The Electrochemical Performance Of Transition Metal Compound Electrode Materials

In today’s world,fossil energy is the main source of global energy depletion.With the rapid progress of human society,fossil energy has been exploited in large quantities,resulting in the decreasing reserves of fossil energy and its adverse impact on the environment.Since fossil energy is not renewable,it is urgent to change the existing energy structure and explore renewable energy sources.The development of conventional renewable energy sources,such as wind,solar,and tidal energy,is limited by the nature of intermittent work and uneven geographical distribution.For these reasons,the development of devices for safe and efficient energy conversion and storage systems is in great demand.Secondary batteries,as a type of chemical battery,use the reversibility of chemical reactions to convert and store energy between chemical and electrical energy.As the major secondary battery energy storage device,lithium ion batteries have been used on a large scale since the 1990s and have the advantages of longer service life,less pollution,lighter and easier to carry.Nevertheless,the distribution of lithium ore resources in the earth’s crust is very limited,the high price and toxicity of cobalt oxide,lead to the high cost of lithium battery process,and the poor safety stability of traditional lithium battery electrolyte in air also limit the application and development of lithium-ion batteries.This paper mainly researches and discusses the electrochemical performance of the transition metal compound electrode materials of secondary batteries,and conducts an in-depth discussion on the electrochemical performance and energy storage mechanism of the electrode materials.The specific research results are as follows.（1）Aluminum ion battery cathode materials with FeSe₂/MoS₂ heterostructure nanoflowers were successfully synthesized experimentally.FeSe₂/MoS₂ with large specific surface area for electrochemical reactions to provide more reaction sites and plenty of ion diffusion channels,and a lot of storage space for Al Cl₄^-storage.FeSe₂/MoS₂ has a reversible capacity of 222 m A h g^-1 at 0.5 A g^-1 and 116 m A h g^-1 at1.0 A g^-1,with no significant capacity decay even after 140 cycles.The DFT theoretical calculations and experimental results confirm that the improvement of the FeSe₂/MoS₂heterojunction by the built-in electric field can significantly increase the ionic conductivity,accelerate the interfacial charge transfer,and lead to a significant increase in the reversible capacity of the cell.（2）Ti₃C₂T_x MXene（Mn-Ti₃C₂T_x）materials with surface functional groups complexed with Mn⁴⁺were prepared as cathode materials for aqueous zinc ion batteries.The high redox activity of manganese was utilized to load Mn⁴⁺onto the surface end of Ti₃C₂T_x MXene with a reversible capacity of 228 m A h g^-1 at 0.3 A g^-1,which is much higher than that of Ti₃C₂T_x without material modification.Mn-Ti₃C₂T_x has a discharge voltage plateau as high as 1.4 V.Even at a high current density of 5 A g^-1,the Mn-Ti₃C₂T_x electrode can maintain an ultra-high capacity of 81%after 1000 stable cycles.（3）Waster-paper-synthesized conductive paper（CP）and active material MnO₂together is developed to obtain a new type of anode without any binder for lithium ion batteries.By this way,we can obtain low density anode with active material in CP,instead of the commonly-used heavy metal current collector.The multi walled carbon nanotube（MWCNT）was added in serves as a component of CP and the conductive agent for active material.It delivered an initial specific capacity of 1629.9 m A h g^-1 at a current density of 100 m A g^-1 and maintained about 70%even after 100 cycles.What’s more,it shows reversible capacity of about 260 m A h g^-1 at high current density of 1000m A h g^-1.