Electrochemical Synthesis of Composite Films of Manganese Dioxide and Polypyrrole and Their Properties as an Active Material in Lithium Secondary Batteries

Abstract

Composite films of polypyrrole and ~-MnO2 or lithiated MnO2 (Li-MnQ) particles have been synthesized for use as cathode-active materials of rechargeable lithium batteries. The composite films were prepared by electrolysis of pyrrole dissolved in propylene carbonate solution in the presence~ of suspended MnO2 particles. The maximum amount of the incorporation of MnO2 was 50.2 and 40.6 weight percent for ~-MnO2 and Li-MnO2, respectively. It was found that both polypyrrole and the incorporated MnO2 worked as the active material with one potential plateau in the charge-discharge test conducted in a mixed solution of propylene carbonate and dimethoxyethane in which LiC104 was dissolved. Furthermore, it was shown that polypyrrole worked as a conducting network for the incorporated MnO2. Though the utilization of the incorporated MnO2 was not high (~-MnO2 and Li-MnO2 gave 0.23 and 0.57, respectively), the composite films prepared under optimal electrolysis conditions gave the specific energy density on volume basis of more than 150% of that obtained for a fully-utilized MnQ-free polypyrrole. Elemental analysis of the composite films revealed that electrolyte anions alone were involved in the redox reaction of polypyrrole of the composite films and Li § ions in the redox reaction of the incorporated MnO2.

Materiais para cátodos de baterias secundárias de lítio

“…Uma vez que o polímero é eletroquimicamente ativo, o compósito constituído de 15% de PPy sobre a massa total do cátodo apresentou propriedades eletroquímicas superiores em relação ao filme dióxido de manganês contendo carbono negro na mesma estequiometria. Contudo, apesar do processo redox sob o PPy/MnO 2 envolver a participação de Li + na compensação de cargas do óxido, verificou-se a participação dos íons ClO 4 -nas etapas de oxidação/redução do material orgânico 184,185 , como mostra a Figura 11. Acredita-se que o aumento na quantidade de ânions no filme de PPy/MnO 2 em relação ao PPy se deve aos íons Cl -adsorvidos sobre as partículas de MnO 2 durante a preparação do material.…”

“…Quando o composto inorgânico não atua como contra-ânion para [184] o material orgânico, uma alternativa para evitar a participação de ânions é a produção de materiais híbridos constituídos de polímeros condutores auto-dopados. Um compósito formado à base da polianilina sulfonada SPAN e MnO 2 (ramsdellita) ainda apresentou uma capacidade de descarga maior do que cátodos de SPAN e uma melhor ciclabilidade em relação ao óxido puro 197 .…”

Electrochemical characterization of a polypyrrole/Co0.2CrOx composite as a cathode material for lithium ion batteries

“…The redox reaction of the polypyrrole and the consequent lithium intercalation serves as the source of the capacity during cycling. Kuwabata et al [11][12][13][14] have doped polypyrrole into MnO 2 , LiMn 2 O 4 , V 2 O 5 , etc. and found that the doping improved the performance of these cathode materials.…”

Characteristics of aqueous polycarbazole batteries

“…[1][2] Copolymerization, incorporation of electroactive anions as fixed charge compensators, use of polymer composites with inorganic oxide materials and molten salt electrolytes with aluminium as counter electrode are some of the recent strategies applied to improve the performance of polymer batteries. [3][4][5][6][7][8] Another significant development is the recent work involving the use of solid polymer electrolytes such as polyethylene oxide and polyacrylonitrile as battery electrolytes. 9 -11 Their light weight and flexibility will enable the realization of ultrathin batteries with very high energy densities.…”