Preparation And Lithium Storage Properties Of Carbon Modified Li₃VO₄ Microspheres Composites

Now,lithium-ion batteries?LIBs?have been widely used in various aspects of society.However,the energy density and working lifespan of LIBs always are two major barriers limiting their rapid development.Intercalation anode materials for LIBs usually have higher structural reversibility,which is the main reason for successful application in commercial LIBs.But graphite and Li₄Ti₅O₁₂ as two traditional anode materials exhibit the relatively low capacities and the unsatisfactory Li⁺insertion potentials.Therefore,it is urgent to develop an anode material with lower cost,higher capacity,and more suitable Li⁺insertion potential.This paper focused on Li₃VO₄ as an anode material for LIBs,which has high theoretical capacity,suitable Li⁺insertion potential,and excellent ionic conductivity.This work aims to improve its poor electronic conductivity and alleviate the volume change under deep discharge/charge conditions.Therefore,Li₃VO₄/C/rGO composite with delicate structure was fabricated through a scalable method.Meanwhile,the relationship between structure and properties was elucidated by the combination of basic characterization techniques and electrochemical measurements.Furthermore,the lithium storage mechanism of Li₃VO₄ was revealed by in-situ XRD technique.The main conclusions of this paper are summarized as follows:?1?Based on the carbon decoration strategy,Li₃VO₄-based materials?such as deflated balloon-like Li₃VO₄/C/rGO microspheres?were prepared through a facile spray-drying method.The three-dimensional continuous electronic transport pathways in Li3VO4/C/rGO microspheres effectively improve the electronic conductivity of Li₃VO₄,and sufficient free space in its inner is very beneficial to alleviate the volume change effect.?2?The lithium storage process of Li₃VO₄-based materials was analyzed,and the electrochemical performances of these materials were compared in the shallow discharge/charge potential window?0.2–3.0 V?.Moreover,the relationship between electrochemical performances and structure of Li₃VO₄/C/rGO was studied under the deep discharge/charge conditions?0.02–3.0 V?.The experimental results indicated that the deflated balloon-like Li3VO4/C/rGO microspheres can exhibit a high intercalation capacity of 591 mAh g^-1 and achieve a reversible capacity of 560 mAh g^-1 after 100 cycles at 100 mA g^-1,while it can maintain 350 mAh g^-1 after 1000 cycles at 2000 mA g^-1.With high capacity and outstanding stability,Li₃VO₄/C/rGO outperforms other intercalation anode materials?such as graphite,Li4Ti5O12,and TiO2?.?3?In addition,in-situ XRD technique was applied to understand the lithium storage mechanism of Li₃VO₄/C/rGO in the deep discharge/charge potential window of 0.02–3.0 V.The reversible lithium storage process of Li3VO4/C/rGO was achieved through the combination of solid-solution reaction and two-phase reaction mechanism.Finally,Li₃VO₄/C/rGO//LiNi_0.8Co_0.15Al_0.05O₂ full cell with high specific capacity and good cyclability was successfully assembled,which demonstrated Li3VO4/C/rGO is a promising anode candidate for the next-generation high-performance LIBs.