Co–B Nanoflakes as Multifunctional Bridges in ZnCo_2O_4 Micro-/Nanospheres for Superior Lithium Storage with Boosted Kinetics and Stability

摘要

Transition metal oxides hold great promise as high-energy anodes in next-generation lithium-ion batteries. However, owing to the inherent limitations of low electronic/ionic conductivities and dramatic volume change during charge/discharge, it is still challenging to fabricate practically viable compacted and thick TMO anodes with satisfactory electrochemical performance. Herein, with mesoporous cobalt-boride nanoflakes serving as multifunctional bridges in ZnCo2O4 micro-anospheres, a compacted ZnCo2O4/Co-B hybrid structure is constructed. Co-B nanoflakes not only bridge ZnCo2O4 nanoparticles and function as anchors for ZnCo2O4 micro-anospheres to suppress the severe volume fluctuation, they also work as effective electron conduction bridges to promote fast electron transportation. More importantly, they serve as Li+ transfer bridges to provide significantly boosted Li+ diffusivity, evidenced from both experimental kinetics analysis and density functional theory calculations. The mesopores within Co-B nanoflakes help overcome the large Li+ diffusion barriers across 2D interfaces. As a result, the ZnCo2O4/Co-B electrode delivers high gravimetric/volumetric/areal capacities of 995 mAh g(-1)/1450 mAh cm(-3)/5.10 mAh cm(-2), respectively, with robust rate capability and long-term cyclability. The distinct interfacial design strategy provides a new direction for designing compacted conversion-type anodes with superior lithium storage kinetics and stability for practical applications.