Al has been considered as a promising Li-ion batteries anode. However, the volume expansion always makes the electrode in an unstable structure. Meanwhile, the natural Al 2 O 3 passivation layer may lead to a large voltage dip, which could interrupt the lithiation process and result in a limited capacity. Herein, we report a neat avenue to activate the commercial Al pellet electrode by replacing the Al 2 O 3 layer with Sn at room temperature. Not any acid or tedious process is needed. Benefiting from the elimination of Al 2 O 3 and high electrochemical-activity of Sn, the obtained Al@Sn pellet electrode delivers a reversible capacity of 959.5 mAh g −1 at 0.1 A g −1 , which is larger than that (395.7 mAh g −1 ) of the commercial Al pellet electrode and approaches the calculated theoretical capacity. Notably, the voltage dip is muchly lowered to 0.03 V from 0.1 V. When graphene oxide (GO) was further attached for relieving the volume expansion, the as-prepared Al@Sn@GO pellet electrode presents astonishing Li-ion storage properties both in half and full batteries. This work demonstrates that the cooperation of the Al 2 O 3 elimination and matrix addition is successful in promoting the Li-ion storage properties of Al anode, presenting an attractive vision for the development of practical Al-based anodes.
Li metal anode is deemed the most promising candidate anode for high-energy battery systems such as Li-sulfur and Li-fluoride batteries. However, some severe challenges, for example, facile formation and growth of Li dendrites, large volume evolution of hostless Li ,and low Coulombic efficiency of Li plating/stripping, still hinder the commercialization of Li-metal batteries (LMBs). Herein, a free-standing and highly flexible 3D current collector made of carbon nanofibers (CNFs) conformally coated by continuous Sn layer is synthesized by electrospinning method. Sn layer enables a lithiophilic and alloyable carbon skeleton surface and provides uniform and continuous Li nucleation sites, leading to unusual conformal Li plating behavior and effective inhibition of Li dendrites. The spatial confinement of Li plating mitigates the volume expansion and network distortion of CNFs. The electric contact reinforced by Sn interlayer achieves highly reversible Li stripping for more than 850 h for CNF-Sn@Li symmetric cell. The small nucleation overpotential (28 mV) and potential polarization (14 mV for symmetric cell) benefit from the low energy barrier of Li–Sn alloying and following Li nucleation on Li–Sn layer. For CNF-Sn@Li-LiFePO4 full cell, the capacity retention ratio is as high as 92.2% after 150 cycles at 0. 5C and the reversible capacities are maintained at 134.3 and 106.7 mAh g–1 at 2C and 5C respectively. The design of 3D lithiophilic current collector instead of planar Cu is a potential solution to highly safe LMBs.
Yang Li,Kai Li,Bin Hu,Zhen-xi Zhang,Guan Zhang,Shi-yu Feng,Ti-peng Wang,Qiang Lu
As a value-added chiral chemical, 1-hydroxy-3,6-dioxobicyclo[3.2.1]oct-2-one (LAC) can be obtained via cellulose pyrolysis, but its yield is extremely low in the conventional pyrolysis process. Herein, novel nickel-tin layered double oxide (NiSn-LDO) catalysts were developed for the selective production of LAC from the in-situ catalytic fast pyrolysis (CFP) of cellulose. Several layered double oxides (LDOs) were prepared and evaluated via pyrolysis-chromatography/mass spectrometry (Py-GC/MS) tests for the in-situ CFP of cellulose. NiSn-LDO was determined as the most capable catalyst for selective LAC preparation, and further experiments were conducted to confirm the optimal condition to produce LAC over several essential factors of reaction temperature, Ni/Sn molar ratio in the NiSn-LDO catalyst, and catalyst-to-cellulose (CA-to-CL) ratio. The results demonstrated that LAC was sensitive to the reaction conditions, and its yield always exhibited the tide of first increasing followed with decreasing along with the increase of pyrolysis temperature, Ni/Sn molar ratio, and CA-to-CL ratio. The maximal LAC yield reached 9.11 wt% over the pyrolysis temperature of 320 °C using NiSn-LDO with a Ni/Sn molar ratio of 2/1 at the CA-to-CL ratio of 1/1, which was more than 5 times of that from the non-catalytic process (1.72 wt%). In addition, the NiSn-LDOs possessed much better catalytic capability to yield LAC with high selectivity than previously reported catalysts.
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