Fluorinated Polymer, Method of Making, and Use in Electrochemical Cell



Low specific capacity and low charge/discharge rate of current cathodic materials are the bottle-neck for the next generation electrochemical energy storage devices, particularly for “on-demand applications.” Current batteries rely on transition metal salts (e.g. LiMO2, LiMPO4) and mixed metal oxide lithium salts as cathodic materials. The heavy nature of these transition metal elements limits their capacity. Fluorinated carbon has been the main component of primary lithium batteries since the 1970s. The high capacity cathodic material suffers from low conductivity and slow electron transfer kinetics resulting in a low discharging rate. Furthermore, preparation of fluorinated carbon materials results in large variation and the challenge of product quality control as well as a significant safety threat associated with production of the materials. Though recent approaches to modification of carbon nanotube-based fluorinated carbon materials have improved the rate capacity, the natural low loading capacity of these nanomaterials and requirement of addition of conducting materials (e.g. carbon black) and mechanical binding materials limits its practical application where large loading capacity is required.


To solve this low conductivity and low discharge rate problem for fluorinated carbon-based cathodic materials, researchers at USD have designed a new type of fluorinated carbon material that contains an electronically-conducting polymer backbone, an aromatic-based electron-transfer catalyst unit, and an energy storage unit (perfluoroalkyl chains) yet still maintains the composition of fluorinated carbon to keep the high specific capacity. This is attained through the use of a thiophene unit as the electronically-conducting monomer to form the backbone by electrochemical polymerization or oxidative chemical polymerization; an electron poor nitrogen-containing dibenzophenazine core as the electron transfer (ET) catalytic center; and long perfluoroalkyl chains as the energy storage units that are directly connected to the ET catalytic center through covalent bonds to facilitate rapid ET reaction. The electron-poor aromatic core possesses higher reduction potential compared to electron rich ones, providing higher voltage when assembled into a full battery cell.


Patent Information:
For Information, Contact:
Rozzy Finn
Technology Transfer Officer
University of South Dakota
Haoran Sun