On February 3, the research group of Professor Tang Zilong from the School of Materials Science and Technology of Tsinghua University published in the "Advanced Energy Materials" (Advanced Energy Materials) journal titled "High-rate vanadate lithium-ion battery cathode materials with a glass-ceramic phase" ( Glass-Ceramic-Like Vanadate Cathodes for High-Rate Lithium-Ion Batteries). 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 rapid 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 ability 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-micron materials (such as spray granulation, co-precipitation self-assembly, etc.), this study uses a top-down micro-nano material synthesis strategy-first synthesis of micron-level The vanadate precursor is then introduced into the glass-ceramic phase intermediate state through the low-temperature phase transition process, and the grains are refined, thereby obtaining micron-sized dense nanocrystalline electrode materials (as shown in Figure 1). This vanadate electrode material with 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.