Although lithium(Li)metal delivers the highest theoretical capacity as a battery anode,its high reactivity can generate Li dendrites and"dead"Li during cycling,resulting in poor reversibility and low Li util...Although lithium(Li)metal delivers the highest theoretical capacity as a battery anode,its high reactivity can generate Li dendrites and"dead"Li during cycling,resulting in poor reversibility and low Li utilization.Inducing uniform Li plating/stripping is the core of solving these problems.Herein,we design a highly lithiophilic carbon film with an outer sheath of the nanoneedle arrays to induce homogeneous Li plating/stripping.The excellent conductivity and 3D framework of the carbon film not only offer fast charge transport across the entire electrode but also mitigate the volume change of Li metal during cycling.The abundant lithiophilic sites ensure stable Li plating/stripping,thereby inhibiting the Li dendritic growth and"dead"Li formation.The resulting composite anode allows for stable Li stripping/plating under 0.5 mA cm^(-2) with a capacity of 0.5 mA h cm^(-2) for 4000 h and 3 mA cm^(-2) with a capacity of3 mA h cm^(-2) for 1000 h.The Ex-SEM analysis reveals that lithiophilic property is different at the bottom,top,or channel in the structu re,which can regulate a bottom-up uniform Li deposition behavior.Full cells paired with LFP show a stable capacity of 155 mA h g^(-1) under a current density of 0.5C.The pouch cell can keep powering light-emitting diode even under 180°bending,suggesting its good flexibility and great practical applications.展开更多
Lithium cobalt oxide(LCO),the first commercialized cathode active material for lithium-ion batteries,is known for high voltage and capacity.However,its application has been limited by relatively low capacity and stabi...Lithium cobalt oxide(LCO),the first commercialized cathode active material for lithium-ion batteries,is known for high voltage and capacity.However,its application has been limited by relatively low capacity and stability at high C-rates.Reducing particle size is considered one of the most straightforward and effective strategies to enhance ion transfer,thus increasing the rate performance.However,side reactions are simultaneously enhanced as the specific surface area increases.Herein,we investigate the impact of LCO particles with varying size distributions and optimize the particle size.To modulate the side reactions associated with particle size reduction,an ultrathin carbon nanotube film(UCNF)is introduced to coat the cathode surface.With this simple process and optimized particle size,the rate performance improves significantly,normal commercial LCO achieves 118 mA·h·g^(−1)at 3.0–4.3 V and 20 C(0.72 mA·h·cm^(−2)),corresponding to power density of 8732 W·kg^(−1).This method is applied to high voltage as well,152 mA·h·g^(−1)at 3.0–4.6 V and 20 C(0.99 mA·h·cm^(−2))was achieved with high-voltage LCO(HVLCO),corresponding to power density of 11,552 W·kg^(−1).The cycling stability is also enhanced,with the capacity retention maintaining more than 96%after 100 cycles at 0.1 C.For the first time,UCNF is demonstrated to suppress the excessive decomposition of the electrolytes and solvents by blocking electron injection/extraction between LCO and electrolyte solution.Our findings provide a simple method for improving LCO rate performance,especially at high C-rates.展开更多
Gradient composites, LiNi1-yCoyO2, are synthesized from coated spherical Ni(OH)2 precursor. These compos-ites could be applied as new cathode materials in lithium-ion batteries because they have low cobalt content (y...Gradient composites, LiNi1-yCoyO2, are synthesized from coated spherical Ni(OH)2 precursor. These compos-ites could be applied as new cathode materials in lithium-ion batteries because they have low cobalt content (y≤0.2) and exhibit excellent properties during high-rate charge/discharge cycles. The initial discharge capacity of coated composite of LiNi0.95Co0.05O2 is 186 mAh/g, and the decreasing rate of the capacity is 3.2% in 50 cycles at 1 C rate. It has been verified by TEM and EDX experiments that a core-shell structure of the composite particles develops because of the cobalt enrichment near the surfaces, and the formation of the cobalt enrichment layer is sensitive to sintering temperature. High cobalt surface concentration may reduce the undesired reactions and stabilize the struc-ture of the particles.展开更多
LiNi1-xCoxO2 cathode materials for lithium ion batteries were synthesized by the co-precipitation and solid-state reaction methods with LiOH·H2O, Ni(NO3)2·6H2O and Co(NO3)2·6H2O as raw materials. The ma...LiNi1-xCoxO2 cathode materials for lithium ion batteries were synthesized by the co-precipitation and solid-state reaction methods with LiOH·H2O, Ni(NO3)2·6H2O and Co(NO3)2·6H2O as raw materials. The materials were characterized by XRD, SEM and electrochemical tests. The results showed that synthesized cathode materials were with layered structure similar to α-NaFeO2 and uniform morphology and nearly normal grain size distribution and better electrochemical performance when x was 0.18. The first charge and discharge capacity of the cathode material was 224.3 mAh·g-1 and 194.2 mAh·g-1, respectively. 88.5% of the first discharge capacity remained at the 20th cycle.展开更多
基金supported by the National Natural Science Foundation of China(31870570)the Science and Technology Plan of Fujian Provincial,China(2020H4026,2022G02020 and 2022H6002)+1 种基金the Science and Technology Plan of Xiamen(3502Z20203005)the Scientific Research Start-up Funding for Special Professor of Minjiang Scholars。
文摘Although lithium(Li)metal delivers the highest theoretical capacity as a battery anode,its high reactivity can generate Li dendrites and"dead"Li during cycling,resulting in poor reversibility and low Li utilization.Inducing uniform Li plating/stripping is the core of solving these problems.Herein,we design a highly lithiophilic carbon film with an outer sheath of the nanoneedle arrays to induce homogeneous Li plating/stripping.The excellent conductivity and 3D framework of the carbon film not only offer fast charge transport across the entire electrode but also mitigate the volume change of Li metal during cycling.The abundant lithiophilic sites ensure stable Li plating/stripping,thereby inhibiting the Li dendritic growth and"dead"Li formation.The resulting composite anode allows for stable Li stripping/plating under 0.5 mA cm^(-2) with a capacity of 0.5 mA h cm^(-2) for 4000 h and 3 mA cm^(-2) with a capacity of3 mA h cm^(-2) for 1000 h.The Ex-SEM analysis reveals that lithiophilic property is different at the bottom,top,or channel in the structu re,which can regulate a bottom-up uniform Li deposition behavior.Full cells paired with LFP show a stable capacity of 155 mA h g^(-1) under a current density of 0.5C.The pouch cell can keep powering light-emitting diode even under 180°bending,suggesting its good flexibility and great practical applications.
基金supported by the National Key R&D Program of China(Nos.2018YFA0208402 and 2020YFA0714700)the National Natural Science Foundation of China(Nos.11634014 and 51372269)the“Strategic Priority Research Program”of the Chinese Academy of Sciences(No.XDA09040202).
文摘Lithium cobalt oxide(LCO),the first commercialized cathode active material for lithium-ion batteries,is known for high voltage and capacity.However,its application has been limited by relatively low capacity and stability at high C-rates.Reducing particle size is considered one of the most straightforward and effective strategies to enhance ion transfer,thus increasing the rate performance.However,side reactions are simultaneously enhanced as the specific surface area increases.Herein,we investigate the impact of LCO particles with varying size distributions and optimize the particle size.To modulate the side reactions associated with particle size reduction,an ultrathin carbon nanotube film(UCNF)is introduced to coat the cathode surface.With this simple process and optimized particle size,the rate performance improves significantly,normal commercial LCO achieves 118 mA·h·g^(−1)at 3.0–4.3 V and 20 C(0.72 mA·h·cm^(−2)),corresponding to power density of 8732 W·kg^(−1).This method is applied to high voltage as well,152 mA·h·g^(−1)at 3.0–4.6 V and 20 C(0.99 mA·h·cm^(−2))was achieved with high-voltage LCO(HVLCO),corresponding to power density of 11,552 W·kg^(−1).The cycling stability is also enhanced,with the capacity retention maintaining more than 96%after 100 cycles at 0.1 C.For the first time,UCNF is demonstrated to suppress the excessive decomposition of the electrolytes and solvents by blocking electron injection/extraction between LCO and electrolyte solution.Our findings provide a simple method for improving LCO rate performance,especially at high C-rates.
文摘Gradient composites, LiNi1-yCoyO2, are synthesized from coated spherical Ni(OH)2 precursor. These compos-ites could be applied as new cathode materials in lithium-ion batteries because they have low cobalt content (y≤0.2) and exhibit excellent properties during high-rate charge/discharge cycles. The initial discharge capacity of coated composite of LiNi0.95Co0.05O2 is 186 mAh/g, and the decreasing rate of the capacity is 3.2% in 50 cycles at 1 C rate. It has been verified by TEM and EDX experiments that a core-shell structure of the composite particles develops because of the cobalt enrichment near the surfaces, and the formation of the cobalt enrichment layer is sensitive to sintering temperature. High cobalt surface concentration may reduce the undesired reactions and stabilize the struc-ture of the particles.
文摘LiNi1-xCoxO2 cathode materials for lithium ion batteries were synthesized by the co-precipitation and solid-state reaction methods with LiOH·H2O, Ni(NO3)2·6H2O and Co(NO3)2·6H2O as raw materials. The materials were characterized by XRD, SEM and electrochemical tests. The results showed that synthesized cathode materials were with layered structure similar to α-NaFeO2 and uniform morphology and nearly normal grain size distribution and better electrochemical performance when x was 0.18. The first charge and discharge capacity of the cathode material was 224.3 mAh·g-1 and 194.2 mAh·g-1, respectively. 88.5% of the first discharge capacity remained at the 20th cycle.
