Multi-layered composite electrodes of high power Li4Ti5O12 and high capacity SnO2 for smart lithium ion storage

Discrete layering of high power Li4Ti5O12 and high capacity SnO2 in a through-thickness multi-layered composite electrode was achieved using a layer-by-layer spray printing approach in order to explore new capacity-power combinations for lithium ion based electrochemical energy storage. Electrochemical behavior of multi-layered electrodes was optimized as a function of the thickness of the discrete SnO2 layer, in the range 2 to 6 µm, interleaved between two layers of low volume expansion Li4Ti5O12. Three discrete layers of 2 µm SnO2 were then interleaved evenly between Li4Ti5O12 layers to produce a “layer cake” negative electrode cross-section that offered remarkable rate capability when coupled with a spray printed LiFePO4 positive electrode in a lithium ion battery arrangement. The multi-layered negative electrode was also coupled with a spray printed activated carbon positive electrode in a lithium ion capacitor configuration, providing significant improvements in energy density. The double-sided fabrication of the multi-layer electrode over a 20 × 20 cm2 current collector area suggested a possible hybrid electrochemical device that combines attributes of high capacity lithium ion batteries and high power lithium ion capacitors.