The pore size distribution is often an important parameter for transport processes in porous media.Cryoporometry experiments can provide such data in the meso and macropore size up to 1 mm providing the sample tempera...The pore size distribution is often an important parameter for transport processes in porous media.Cryoporometry experiments can provide such data in the meso and macropore size up to 1 mm providing the sample temperature is finely controlled.We use a Peltier based system inserted directly into the NMR probe to control the temperature within 0.05℃and impose temperature ramps down to 0.002℃/min,necessary to characterize the largest pore sizes.The pore size information in the macropore range cannot be obtained from gas adsorption techniques while mercury injection is questionable for the material considered here.For porous materials made of paramagnetic minerals such as lithium-iron phosphate(LiFePO_(4),LFP)or nickel-manganese-cobalt oxides(NMC)and saturated with octamethylcyclotetrasiloxane(OMCTS),the T_(2)relaxation times are very short such as protons from the liquid and frozen phases cannot be separated.Hence the usual cryoporometry experiment cannot be performed.Instead,we propose to use the T_(1)contrast to separate these phases.The method is studied in detail along with some temperature effects linked with the T_(1)variation of the bulk frozen OMCTS.We show an example on two cathode materials part of industrial battery product.展开更多
Solid-state lithium metal batteries(SSLMBs)are considered an auspicious technology to develop high energy density and safe energy storage devices.The double layer polymer electrolyte(DLPE)is a rational approach for en...Solid-state lithium metal batteries(SSLMBs)are considered an auspicious technology to develop high energy density and safe energy storage devices.The double layer polymer electrolyte(DLPE)is a rational approach for engineering high-performance SSLMBs addressing electrolyte requirements with specifically designed polymers at the positive electrode and as separator.In this work,SSLMBs were assembled with poly(propylene carbonate)(PPC),offering stability toward oxidation at the positive electrode,and a gel polymer electrolyte with polyethyleneglycol dimethylether(PEGDME)as separator,offering high ionic conductivity at low temperature and sufficient interfacial stability with Li metal.The electrochemical properties and performance of cells with LiFePO_(4) and Li[Ni_(0.6)Mn_(0.2)Co_(0.2)]O_(2) positive electrodes are thoroughly investigated as function of the operating temperature by using a host of characterization techniques.High-voltage cells with an areal capacity of 0.7 mAh·cm^(−2)cycled at 40℃ exhibit a higher capacity retention than the cells cycled at 70℃.To understand such differences,a three-electrode setup is applied to discriminate anodic processes from cathodic as function of the temperature.We elucidate the ageing and interfacial evolution for DLPE cells with gel polymer electrolytes paving the way for building performance solid state batteries.展开更多
文摘The pore size distribution is often an important parameter for transport processes in porous media.Cryoporometry experiments can provide such data in the meso and macropore size up to 1 mm providing the sample temperature is finely controlled.We use a Peltier based system inserted directly into the NMR probe to control the temperature within 0.05℃and impose temperature ramps down to 0.002℃/min,necessary to characterize the largest pore sizes.The pore size information in the macropore range cannot be obtained from gas adsorption techniques while mercury injection is questionable for the material considered here.For porous materials made of paramagnetic minerals such as lithium-iron phosphate(LiFePO_(4),LFP)or nickel-manganese-cobalt oxides(NMC)and saturated with octamethylcyclotetrasiloxane(OMCTS),the T_(2)relaxation times are very short such as protons from the liquid and frozen phases cannot be separated.Hence the usual cryoporometry experiment cannot be performed.Instead,we propose to use the T_(1)contrast to separate these phases.The method is studied in detail along with some temperature effects linked with the T_(1)variation of the bulk frozen OMCTS.We show an example on two cathode materials part of industrial battery product.
文摘Solid-state lithium metal batteries(SSLMBs)are considered an auspicious technology to develop high energy density and safe energy storage devices.The double layer polymer electrolyte(DLPE)is a rational approach for engineering high-performance SSLMBs addressing electrolyte requirements with specifically designed polymers at the positive electrode and as separator.In this work,SSLMBs were assembled with poly(propylene carbonate)(PPC),offering stability toward oxidation at the positive electrode,and a gel polymer electrolyte with polyethyleneglycol dimethylether(PEGDME)as separator,offering high ionic conductivity at low temperature and sufficient interfacial stability with Li metal.The electrochemical properties and performance of cells with LiFePO_(4) and Li[Ni_(0.6)Mn_(0.2)Co_(0.2)]O_(2) positive electrodes are thoroughly investigated as function of the operating temperature by using a host of characterization techniques.High-voltage cells with an areal capacity of 0.7 mAh·cm^(−2)cycled at 40℃ exhibit a higher capacity retention than the cells cycled at 70℃.To understand such differences,a three-electrode setup is applied to discriminate anodic processes from cathodic as function of the temperature.We elucidate the ageing and interfacial evolution for DLPE cells with gel polymer electrolytes paving the way for building performance solid state batteries.
