Tsinghua University School of Materials made another breakthrough in high-rate lithium-ion battery materials
Recently, the research group of Professor Tang Zilong of the School of Materials Science and Technology of Tsinghua University published the research results titled "High-rate vanadate lithium ion battery cathode material with glass-ceramic phase" in the journal Advanced Energy Materials. Based on the research of high-rate lithium titanate hydrate electrode materials, this study further solved the problems of low volume energy density, low coulombic efficiency and rapid capacity decay of nano-electrode materials.
In lithium-ion batteries, nano-electrode materials have the advantages of short-range ion diffusion distance and fast reaction kinetics, but the high specific surface area makes them prone to particle agglomeration and serious side reactions with organic electrolytes during electrode preparation and circulation Although the micron-level electrode material can effectively reduce the contact area with the electrolyte and increase the compaction density, its ion diffusion capacity is usually insufficient to meet the rapid insertion and extraction of ions in a short time. Therefore, designing a micron-level dense nanocrystalline material with both fast ion channels and low specific surface area can effectively solve the above problems.
Unlike traditional bottom-up methods for synthesizing nano-micro materials (such as spray granulation, co-precipitation self-assembly, etc.), this study uses a top-down micro-nano material synthesis strategy-first synthesis of micro-scale The vanadate precursor is then introduced into the glass-ceramic phase intermediate state through the low-temperature phase transition process, and at the same time the crystal grains are refined, thereby obtaining micron-level dense nanocrystalline electrode materials. This vanadate electrode material with a glass-ceramic phase not only has a rich grain boundary / phase interface to ensure the rapid transmission of lithium ions, but also has a small specific surface area to reduce the surface vice between the electrolyte reaction. Based on the above advantages, the vanadate cathode material exhibits excellent large-rate, high-capacity, and long-cycle electrochemical performance. This synthesis strategy is also universal for other transition metal oxide electrode materials whose precursors are hydrates, and also provides new ideas for the design of micro-nano structures in energy storage materials.
The corresponding authors of the paper are Professor Tang Zilong of the School of Materials, Tsinghua University, Dr. Shitong Wang and Dr. Dong Yanhao of the Massachusetts Institute of Technology, and the first author is Li Yutong, a 2016 doctoral student at the School of Materials, Tsinghua University. The research was supported by the National Natural Science Foundation of China.
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