A one-step dynamic hydrothermal method for the synthesis of orthorhombic LiMnO2/CNTs nanocomposites networks for Li-ion batteries

Highlights: • Orthorhombic LiMnO₂/carbon nanotubes (CNTs) nanocomposites networks were prepared via dynamic hydrothermal route. • The composite with 5 wt% CNTs delivered specific capacity of 204.9 mAh g^-1 and 97.7% retention rate after 50 cycles. • GITT demonstrated the in-situ formed CNTs framework significantly improved lithium diffusion coefficient of o-LiMnO₂. -- Abstract: Orthorhombic LiMnO₂ (o-LiMnO₂) is considered as a potential cathode material for lithium ion batteries due to its high theoretical capacity and low cost. However, the irreversible phase transformation to spinel LiMn₂O₄ and sluggish lithium ion diffusion kinetics result in low practical specific capacity and poor cycling stability. In this work, conductive o-LiMnO₂/carbon nanotubes (CNTs) composites frameworks were constructed via an ingenious one-step dynamic hydrothermal method. The obtained o-LiMnO₂/CNTs composites achieved outstanding electrochemical performance upon adjustment of the CNTs content. The results demonstrated either physical introduction of 1 wt% CNTs into o-LiMnO₂ or in-situ formed o-LiMnO₂/CNTs composite with 0.5 wt% CNTs could improve electrochemical performance effectively compared with pristine o-LiMnO₂. However, when the content of CNTs increased to 1 wt% in in-situ formed o-LiMnO₂/CNTs, the specific capacity reached 194.4 mAh g⁻¹ and retention rate was 93.7% after 50 cycles at 0.1C. Moreover, the in-situ formed composite with 5 wt% CNTs led to the optimum specific capacity of 204.9 mAh g⁻¹ and a high capacity retention rate (97.7% after 50 cycles at 0.1C). Galvanostatic intermittent titration technique (GITT) measurement also demonstrated that 5 wt% CNTs in o-LiMnO₂/CNTs composite drastically improved the slowest Li⁺ diffusion step by a factor 100 times after 30 cycles as compared to the pristine counterpart. This behaviour demonstrated an accelerated diffusion of lithium through this new approach and improved reversibility of charging-discharging.