?-Graphyne adjusted diffusion-capacitance behavior of lithium titanate for boosting high-rate and wide-temperature lithium storage

Pursuing high power density and wide-temperature environmental adaptability is vital to broadening the utilization of lithium titanate (LTO) anodes in start-stop batteries of electric vehicles. Here, we introduce ?-graphyne, an emerging carbon allotrope composed of sp- and sp(2)-hybridized carbon, to encapsulate LTO particles via a onepot ball milling. ?-Graphyne with a two-dimensional p-conjugated structure contains abundant electron-rich acetylene linkages in favor of fast electron conduction and, more importantly, it is a promising Li-ion host delivering a certain capacitance within the typical potential window of LTO. The optimum LTO/?-graphyne composite shows outstanding rate capability (83 % retention of 10C compared to 0.5C), long-term cycling stability (91 % retention over 1000 cycles at 2C), and high low-temperature retentivity (102 mAh g(- 1) at -20 ? after 500 cycles at 1C, 63 % utilization of that at 25 ?). The impressive performance arises from adjusted diffusion-capacitance Li storage behavior with significantly reduced plateau-potential polarization and enhanced interfacial ionic migration capability. This work highlights an electrochemical active, highly conductive alkyne carbon candidate endowing full-climate applications of LTO anodes.

Automated summary

This study introduces ?-graphyne as an encapsulation material for lithium titanium oxide (LTO) particles, aiming to improve their power density and environmental adaptability in start-stop batteries of electric vehicles. The optimized LTO/?-graphyne composite exhibits outstanding rate capability, long-term cycling stability, and high low-temperature retention. These impressive performances are attributed to adjusted diffusion-capacitance Li storage behavior with reduced plateau-potential polarization and enhanced interfacial ionic migration capability.