Gaseous electrolyte additive BF3 for high-power Li/CFx primary batteries

Abstract

Lithium/graphite fluoride (Li/CFx) batteries have attracted great attention because of the highest energy density among all commercially available lithium primary batteries. However, the inferior electrochemical performances at high discharge current densities impede their applications in high-power devices. Herein, we have found a novel and low-cost gaseous electrolyte additive BF3 that can remarkably improve the rate capability of the Li/CFx batteries. The CFx (x=1.15) cathode in the carbonate electrolyte with 0.01M BF3 additive can deliver a maximum power density of 23040 W kg−1 with a high gravimetric energy density of 722.8 Wh kg−1. By contrast, the CFx cathodes in the electrolyte without additive can barely provide capacity at discharge rates above 5C. Such significant enhancement can be attributed to the ability of the BF3 additive to dissolve the insulating discharge product LiF without passivating the cathode surface and impeding the intercalation of lithium ions. This work provides a way that enables Li/CFx batteries to have an ultrahigh power density comparable to that of supercapacitors while maintaining high energy densities.