Chao Chen,Ming Xu,Kai Zhang,Hao An,Gang Zhang,Bo Hong,Jie Li,Yanqing Lai
The Ni-rich layered oxide (NLO) cathode materials play a key role in developing high-energy-density lithium ion battery (LIB) for wide scale deployment of clean transportation technologies. However, surface reconstruction from a layered structure to a mixed spinel/rock-salt structure during charge/discharge cycles is related to the severe voltage decay and capacity fading of the stoichiometric NLO cathode materials, thus thwarting the practical implementation. Herein, we report a heterostructured NLO cathode that tackles the structural degradation and related voltage decay problems. The efficient internal “incore” volumetric heating by direct coupling of microwave energy induces formation of Ni, Co-rich core and Al-rich shell. As a result of the encapsulation of the atomically ordered NiAl 2 O 4 after heat treatment, the solid/electrolyte interphase and surface structure of NLO cathode remains stable. By applying this NiAl 2 O 4 /NLO heterostructured material as a cathode, we demonstrate its robustness in suppressing the voltage decay (0.8% after 100 cycles) during high-voltage cell operation. Rather than the typical modifications, our work explores a more efficient structure engineering process for applications in nano-/micro-manufacturing transition-metal based electrode materials and sheds light on developing high-performance LIB in the near future.
Yi Lin,Zaixing Wang,Lina Tang,Shi Jiang,Yu Guo,Xiaoqin Liu
Ni-based catalysts supported on composite metal oxides (NiO-Al 2 O 3 , MgO-Al 2 O 3 , Co 3 O 4 -Al 2 O 3 ) were synthesized via coprecipitation followed by Ni impregnation to investigate the influence of support composition on catalyst stability in methane steam reforming. Accelerated deactivation protocols (methane decomposition, high-temperature sintering, hydrothermal oxidation) revealed hydrothermal oxidation as the primary cause of irreversible deactivation. The 10Ni/NiAl catalyst (10 wt% Ni/10 wt% NiO-Al 2 O 3 ) showed remarkable regenerability after 923 K hydrothermal treatment, fully restoring its activity. This was attributed to coexisting reduced Ni species and readily reducible NiO, facilitating rapid reactivation. Other catalysts formed thermally stable NiAl 2 O 4 , leading to permanent deactivation. Methane cracking at 973 K had negligible effect, and 10Ni/NiAl catalyst exhibited the lowest carbon deposition (17.02 %). Under extreme hydrogen purged at 1223 K, only the 10Ni/CoAl catalyst exhibited a minor activity decline. The superior stability of 10Ni/NiAl was attributed to an in situ-formed NiAl composite metal oxides during 973 K calcination, which effectively anchored Ni particles, suppressed sintering, and prevented extensive oxidation.
危险品化学品经营许可证（带存储）