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216 results on '"Hai, Chunxi"'

27. Ball-Milling-Assisted N/O Codoping for Enhanced Sodium Storage Performance of Coconut-Shell-Derived Hard Carbon Anodes in Sodium-Ion Batteries

Author

Xiang, Jiaxing, Ma, Luxiang, Sun, Yanxia, Dong, Shengde, Xu, Qi, He, Xin, Zhou, Yuan, and Hai, Chunxi

Abstract

Sodium-ion batteries (SIBs) are regarded as cost-effective alternatives or competitors to lithium-ion batteries for large-scale electric energy storage applications. However, their development has been hindered by the high cost of hard carbon (HC) anodes and poor electrochemical performance. To enhance the sodium storage capacity and rate performance of HC, this study accelerated the electrochemical performance of coconut-shell-derived HC anodes for SIBs through N/O codoping using ball milling and pyrolysis. Experimental results demonstrate that the simultaneous introduction of N and O generates a synergistic effect, increasing the surface oxygen-containing functional groups, defects, and interlayer spacing of coconut-shell-derived HC through the codoping of light elements. The excellent strategy has increased the slope capacity and platform capacity of HC, and the synergistic modification of N/O has increased its reversible specific capacity from 272 to 343 mA h g–1(30 mA g–1), with a retention rate of approximately 92.1% after 100 cycles. In addition, it also exhibits an excellent rate performance, reaching 178 mA h g–1at 1500 mA g–1. In summary, this study presents an effective strategy for modifying biomass-derived HC.

Published
2024
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28. Improving the Cycle Stability of LiNiO2through Al3+Doping and LiAlO2Coating

Author

Leng, Yue, Dong, Shengde, Chen, Zhan, Sun, Yanxia, Xu, Qi, Ma, Luxiang, He, Xin, Hai, Chunxi, and Zhou, Yuan

Abstract

In this study, we addressed the poor cycling and rate performance of LiNiO2, a material with ultrahigh nickel content considered a strong contender for high-energy-density lithium-ion battery cathodes. We introduced nano-Al2O3during the lithiation process to achieve dual modified material through bulk phase element doping and in situ LiAlO2coating. Comparison revealed notable improvements in the modified materials. In particular, LiNi0.99Al0.01O2maintained a capacity retention rate of 73.1% after 300 cycles in a long-cycle test at 0.5C current density, outperforming the undoped material. In rate performance tests, the doped samples consistently exhibited higher discharge-specific capacities than that of the undoped counterpart. Notably, at a high current density of 5C, LiNi0.99Al0.01O2exhibited a discharge-specific capacity of 101.75 mAh g–1. The results indicate that an appropriate amount of Al doping can effectively stabilize the layered structure of the cathode material and delay the irreversible phase transition from H2 to H3. Further, Al doping facilitates the formation of a LiAlO2coating on the surface of the particles. This coating acts as a fast-ion conductor, enhancing the transport of lithium ions and reducing the erosion of the active material by the electrolyte.

Published
2024
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