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• Zn-substituted Co 3 O 4 microspheres with a rough surface are synthesized. • Zn substitution modifies the lithium storage mechanism of Co 3 O 4 anodes. • The optimized sample exhibits good performance within half and full cells. Substituting Co 3 O 4 submicron spheres with Zn ions modifies the lithium storage mechanism, leading to an enhanced electrochemical performance. [Display omitted] Carbonaceous materials are used as the anode for rechargeable lithium-ion batteries (LIBs), however, lithium dendrites are easily formed during cycling due to the low lithium insertion potential (~0.1 V versus Li+/Li). As alternative anodes, transition metal oxides based on conversion mechanism have attached much attention. But the high lithiation potential (>1.0 V vs. Li+/Li) usually leads to a low output voltage and energy density when used in a full cell configuration. Herein, Zn-substituted Co 3 O 4 submicron spheres are successfully synthesized by a facile solvothermal reaction and subsequent calcination method. When used as the anode for LIB, the optimized sample shows a specific capacity of 686 mAh g−1 at 0.8 A g−1 after 500 cycles, and a specific capacity of 692.9 mAh g−1 at a higher current density of 3.2 A g−1 in a half-cell. Thanks to the controlled Zn substitution, the discharge voltage plateau is 0.16 V lower than that of the pure Co 3 O 4 anode at a current density of 0.4 A g−1. Further investigation of the 0.5Zn-Co 3 O 4 //LiCoO 2 full cells also displays a high capacity (400.7 mAh g−1 after 200 cycles at 0.4 A g−1) and an excellent rate capability (658.1 mAh g−1 at 1.6 A g−1) compared with the Co 3 O 4 //LiCoO 2 full cells. This work confirms that substituting suitable metal elements into sub-micron conversion based anodes can reduce the voltage plateau, which is of great significance for the practical applications in high performance energy storage devices. [ABSTRACT FROM AUTHOR]

Transition metal oxide (TMO) anodes show promising applications in energy storage due to the unique physical and chemical properties and high theoretical capacity to storage ions. Their practical usages are restricted by low intrinsic electronic conductivity, sluggish ionic diffusion, and large volume change during continuous cycling. In this work, we propose a strategy of selective solution-phase reduction on specific crystalline planes to generate the defect chemistry and thus improve the intrinsic electronic conductivity. Taking Co 3 O 4 electrode as a typical example, we prepared the structures with different exposed planes, which were then subjected to solution-phase reduction at room temperature. When used as the electrodes for lithium ion batteries, the optimized material possesses a high reversible capacity of 873.5 mAh g−1 at a current of 0.1 A g−1, even at a large current density of 5 A g−1, a remarkable discharge capacity of 569.1 mA h g−1 can still be achieved. The improved performance is attributed to the synergistic effects of the optimized amount of Co2+ species and oxygen vacancies. The current strategy can be extended to other TMO electrodes, paving an alternative way to optimize the electrochemical performance for different applications. Selective solution-phase reduction on specific exposed crystalline planes generates defect structures and thus improves the lithium storage properties in a given material. Image 1 • Exposed crystalline planes are selective reduced in solution. • Defect structures can be generated. • The optimized sample exhibits enhanced lithium storage properties. [ABSTRACT FROM AUTHOR]