IT Home news on December 12, at present, electric vehicles are facing problems such as short mileage and insufficient safety, which restricts their large-scale promotion. If electric vehicles have a range comparable to that of fuel vehicles, consumers will no longer have range anxiety when driving electric vehicles, which is conducive to the large-scale promotion of electric vehicles.
According to the Ningbo Institute of Materials Technology and Engineering, among the currently known cathode materials, the discharge specific capacity of lithium-rich manganese-based cathode materials is as high as 300mAh/g, which is about twice the discharge specific capacity of cathode materials such as lithium iron phosphate and ternary materials currently commercially applied. Therefore, lithium-rich manganese-based cathode materials are considered to be ideal for a new generation of high-energy density power lithium batteries, and it is also the technical key to the energy density of power lithium batteries to exceed 400Wh/kg.
In the past ten years, Liu Zhaoping, a researcher at the Power Lithium Battery Engineering Laboratory of the Ningbo Institute of Materials Technology and Engineering of the Chinese Academy of Sciences, has long been committed to the research and development of lithium-rich manganese-based cathode materials, and has carried out research and achieved a series of research results around key scientific issues such as reducing the first irreversible capacity of lithium-rich manganese-based cathode materials, voltage attenuation and oxygen precipitation during cycling.
IT Home learned that recently, the research team has conducted in-depth research on the relationship between nickel and cobalt elements and oxygen activity in lithium-rich manganese-based cathode materials and the modification and optimization of lithium-rich manganese-based cathode materials, and has made a series of progress. First, in collaboration with researchers at the University of California, San Diego, they conducted a study on the activity of nickel-cobalt and oxygen in lithium-rich manganese-based cathode materials using large scientific devices such as the Shanghai light source and the Dongguan hash neutron source (Figure 1), which was recently published online in Materials Today.
Figure 1
At the same time, in view of the contradiction between the oxygen activity utilization and its energy efficiency of lithium-rich manganese-based cathode materials (Figure 2), the research team cooperated with researchers at Brookhaven National Laboratory in the United States to conduct in-depth research, using in situ X-ray diffraction spectroscopy and in situ X-ray absorption spectroscopy, revealing the correlation between lattice oxygen redox kinetics and transition metal migration and rearrangement rate, and found that by fine-tuning the chemical composition to moderately reduce Li content and increase Ni content, the expansion of Li2MnO3 phase domain can be effectively limited. In addition, reversible Ni mixture is induced in the chemical process of power generation, so that Ni ions block the diffusion migration path of Mn ions, thereby alleviating the phenomenon of ion migration hysteresis during the electrochemical reaction to a certain extent. This study provides a new idea for the design of lithium-rich manganese-based cathode materials with high energy efficiency and long cycle stability. The study was published in Energy Storage Materials.
Figure 2
In addition, the research team comprehensively used surface modification methods such as surface doping, gas-solid interface modification, and surface coating to achieve the construction of composite surface structure (Figure 3), and prepared a lithium-rich manganese-based cathode material with high specific capacity and long cycle stability. The research team used the lithium-rich manganese-based cathode material and the graphene composite silicon carbon anode material to design and develop a new type of battery with an energy density of 345Wh/kg (capacity 20Ah), and showed excellent cycle stability. The study was published in the Journal of Materials Chemistry A.
Figure 3