The University of Science and Technology of China has developed a route for preparing graphite anode from a polymer-binder-free slurry, which can universally construct a new particle size-porosity dual gradient structure in graphite anode, which greatly improves lithium ion The fast charging performance of the battery. The related results were recently published in the international journal Science Advances.
The fast charging capability of electric vehicles is limited by the high concentration polarization effect and low equilibrium potential of the graphite anode in lithium-ion batteries. At high charging rates, lithium metal deposition and dendrite growth are easily induced, resulting in battery performance degradation. and security issues arise. Strategies such as porous graphite particles, interface modification of graphite anodes, and orientation of graphite particles have been used to improve the fast charging performance of graphite anodes. However, the design strategies of these graphite anodes often improve the fast charging performance at the expense of the energy density of the fabricated batteries. How to overcome the contradiction between the high energy density and fast charging performance of Li-ion batteries remains a challenging problem. The research team first used a particle-scale theoretical model and an iterative design method to simulate the structure of the graphite anode electrode. At the same time, the dual distribution of particle size and electrode porosity is optimized. The simulation results show that compared with the traditional random electrode and single gradient electrode, the lithium ion concentration distribution in the electrolyte inside the electrode is smoother, and the performance of the dual gradient distribution electrode is smoother. It exhibits smaller concentration polarization and higher utilization of active materials, showing excellent fast charging performance. The researchers further developed a low-viscosity polymer-free binder slurry self-assembly technology to prepare copper nanowires and copper particle-coated graphite low-viscosity ethanol slurry, using the difference in the sedimentation velocity of graphite particles of different sizes in the slurry. , a dual-gradient structure optimized by simulation calculation was successfully constructed in the graphite anode, and the lithium-ion full battery prepared based on the graphite anode exhibited the same excellent fast charging performance as the experimental model.
This study proposes to introduce a gradient heterogeneous distribution structure design of particle size and porosity inside the graphite anode without sacrificing the energy density of the lithium-ion battery, and realize the improvement of the fast charging performance of the graphite anode.