Surface-Modified Lithiated H2V3O8: A Stable High Energy Density Cathode Material for Lithium-Ion Batteries with LiPF6 Electrolytes

A new one-pot multistep process was developed to coat and stabilize LixH2V3O8 as cathode material for Li-ion batteries with LiPF6-based electrolyte. The crystal structure of LixH2V3O8 was preserved after depositing an amorphous AlOx(OH)(y) coating. The sample containing higher aluminum content (3 wt 96 nominal) revealed a homogeneous surface coverage with 3 to 10 nm thickness, whereas for lower aluminum content no clear coverage could be detected by imaging. Spectroscopic techniques were used to confirm the presence of aluminum in all coatings. The electrochemical characterization of LixH2V3O8 cathodes coated with AlOx(OH)(y) containing 1.5 wt 96 nominal aluminum showed higher stability for lithium-ion intercalation compared to that of bare LixH2V3O8. For instance, after 200 cycles this material revealed 89% capacity retention compared to 67% for uncoated LixH2V3O8. These results enabled the preparation of cathodes working below 4.2 V with a specific energy higher that 0.5 Wh kg(-1) for more than 200 cycles.