Nickel(Ni)-rich layered materials have attracted considerable interests as promising cathode materials for lithium ion batteries(LIBs)owing to their higher capacities and lower cost.Nevertheless,Mn-rich cathode materi...Nickel(Ni)-rich layered materials have attracted considerable interests as promising cathode materials for lithium ion batteries(LIBs)owing to their higher capacities and lower cost.Nevertheless,Mn-rich cathode materials usually suffer from poor cyclability caused by the unavoidable side-reactions between Ni^4+ions on the surface a nd electrolytes.The design of gradient concentration(GC)particles with Ni-rich inside and Mn-rich outside is proved to be an efficient way to address the issue.Herein,a series of LiNi0.6Co0.2Mn0.2O2(LNCM 622)materials with different GCs(the atomic ratio of Ni/Mn decreasing from the core to the outer layer)have been successfully synthesized via rationally designed co-precipitation process.Experimental results demonstrate that the GC of LNCM 622 materials plays an important role in their microstructure and electrochemical properties.The as-prepared GC3.5 cathode material with optimal GC can provide a shorter pathway for lithium-ion diffusion and stabilize the near-surface region,and finally achieve excellent electrochemical performances,delivering a discharge capacity over 176 mAh·g^-1 at 0.2 C rate and exhibiting capacity retention up to 94%after 100 cycles at 1 C.T h e rationally-designed co-precipitation process for fabricating the Ni-rich layered cathode materials with gradient composition lays a solid foundation for the preparation of high-performance cathode materials for LIBs.展开更多
Multiwalled carbon nanotubes (MWNTs) were used as the conductive additive in the electrode materials. The electrochemical properties of supercapacitors based on LiNi0.8Co0.2O2 / MWNTs composite and LiNi0.8Co0.2O2/acet...Multiwalled carbon nanotubes (MWNTs) were used as the conductive additive in the electrode materials. The electrochemical properties of supercapacitors based on LiNi0.8Co0.2O2 / MWNTs composite and LiNi0.8Co0.2O2/acetylene black composite and MWNTs in 1.0 mol·L-1 LiClO4 / EC+DEC [V(EC)∶V(DEC)=1∶1] electrolyte were investigated by means of constant charge/discharge current tests, respectively. The experimental results show that the LiNi0.8Co0.2O2 / MWNTs composite has better performance than that of others, and the maximum specific capacitance of the supercapacitor can reach 271.6 F·g-1, while the energy density is up to 339.5 Wh·kg-1. Furthermore, it is remarkable that the performance of MWNTs is better than that of acetylene black as the conductive additive.展开更多
基金the financial support of the National Natural Science Foundation of China(Grant Nos.91834301,91534102 and 21271058)Science and Technology Project of Anhui Province(Nos.201903a05020021 and 17030901067).
文摘Nickel(Ni)-rich layered materials have attracted considerable interests as promising cathode materials for lithium ion batteries(LIBs)owing to their higher capacities and lower cost.Nevertheless,Mn-rich cathode materials usually suffer from poor cyclability caused by the unavoidable side-reactions between Ni^4+ions on the surface a nd electrolytes.The design of gradient concentration(GC)particles with Ni-rich inside and Mn-rich outside is proved to be an efficient way to address the issue.Herein,a series of LiNi0.6Co0.2Mn0.2O2(LNCM 622)materials with different GCs(the atomic ratio of Ni/Mn decreasing from the core to the outer layer)have been successfully synthesized via rationally designed co-precipitation process.Experimental results demonstrate that the GC of LNCM 622 materials plays an important role in their microstructure and electrochemical properties.The as-prepared GC3.5 cathode material with optimal GC can provide a shorter pathway for lithium-ion diffusion and stabilize the near-surface region,and finally achieve excellent electrochemical performances,delivering a discharge capacity over 176 mAh·g^-1 at 0.2 C rate and exhibiting capacity retention up to 94%after 100 cycles at 1 C.T h e rationally-designed co-precipitation process for fabricating the Ni-rich layered cathode materials with gradient composition lays a solid foundation for the preparation of high-performance cathode materials for LIBs.
文摘Multiwalled carbon nanotubes (MWNTs) were used as the conductive additive in the electrode materials. The electrochemical properties of supercapacitors based on LiNi0.8Co0.2O2 / MWNTs composite and LiNi0.8Co0.2O2/acetylene black composite and MWNTs in 1.0 mol·L-1 LiClO4 / EC+DEC [V(EC)∶V(DEC)=1∶1] electrolyte were investigated by means of constant charge/discharge current tests, respectively. The experimental results show that the LiNi0.8Co0.2O2 / MWNTs composite has better performance than that of others, and the maximum specific capacitance of the supercapacitor can reach 271.6 F·g-1, while the energy density is up to 339.5 Wh·kg-1. Furthermore, it is remarkable that the performance of MWNTs is better than that of acetylene black as the conductive additive.
