High elastic modulus polymer electrolytes suitable for preventing thermal runaway in lithium batteries

Abstract

A polymer that combines high ionic conductivity with the structural properties required for Li electrode stability is useful as a solid phase electrolyte for high energy density, high cycle life batteries that do not suffer from failures due to side reactions and dendrite growth on the Li electrodes, and other potential applications. The polymer electrolyte includes a linear block copolymer having a conductive linear polymer block with a molecular weight of at least 5000 Daltons, a structural linear polymer block with an elastic modulus in excess of 1×107 Pa and an ionic conductivity of at least 1×10−5 Scm−1. The electrolyte is made under dry conditions to achieve the noted characteristics. In another aspect, the electrolyte exhibits a conductivity drop when the temperature of electrolyte increases over a threshold temperature, thereby providing a shutoff mechanism for preventing thermal runaway in lithium battery cells.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation-in-part of the international application PCT / US2007 / 008435 filed on Apr. 3, 2007, titled HIGH ELASTIC MODULUS POLYMER ELECTROLYTES; which claims priority to U.S. Provisional Patent Application No. 60 / 744,243 filed Apr. 4, 2006, titled HIGH ELASTIC MODULUS POLYMER ELECTROLYTES; and to U.S. Provisional Patent Application No. 60 / 820,331 filed Jul. 25, 2006, titled SYNTHESIS OF DRY POLYMER ELECTROLYTES. The disclosures of applications listed above are incorporated herein by reference in their entirety and for all purposes.STATEMENT OF GOVERNMENTAL SUPPORT[0002]This invention was made with government support under Contract DE-AC02-05CH11231 awarded by the United States Department of Energy to The Regents of the University of California for the management and operation of the Lawrence Berkeley National Laboratory. The government has certain rights in this invention.FIELD OF THE INVENTION[0003]The invention rel...

AI Technical Summary

Benefits of technology

[0014]In a further aspect, the invention relates to battery cells comprising a Li anode, a cathode and linear block copolymer electrolyte in accordance with the invention disposed between the anode and cathode. The cell can be cycled without detrimental dendrite growth on the anode. In one embodiment, the battery cell includes a linear block copolymer electrolyte which exhibits a drop in conductivity once the temperature exceeds a threshold temperature. In some embodiments, the threshold temperature is in a range from 90° C. to 150° C., and the conductivity drop is at least 2-fold, or at least 5-fold, and, preferably, at least 10-fold. Such polymer electrolytes can be used to prevent thermal runaway in a lithium metal battery.

Problems solved by technology

This conductivity drop is due to precipitation of the lithium salt in the block copolymer, which, unexpectedly occurs with temperature increase.

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