Block copolymer electrolytes for lithium batteries

Abstract

Many of the problems in current rechargeable lithium batteries arise due to the presence of a volatile and flammable liquid electrolyte, and the inherent instability of the electrode-electrolyte interface. We demonstrate that replacing the electrolyte with a hard solid electrolyte holds promise for improving both specific energy and safety of lithium batteries. The electrolyte, obtained by self-assembly of block copolymer/salt mixtures, comprises soft conducting channels laced with lithium salts embedded in a hard insulating matrix. The width of the channels can be readily controlled in the 5-50 nm range. These electrolytes exhibit many surprising properties. In contrast to both current liquid and solid electrolytes, the ionic conductivity of the electrolyte increased with increasing molecular weight, thus enabling optimization of both its electrical and mechanical properties. The talk concludes with a description of the effect of lithium salts on block copolymer self-assembly.