Dip-spin coating of reticulated vitreous carbon with composite materials to act as an electrode for 3D microstructured lithium ion batteries

摘要

This paper describes a new and economic route for the formation of three dimensional (3D) microstructured battery electrodes using our "in house" developed dip-spin coating technique for depositing layers of active material onto reticulated vitreous carbon (RVC) substrates. These coatings are optimized composite materials containing carbon black and polymer binder to facilitate good electronic and ionic conductivities through the electrode. The application process begins by immersing the substrate in an ink followed by rapid spinning to provide a uniform coating with a well controlled mass loading. The performance of the electrodes was investigated in lithium ion cells as a function of the composition of the inks used and the number of dip-spin coating cycles. Optimization of the ink composition, dip and spin parameters has improved the electrochemical performances of the electrodes to give state of the art footprint area specific capacities (>1000 μA h cm~(-2)) and high rate capabilities (nearly 50% degree of discharge at 25 C) in lithium half cells. This represents the first stage in the development of a full 3D microbattery system. Initial results have also shown the versatility of this approach in depositing other electrode materials by forming uniform layers of both TiO_2 and LiMn_2O_4.