| Optimizing the energy structure and improving the efficiency of clean energy utilization,such as solar energy,wind energy,tidal energy,geothermal energy,etc.,are important means to implement the "dual carbon" plan strategy.However,the generation of renewable clean energy is greatly affected by factors such as geography,time,and temperature.Developing advanced energy storage technologies is the key to improving the utilization efficiency of clean energy.Based on the advantages of environmentally friendly,easy synthesis,good processing properties,and controllable structure,ion batteries based on polymer electrode materials are expected to be used in the next generation of high-performance lithium-ion batteries.This paper proposes to construct a all-polymer battery using the high redox potential nitroxide radical(TEMPO)polymer as the positive electrode material and the low potential azobenzene(Azo)functionalized polymer(PAzo)as the negative electrode material.The polymer chain structure design and the redox side group structure regulation will be used to optimize the electrode material performance,and to reveal the relationship between polymer structure and electrochemical and energy storage properties.The research results are expected to broaden the practical application of all-organic polymer batteries and the specific research contents are as follows:(1)Redox mediator enhanced TEMPO polymer redox kinetics:In theory,TEMPO can undergo a two-electron reversible redox reaction(3.7,2.5 V vs.Li+/Li),but the slow electron exchange in the second electron process(2.5V vs.Li+/Li)leads to extremely low energy storage efficiency based on the second electron process.In the first work,we introduced a redox mediator,anthraquinone(AQ),into the 2,2,6,6tetramethylpiperidine-1-oxyl(TEMPO)polymer,effectively improving the redox kinetics of the second electron process of TEMPO and promoting the two-electron storage performance of TEMPO polymers.The results show that the copolymer P(TMA-co-AQ)/Li with the introduction of redox mediator exhibits a stable twoelectron charge-discharge plateau(3.6 V and 2.2 V vs.Li+/Li),with a discharge capacity of approximately 85 mAh g-1 based on TEMPO·/-(the second electron plateau),which is 30%higher than that of the original PTMA.The initial capacity of the electrode is 174 mAh g-1,and the capacity loss per cycle is only 0.18%.(2)Relationship between Side Chain Structure and Electrochemical Performance of Azobenzene Polymers:Developing novel negative electrode polymers and lowering their negative potential through chemical structure control are major challenges for improving the performance of all-polymer batteries.Azobenzene structures possess reversible redox properties and exhibit simple and efficient chemical structure modifications.In the second work,we synthesized polymer negative electrode materials containing azobenzene redox-active centers,and elucidated the relationship between structure and electrochemical properties by controlling the electron-donating and electron-withdrawing groups of the monomer active centers.The results showed that introducing electron-donating groups such as methyl and methoxy can effectively reduce the redox potential of azobenzene polymers,from-1.75 V(H-AZO-H)to-1.87 V(H-AZO-Me)and-1.93 V(H-AZO-OMe),respectively.Finally,among the three azobenzene polymer negative electrode materials tested in half-cell tests,methyl azobenzene polymer demonstrated good cycling stability and rate performance,with an initial discharge specific capacity of 177 mAh g-1 at a current density of 0.5 C.The assembled TEMPO/AZO polymer all-organic battery exhibits a discharge voltage of approximately 2.0 V and a discharge specific capacity of 40 mAh g-1,thereby further expanding the range of all-organic polymer batteries. |
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