Co–B Nanoflakes as Multifunctional Bridges in ZnCo ₂ O ₄ Micro-/Nanospheres for Superior Lithium Storage with Boosted Kinetics and Stability

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 ZnCo ₂ O ₄ micro-/nanospheres, a compacted ZnCo ₂ O ₄ /Co–B hybrid structure is constructed. Co–B nanoflakes not only bridge ZnCo ₂ O ₄ nanoparticles and function as anchors for ZnCo ₂ O ₄ micro-/nanospheres 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 ZnCo ₂ O ₄ /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.