to the change of catalyst layer structure, leading to a more effective contact between catalysts and the electrolyte Nafion.展开更多
文摘为研究铝在海水中的腐蚀过程,采用电化学阻抗谱、浸泡试验、扫描电子显微镜研究工业纯铝在模拟海水中的腐蚀行为.结果表明:铝在模拟海水中发生点蚀的区域为富含Fe的晶间化合物处,点蚀半径随时间的增加而扩大.铝在模拟海水中的溶解曲线分为4个区间:活性溶解区、过渡区、过钝化区、钝化区.铝在模拟海水中,极化电位为过钝化区时,转移电阻R t随着电位的升高而变小,铝发生严重的点蚀;而极化电位为钝化区时,铝的转移电阻R t随着电位的升高基本不变,铝的溶解行为受到抑制.工业纯铝在模拟海水中发生点蚀的电位区间是-0.45～-0.65 V,钝化电位区间为-0.75～-0.85 V.
文摘LiCoO2 gradient coated LiNi0.96Co0.04O2 material and iso-structure LiNi0.8Co0.2O2 material (the same molar ratio 8/2 of Ni/Co in the two materials) as cathode for lithium-ion batteries were synthesized with a co-precipitation method. Microstructure of iso-structure LiNi0.8Co0.2O2 were about the same as that of LiNiO2, and the structure of the coated material was much more similar to that of LiCoO2 based on the X-ray diffraction patterns. The cycling voltammetry and galvanostatic cycle tests show that the properties of the coated material were improved significantly. The first specific charge and discharge capacity for the coated material was 249.20 mAh·g-1 and 207.90 mAh·g-1 respectively, and the specific discharge capacity for the 100th cycle was still 186.02 mAh·g-1 with an irreversible loss of only 21.1 mAh·g-1. This showed that the new material had a good lithium intercalation-deintrercalation performance. Meanwhile, the mechanism of the sintering reaction was proposed. During the sintering reaction of the precursor with LiOH, the Li+-ion permeated into the body of precursors because the shape of the precursor particles was not changed basically based on scanning electronic microscopy. So, the layer microstructure of the precursor is important for the layer microstructure of lithium nickel cobalt oxides electrode material.
文摘This paper presents a new method of surface modification on LaNi5 hydr ogen storage alloy. The hydrogen alloy was treated in the acid CuSO4 solution co ntaining HF. The effect of HF on surface state of alloy was studied and the elec trochemical properties of modified alloy were investigated. Electrochemical impe dance spectra (EIS) was also applied to analyze the resistance property of alloy electrode after modification. SEM and XRD results showed that HF had corrosive effect on hydrogen alloy, which help copper grain to precipitate on alloy surfac e. EIS analysis showed that modified alloy had lower contact resistance and elec trochemical polarization, which resulted in a higher conductivity and electroche mical activation. Electrochemical testing showed modified alloy had better activ ation behavior and excellent large current discharge ability. Thus it could well satisfy the requirement of the application as power sources on electric vehicle s.
文摘The electrochemical surface area (ESA) of the half-membrane electrode assembly (HMEA) and dimethyl-ether (DME) electrooxidation on the HMEA were examined by cyclic voltammetry (CV). The ESAs of the electrode before and after DME electrooxidation were calculated from the integrated charge during the adsorption (and/or desorption) of atomic hydrogen minus the charge for the double layer charging in 0.5 mol·L-1 H2SO4. The increase in ESA was observed, and this was attributed to the change of catalyst layer structure, leading to a more effective contact between catalysts and the electrolyte Nafion.
