Herein, three kinds of Li2CO3 and two kinds of MgCO3·3H2O crystals are easily synthesized in a homogeneouslike organic phase. The morphology and size of synthesized crystals are controllable and adjustable in the...Herein, three kinds of Li2CO3 and two kinds of MgCO3·3H2O crystals are easily synthesized in a homogeneouslike organic phase. The morphology and size of synthesized crystals are controllable and adjustable in the single organic phase, with the morphology of Li2CO3 ranging from micro-flaky, flower to nanobranch, MgCO3·3H2O rangi ng from nanosphere to nanorod. Compared with coupled reacti on and solve nt extraction process, of which the crystallization process occurred in the interface of two phase, our proposed method made it possible that the crystallization process occurred in the single organic phase, which resulted in better crystal morphology. Moreover, the formation mechanism of different crystal morphologies is discussed, the results showed that the crystals in micron size and nano size are involved in two crystallization mechanism, the micron particles in the form of flake and flower-like is a typical radial growth, which means that the growth occurs by diffusion around a nucleus as starting point, while the reaction model for small particles should be similar to a water-in-oil structure. As the reaction carried out, the crystal should be restricted in a constrained organic structure.展开更多
Lithium carbonate （Li2CO3） is very common in various types of lithium （Li） batteries. As an insulating by-product of the oxygen reduction reaction on the cathode of a Li-air battery, it cannot be decomposed below ...Lithium carbonate （Li2CO3） is very common in various types of lithium （Li） batteries. As an insulating by-product of the oxygen reduction reaction on the cathode of a Li-air battery, it cannot be decomposed below 4.75 V （vs. Li＋/Li） during recharge and leads to a large polarization, low coulombic efficiency, and low energy conversion efficiency of the battery. On the other hand, more than 10% of the Li ions from the cathode material are consumed during chemical formation of a Li-ion battery, resulting in low coulombic efficiency and/or energy density. Consequently, lithium compensation becomes essential to realize Li-ion batteries with a higher energy density and longer cycle life. Therefore, reducing the oxidation potential of Li2CO3 is significantly important. To address these issues, we show that the addition of nanoscaled LiCoO2 can effectively lower this potential to 4.25 V. On the basis of physical characterization and electrochemical evaluation, we propose the oxidization mechanism of Li2CO3. These findings will help to decrease the polarization of Li-air batteries and provide an effective strategy for efficient Li compensation for Li-ion batteries, which can significantly improve their energy density and increase their energy conversion efficiency and cycle life.展开更多
The effects of temperature on the convecsion of Li2 CO3 Co LiOH in a Ca（OH）2 suspension were investigated. Li2CO3 microplates were used as the Li source. The results showed that Li2CO3 was converted to LiOH via in s...The effects of temperature on the convecsion of Li2 CO3 Co LiOH in a Ca（OH）2 suspension were investigated. Li2CO3 microplates were used as the Li source. The results showed that Li2CO3 was converted to LiOH via in situ ion-exchange and dissolution-precipitation routes. The formation of mixed CaxLiz-2xCO3 inter- mediate species confirmed that at 25℃ need/e-like CaCO3 was formed heterogeneously on the Li2CO3 surface via in situ ion-exchange. At 60-100℃, isolated CaCO3 agglomerates were formed homogeneously via dissolution-precipitation. Temperature increases accelerated the dissolution and conversion of Li2 CO3 to LiOH, producing solutions with high [CO32-1][Ca^2＋] ratios; this favored homogeneous precipitation of isolated CaCO3 agglomerates,展开更多
基金Supported by the National Natural Science Foundation of China(U1607118)
文摘Herein, three kinds of Li2CO3 and two kinds of MgCO3·3H2O crystals are easily synthesized in a homogeneouslike organic phase. The morphology and size of synthesized crystals are controllable and adjustable in the single organic phase, with the morphology of Li2CO3 ranging from micro-flaky, flower to nanobranch, MgCO3·3H2O rangi ng from nanosphere to nanorod. Compared with coupled reacti on and solve nt extraction process, of which the crystallization process occurred in the interface of two phase, our proposed method made it possible that the crystallization process occurred in the single organic phase, which resulted in better crystal morphology. Moreover, the formation mechanism of different crystal morphologies is discussed, the results showed that the crystals in micron size and nano size are involved in two crystallization mechanism, the micron particles in the form of flake and flower-like is a typical radial growth, which means that the growth occurs by diffusion around a nucleus as starting point, while the reaction model for small particles should be similar to a water-in-oil structure. As the reaction carried out, the crystal should be restricted in a constrained organic structure.
基金This work was supported by the National Basic Research Program of China （No. 2015CB251100） and the National Natural Science Foundation of China （No. 51372268）.
文摘Lithium carbonate （Li2CO3） is very common in various types of lithium （Li） batteries. As an insulating by-product of the oxygen reduction reaction on the cathode of a Li-air battery, it cannot be decomposed below 4.75 V （vs. Li＋/Li） during recharge and leads to a large polarization, low coulombic efficiency, and low energy conversion efficiency of the battery. On the other hand, more than 10% of the Li ions from the cathode material are consumed during chemical formation of a Li-ion battery, resulting in low coulombic efficiency and/or energy density. Consequently, lithium compensation becomes essential to realize Li-ion batteries with a higher energy density and longer cycle life. Therefore, reducing the oxidation potential of Li2CO3 is significantly important. To address these issues, we show that the addition of nanoscaled LiCoO2 can effectively lower this potential to 4.25 V. On the basis of physical characterization and electrochemical evaluation, we propose the oxidization mechanism of Li2CO3. These findings will help to decrease the polarization of Li-air batteries and provide an effective strategy for efficient Li compensation for Li-ion batteries, which can significantly improve their energy density and increase their energy conversion efficiency and cycle life.
文摘The effects of temperature on the convecsion of Li2 CO3 Co LiOH in a Ca（OH）2 suspension were investigated. Li2CO3 microplates were used as the Li source. The results showed that Li2CO3 was converted to LiOH via in situ ion-exchange and dissolution-precipitation routes. The formation of mixed CaxLiz-2xCO3 inter- mediate species confirmed that at 25℃ need/e-like CaCO3 was formed heterogeneously on the Li2CO3 surface via in situ ion-exchange. At 60-100℃, isolated CaCO3 agglomerates were formed homogeneously via dissolution-precipitation. Temperature increases accelerated the dissolution and conversion of Li2 CO3 to LiOH, producing solutions with high [CO32-1][Ca^2＋] ratios; this favored homogeneous precipitation of isolated CaCO3 agglomerates,
基金Project(2008BAB35B04) supported by the National Key Technologies R&D Program of ChinaProject(2010QZZD003) supported by Central South University Advanced Research Program,China
