Abstract: The invention disclosed is an alkali metal-ion secondary cell having a carbonaceous anode and an electrolyte, comprising an alkali metal salt dissolved in an organic electrolyte solvent. Intercalation and de-intercalation during repeated charge/discharge cycle of the secondary cell using a conventional electrolyte solvent causes continual exposure of bare surfaces of the carbonaceous material to the electrolyte, resulting in continual consumption of electrolyte in the formation of new passivation films on the bared or partially covered surfaces, adversely affecting the performance and capacity of the cell. An improvement on the conventional electrolyte involves the addition of fluorinated organic solvent to the conventional electrolyte and results in a more stable passivation film, much less consumption of electrolyte and better performance and cell capacity.

Abstract: The invention disclosed relates to a new method of forming spinel-related .lambda.-Li.sub.2-x Mn.sub.2 O.sub.4, wherein 0.ltoreq.x.ltoreq.2, solely by electrochemical means with air-stable orthorhombic LiMnO.sub.2 as the starting material. This spinel-related material is hydroscopic, metastable and is typically made by chemical means, followed by electrochemical conversion of spinel-type LiMn.sub.2 O.sub.4. Also disclosed are new secondary lithium ion electrochemical cells employing as initial active cathode material a compound of formula LiMnO.sub.2, having a specific orthorhombic crystal structure.

Abstract: The invention disclosed relates to a new method of forming spinel-related .lambda.-Li.sub.2-x Mn.sub.2 O.sub.4, wherein 0.ltoreq.x.ltoreq.2, solely by electrochemical means with air-stable orthorhombic LiMnO.sub.2 as the starting material. This spinel-related material is hydroscopic, metastable and is typically made by chemical means, followed by electrochemical conversion of spinel-type LiMn.sub.2 O.sub.4. Also disclosed are new secondary lithium ion electrochemical cells employing as initial active cathode material a compound of formula LiMnO.sub.2, having a specific orthorhombic crystal structure.

Abstract: A conventional electrolyte for a secondary cell having a carbonaceous anode is comprised of an alkali metal salt dissolved in an organic electrolyte solvent. Intercalation and de-intercalation during repeated discharge/charge cycles of the secondary cell using a conventional electrolyte solvent causes continual exposure of bare surfaces of the carbonaceous material to the electrolyte, resulting in continual consumption of electrolyte in the formation of new passivation films on the bared or partially covered surfaces, adversely affecting the performance and capacity of the cell. In accordance with the present invention, the organic electrolyte solvent comprises chloroethylene carbonate, propylene carbonate and ethylene carbonate. The chloroethylene carbonate is capable of forming a very stable passivation film on the anode. The performance and capacity of the secondary cell is improved substantially by the addition of the halogenated organic solvent.

Abstract: A conventional electrolyte for a secondary cell having a carbonaceous anode is comprised of an alkali metal salt dissolved in an organic electrolyte solvent. Intercalation and de-intercalation during repeated discharge/charge cycles of the secondary cell using a conventional electrolyte solvent causes continual exposure of bare surfaces of the carbonaceous material to the electrolyte, resulting in continual consumption of electrolyte in the formation of new passivation films on the bared or partially covered surfaces, adversely affecting the performance and capacity of the cell. In accordance with the present invention, at least a portion of the organic electrolyte solvent is replaced with a chloroethylene carbonate solvent capable of forming a very stable passivation film. The performance and capacity of the secondary cell is improved substantially by the addition of the halogenated organic solvent to propylene carbonate.

Abstract: The invention disclosed relates to a new method of forming spinel-related .lambda.-Li.sub.2-x Mn.sub.2 O.sub.4, wherein 0.ltoreq.x.ltoreq.2, solely by electrochemical means with air-stable orthorhombic LiMnO.sub.2 as the starting material. This spinel-related material is hydroscopic, metastable and is typically made by chemical means, followed by electrochemical conversion of spinel-type LiMn.sub.2 O.sub.4. Also disclosed are new secondary lithium ion electrochemical cells employing as initial active cathode material a compound of formula LiMnO.sub.2, having a specific orthorhombic crystal structure.

Abstract: The invention disclosed relates to a novel compound of molecular formula Li.sub.2 Cr.sub.x Mn.sub.2-x O.sub.4, wherein 0<X<2. This compound may be used as the active cathode material in secondary lithium ion cells. Secondary lithium ion cells including such cathodes are also described.