Impact of PSBpin Content on the Electrochemical Properties of PTMA-PSBpin Copolymer Cathodes

The class of radical polymers is one of the most appealing electrode materials in organic radical batteries (ORBs). Herein, we report a series of copolymers poly(2,2,6,6-tetramethylpiperidinyloxyl-4-yl methacrylate)-poly(4-pinacolatoborylstyrene) (PTMA-PSBpin-n, n = 1, 2, and 3) and explore their electrochemical properties as cathodes for ORBs. At 50 wt % active material content, the PTMA-PSBpin electrodes are found to bear great capacity, long-term cycle life, and impressive rate performance. In addition, compared to the other two electrodes, the PTMA-PSBpin-3 electrode possesses the lowest voltage separation (Delta V), which owes much to the introduction of a higher content of the PSBpin unit that enhances the conductivity (in the range of 3.447 x 10(-3) to 5.219 x 10(-3) S cm(-1) within the pressure range of 2.0-20 MPa) of the material and resultantly abases the ohmic resistance. Accordingly, the oxidation/reduction mechanism during the discharge/charge process is revealed by electron paramagnetic resonance (EPR) spectra. This study will shed light on the development of advanced ORB cathodes with low cost and high performance.