Li-rich layered transition metal oxides are one of the most promising cathode materials for their high energy density.However,the cathodes usually suffer from severe potential dropping and capacity fading during cycli...Li-rich layered transition metal oxides are one of the most promising cathode materials for their high energy density.However,the cathodes usually suffer from severe potential dropping and capacity fading during cycling,which are associated with the surface oxygen release and accompanied by cation densification and structural collapse.Herein,an integrative approach of simultaneous constructing uniform 3d Fe-ion doping in the transition metal layer and Li-rich Li_(5)FeO_(4) shell to grab the oxygen and prevent interfacial side reactions is proposed.The introduction of Fe induces higher redox potential and stronger 3 d Fe-O_(2)p covalent bond,triggering reversible anionic redox via a reductive coupling mechanism.And the delithiated product of Li-rich Li_(5)FeO_(4) not only acts as a protective layer alleviating the side reactions but also enhances the surface kinetic property.With the benefit of promoted reversibility of oxygen redox and enhanced surface stability,the cathode exhibits high reversible capacity and superior cycle performance.Density function theory calculation indicates that the O_(2)p non-bonding state in the cathode incorporated with Fe sits at a lower energy band,resulting in higher energy storage voltage and improved oxygen stability.Consequently,the modified cathode exhibits a discharge specific capacity of 307 m A h g^(-1)(1 C=250 m A g^(-1)),coulombic efficiency of 82.09%in the initial cycle at 0.1 C and 88.34%capacity retention after 100 cycles at 1 C.The work illustrates a strategy that could simultaneously enhance oxygen redox reversibility and interface stability by constructing lattice bond coordination and delithiation induced protective layer to develop Li-rich materials with high reversible capacity and long lifespan.展开更多
Microstructure engineering serves as a potent approach to counteract the mechanical deterioration of Ni-rich layered cathodes,stemming from anisotropic strain during Lit(de)intercalation.However,a pressing challenge p...Microstructure engineering serves as a potent approach to counteract the mechanical deterioration of Ni-rich layered cathodes,stemming from anisotropic strain during Lit(de)intercalation.However,a pressing challenge persists in devising a direct method for fabricating radially aligned cathodes utilizing oriented hydroxide precursors.In this study,we synthesized LiNi_(0.92)Co_(0.04)Mn_(0.04)O_(2) oxides boasting superior radially aligned,sizerefined primary particles through a combination of strategic precipitation regulation and lithiation tuning.Elongated primary particles,achieved by stepwise control of ammonia concentration and pH during particle growth,facilitate the formation of radially aligned hydroxide precursor particles.Leveraging the size-refined and radially aligned primary particles,our prepared LiNi_(0.92)Co_(0.04)Mn_(0.04)O_(2) cathode exhibits a high discharge capacity of 229 mAh g^(-1) at 0.05 C,alongside excellent cycle stability,retaining 93.3% capacity after 200 cycles at 0.5 C(30℃)in a half cell,and 86.4% capacity after 1000 cycles at 1 C(30℃)in a full cell.Revisiting the regulation from precursor to oxide underscores the significance of controlling primary particles to maximize size perpendicular to[001]and attain suitable size along[001]during precursor precipitation and high-temperature calcination,offering valuable insights for synthesizing high-performance Ni-rich cathodes.展开更多
基金funded by the project from the national natural science foundation of China(21805018 and 21878195)the applied basic research project of Sichuan science and technology department(2020YJ0134)the everest scientific research program of chengdu university of technology。
文摘Li-rich layered transition metal oxides are one of the most promising cathode materials for their high energy density.However,the cathodes usually suffer from severe potential dropping and capacity fading during cycling,which are associated with the surface oxygen release and accompanied by cation densification and structural collapse.Herein,an integrative approach of simultaneous constructing uniform 3d Fe-ion doping in the transition metal layer and Li-rich Li_(5)FeO_(4) shell to grab the oxygen and prevent interfacial side reactions is proposed.The introduction of Fe induces higher redox potential and stronger 3 d Fe-O_(2)p covalent bond,triggering reversible anionic redox via a reductive coupling mechanism.And the delithiated product of Li-rich Li_(5)FeO_(4) not only acts as a protective layer alleviating the side reactions but also enhances the surface kinetic property.With the benefit of promoted reversibility of oxygen redox and enhanced surface stability,the cathode exhibits high reversible capacity and superior cycle performance.Density function theory calculation indicates that the O_(2)p non-bonding state in the cathode incorporated with Fe sits at a lower energy band,resulting in higher energy storage voltage and improved oxygen stability.Consequently,the modified cathode exhibits a discharge specific capacity of 307 m A h g^(-1)(1 C=250 m A g^(-1)),coulombic efficiency of 82.09%in the initial cycle at 0.1 C and 88.34%capacity retention after 100 cycles at 1 C.The work illustrates a strategy that could simultaneously enhance oxygen redox reversibility and interface stability by constructing lattice bond coordination and delithiation induced protective layer to develop Li-rich materials with high reversible capacity and long lifespan.
基金supported by project from the National Natural Science Foundation of China(21805018,22108218)by the Sichuan Science and Technology Program(2022ZHCG0018,2023NSFSC0117,2023ZHCG0060)+1 种基金the Yibin Science and Technology Program(2022JB005)project funded by the China Postdoctoral Science Foundation(2022M722704).
文摘Microstructure engineering serves as a potent approach to counteract the mechanical deterioration of Ni-rich layered cathodes,stemming from anisotropic strain during Lit(de)intercalation.However,a pressing challenge persists in devising a direct method for fabricating radially aligned cathodes utilizing oriented hydroxide precursors.In this study,we synthesized LiNi_(0.92)Co_(0.04)Mn_(0.04)O_(2) oxides boasting superior radially aligned,sizerefined primary particles through a combination of strategic precipitation regulation and lithiation tuning.Elongated primary particles,achieved by stepwise control of ammonia concentration and pH during particle growth,facilitate the formation of radially aligned hydroxide precursor particles.Leveraging the size-refined and radially aligned primary particles,our prepared LiNi_(0.92)Co_(0.04)Mn_(0.04)O_(2) cathode exhibits a high discharge capacity of 229 mAh g^(-1) at 0.05 C,alongside excellent cycle stability,retaining 93.3% capacity after 200 cycles at 0.5 C(30℃)in a half cell,and 86.4% capacity after 1000 cycles at 1 C(30℃)in a full cell.Revisiting the regulation from precursor to oxide underscores the significance of controlling primary particles to maximize size perpendicular to[001]and attain suitable size along[001]during precursor precipitation and high-temperature calcination,offering valuable insights for synthesizing high-performance Ni-rich cathodes.
