Journal
ADVANCED ENERGY MATERIALS
Volume 12, Issue 36, Pages -Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/aenm.202200519
Keywords
doping; electrical conductivity; fast-rechargeable lithium-ion batteries; ionothermal synthesis; lithium-ion diffusivity; Mo1 5W1 5Nb14O44
Categories
Funding
- U.S. Department of Energy's Office of Science, Office of Basic Energy Science, and Division of Materials Sciences Engineering [DE-AC05-00OR22725]
- U.S. Department of Energy [DE-AC05-00OR22725]
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In this study, a new doped material MWNO is prepared via an ionothermal-synthesis-assisted doping strategy, and its crystal structure and performance optimization mechanism are characterized. The results show that MWNO exhibits excellent fast-rechargeability and lithium-ion diffusivity, indicating its potential application.
Wadsley-Roth phased niobates are promising anode materials for lithium-ion batteries, while their inherently low electrical conductivity still limits their rate-capability. Herein, a novel doped Mo1.5W1.5Nb14O44 (MWNO) material is facilely prepared via an ionothermal-synthesis-assisted doping strategy. The detailed crystal structure of MWNO is characterized by neutron powder diffraction and aberration corrected scanning transmission electron microscope, unveiling the full occupation of Mo6+-dopant at the t1 tetrahedral site. In half-cells, MWNO exhibits enhanced fast-rechargeability. The origin of the improved performance is investigated by ultraviolet-visible diffuse reflectance spectroscopy, density functional theory (DFT) computation, and electrochemical impedance spectroscopy, revealing that bandgap narrowing improves the electrical conductivity of MWNO. Furthermore, operando X-ray diffraction elucidates that MWNO exhibits a typical solid-solution phase conversion-based lithium-ion insertion/extraction mechanism with reversible structural evolution during the electrochemical reaction. The boosted lithium-ion diffusivity of MWNO, due to the Mo6+/W6+ doping effect, is confirmed by a galvanostatic intermittent titration technique and DFT. With the simultaneously enhanced electrical conductivity and lithium-ion diffusivity, MWNO successfully demonstrates its fast-rechargeability and practicality in the LiNi0.5Mn1.5O4-coupled full-cells. Therefore, this work illustrates the potential of ionothermal synthesis in energy storage materials and provides a mechanistic understanding of the doping effect on improving material's electrochemical performance.
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