Application And Research Of Highly Dispersed Metal Nanoparticle System In Li-CO₂ Batteries

Li-CO2 batteries could skillfully combine the reduction of “greenhouse effect”with energy storage systems.Li-CO2 batteries not only reduce fossil fuel consumption,but also restrain the climate effects of CO2 emission.Additionally,Li–CO2 batteries are potential power sources for scientific exploration and future immigration to Mars,since the air there contains 95% of CO2.However,Li-CO2 batteries still suffer from unsatisfactory electrochemical performances.Part of the factors that cause this problem are the Li2CO3 self-decomposition during the charging process and the stability problems caused by the high charging voltage.By designing the new cathode material of Li-CO2 battery,the discharge product Li2CO3 is decomposed and reacted with carbon with excellent electrocatalytic activity,reducing the charging voltage and improving the cycle performance,so as to achieve high capacity,high energy density,and economical energy storage.system.In this paper,copper or ruthenium metal nanoparticles highly dispersed on graphene or nitrogen-doped graphene,which are used as the cathode material of Li-CO2 batteries to achieve low overvoltage,excellent cycle performance and high rate capability.1.In this study,a gel-like film synthesis mechanism method is presented for the preparation of a composite of Cu nanoparticles that are highly dispersed on N-doped graphene,which acts as an efficient cathode for Li-CO2 batteries.Additionally,the cathode can achieve a low overpotential of 0.77 V and has excellent cyclability(50cycles).It is speculated that superoxide radicals generated from the self-decomposition of Li2CO3 unavoidably corrode electrodes during the charge process.Nevertheless,the surface of the Cu nanoparticles forms a 3-5 nm thick Cu O film that protects and stabilizes the cathode during later cycles.2.A composite of ruthenium–copper nanoparticles highly co-dispersed on graphene as efficient air cathodes for Li–CO2 batteries is designed.The Li-CO2 batteries with this cathode exhibit ultra-low overpotential and can be operated for 100 cycles with a fixed capacity of 1000 m Ah g-1 at 200 and 400 m A g-1.The synergistic effect between Ru and Cu not only regulates the growth of discharge products,but also promotes CO2 reduction and evolution reactions by changing the electron cloud density of the surface between Ru and Cu.3.Prepared ruthenium nanoparticles highly dispersed in nitrogen-doped graphene composite material as the cathode material of Li–CO2 batteries.Due to the material changes brought about by N doping,the cycle stability of the battery has also been improved.The Li-CO2 batteries with this cathode can be operated for 50 cycles with a fixed capacity of 1000 m Ah g-1 at 200 and 400 m A g-1.The formation and decomposition of discharge products verified the good reversibility and electrocatalytic activity.