Composite electrolytes for lithium rechargeable batteries

The paper reviews and presents attributes of emerging polymer-ceramic composite electrolytes for lithium rechargeable batteries. The electrochemical data of a diverse range of composite electrolytes reveal that the incorporation of a ceramic component in a polymer matrix leads to enhanced conductivity, increased lithium transport number, and improved electrode-electrolyte interfacial stability. The conductivity enhancement depends upon the weight fraction of the ceramic phase, annealing parameters, nature of polymer-ceramic system, and temperature. The ceramic additive also increases the effective glass transition temperature and thus decouples structural and electrical relaxation modes which in turn increases the lithium transport number. The ceramic additives also provide a range of free energy of reactions with lithium. A few of the ceramic materials (MgO, CaO, Si3N4) have positive free energy of reaction and they should not passivate lithium electrodes.