The fabrication of silicon (Si) anode materials derived from high silica‐containing plants enables effective utilization of subsidiary agricultural products. However, the electrochemical performances ...of synthesized Si materials still require improvement and thus need further structural design and morphology modifications, which inevitably increase preparation time and economic cost. Here, the conversion of corn leaves into Si anode materials is reported via a simple aluminothermic reduction reaction without other modifications. The obtained Si material inherits the structural characteristics of the natural corn leaf template and has many inherent advantages, such as high porosity, amorphous/crystalline mixture structure, and high‐valence SiOx residuals, which significantly enhance the material's structural stability and electrode adhesive strength, resulting in superior electrochemical performances. Rate capability tests show that the material delivers a high capacity of 1200 mA h g−1 at 8 A g−1 current density. After 300 cycles at 0.5 A g−1, the material maintains a high specific capacity of 2100 mA h g−1, with nearly 100% capacity retention during long‐term cycling. This study provides an economical route for the industrial production of Si anode materials for Lithium‐Ion batteries.
Si anode material derived from corn leaves inherits structural characteristics of the corn leaf template and has many inherent advantages such as high porosity, amorphous/crystalline mixture structure, and high‐valence SiOx residuals, which significantly enhance the material's structural stability and electrode adhesive strength, resulting in superior electrochemical performances.
As one of the highest specific capacity anode materials in lithium-ion batteries, the main technical issue for silicon (Si) based electrodes is the rapid capacity fading caused by the huge volume ...changes. Porous Si materials are reported to efficiently alleviate the side effects of volume fluctuation. However, the expensive precursor and complicated production process in previous reports limited their practical applications. Herein, we report a cost-efficient approach on the fabrication of porous Si via the low temperature aluminothermic reduction of low cost natural raw materials, combining the advantages of low temperature and natural materials. The porous structure of attapulgite-derived Si (SiATP) is well retained during the compositing process. The obtained composite electrode SiATP/graphite@carbon (SiATP/G@C) exhibits excellent electrochemical performance, with a reversible discharge capacity of 799 mAh g−1 after 100 cycles. To demonstrate the versatility of the approach, another natural ore, mica (MIC), was also utilized to the fabrication of porous Si (SiMIC). As expected, the SiMIC/graphite@carbon composite electrode also exhibits high specific capacity (697 mAh g−1 after 100 cycles), superior capacity retention (81% after 100 cycles based the 4th cycle), and outstanding rate capability.
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•·low-cost SiOx/C composites are in situ controllable constructed from commercial bamboo charcoal.•·Composite possess a well-reserved porous and hierarchical structure.•·It exhibits ...high capacity with good cyclic stability in half/full LIBs.
Ongoing pursuit of high performance functional materials from natural and inexpensive resources receive continuous attention. 3D porous SiOx/C composites are constructed only from commercial bamboo charcoal via an in situ top-down synthetic route involving activated carbonization and mild aluminothermic reduction. Particularly, the obtained composites possess a well-reserved porous and hierarchical structure where SiOx nanoparticles are embedded in the entire 3D carbon framework. When used as the active material for lithium-ion battery anode, the optimized SC-3 sample achieves the impressive specific capacity (1100 mA h g−1) at 200 mA g−1 after 300 cycles, as well as prominent cyclic stability under 1 A g−1 (700 mA h g−1 after 200 cycles). Besides, this SiOx/C anode demonstrates perfect capacity retentions and superior cyclic stability in full cells. This low cost bamboo-derived composite can further broaden the vision of advancing new-generation anode materials for rechargeable batteries and the related hierarchical composites.
Two‐dimensional (2D) monometallic pnictogens (antimony or Sb, and bismuth or Bi) nanosheets demonstrate potential in a variety of fields, including quantum devices, catalysis, biomedicine and energy, ...because of their unique physical, chemical, electronic and optical properties. However, the development of general and high‐efficiency preparative routes toward high‐quality pnictogen nanosheets is challenging. A general method involving a molten‐salt‐assisted aluminothermic reduction process is reported for the synthesis of Sb and Bi nanosheets in high yields (>90 %). Electrocatalytic CO2 reduction was investigated on the Bi nanosheets, and high catalytic selectively to formate was demonstrated with a considerable current density at a low overpotential and an impressive stability. Bi nanosheets continuously convert CO2 into formate in a flow cell operating for one month, with a yield rate of 787.5 mmol cm−2 h−1. Theoretical results suggest that the edge sites of Bi are far more active than the terrace sites.
A low‐temperature molten‐salt‐assisted method to synthesize nanosheet‐like monometallic antimony or bismuth with high‐yield has been developed. The obtained bismuth nanosheets can effectively and continuously electrocatalyze the reduction of CO2 to formate with a stability of more than one month.
Industrial experiments were carried out for Mg production by aluminothermic process in industrial retorts and the factors affecting the reduction efficiency were analyzed. The results show that the ...main factors reducing the reduction ratio are oxidation and combustion of crystallized magnesium and uneven mixing of raw materials. The latter could result in raw material regions with low Al concentration and MgO redundance, which can promote the formation of 12CaO·7Al2O3 and CaO·Al2O3. For raw material regions with higher Al concentration, both MgO and CaO can be reduced to form the Mg2Ca phase. Radiation and chemical reaction heat are the key factors affecting the reaction rate. Increasing the heating temperature can rapidly increase the bed temperature and obtain sufficient reaction ratio. The higher the magnesium content in the pellets is, the longer the reduction time is required.
Electroplating sludge is extensively produced in chemical precipitation–based treatment of electroplating wastewater. It poses a huge threat to environmental safety if not properly disposed, ascribed ...to its high contents of heavy metals. An innovative metallurgical approach was proposed a to recycle Cu, Cr, and Ni from it. Ammonia leaching was firstly performed to selectively leach Cu from Cr, in which the Cu oxide and sulfide were leached into the leachate while the Cr oxide and Ni carbide (NiCx) retained in the residue. (NH4)2SO4 increased the Cu leaching rate via increasing the dissolved oxygen amount in the ammonia leachate and converting CuS to Cu2+. Under the optimal conditions, the leaching efficiency of Cu achieved 96.5 % while that of Cr was only 0.1 %. In the followed aluminothermic reduction, C in the leaching residue could be effectively removed via a thermal oxidation, which in turn decreased the formation of a C-containing compound of high melting point and benefited the Cr and Ni recovery. Cr and Ni from the residue were reduced and recovered in a Cr-Ni alloy, and the reductant of Al first changed to a refractory Al2O3 and then transformed to a low melting point 12CaO·7Al2O3 with the additive of CaO. This transformation increased the molten slag fluidity and promoted the separation of Cr-Ni alloy from slag. Moreover, the excessive Al increased the Cr and Ni yields and concentrated all of them to be together. Partial Al was used as reductant, and the other Al transferred into Cr-Ni alloy to decrease its melting point. Cr and Ni contents in the smelting slag could be decreased to 0.11 wt% and 0.12 wt% respectively, showing an efficient recovery. This work provided a high efficiency method to recover Cu, Cr, and Ni from waste electroplating sludge.
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•Cu, Ni, and Cr can be effectively separated and recovered from electroplating sludge.•NH3 leaching can selectively leach Cu from Cr, realizing a separation and Cu recycle.•Cr & Ni were reduced and recovered in a sole alloy ingot in aluminothermic reduction.•CaO changed Al2O3 to 12CaO·7Al2O3, promoting Ni-Cr alloy separation from molten slag.•Excess Al reduced Ni-Cr alloy melting point and aggregated alloy particles together.
Microsized porous SiOx@C composites used as anode for lithium-ion batteries (LIBs) are synthesized from rice husks (RHs) through low-temperature (700 °C) aluminothermic reduction. The resulting ...SiOx@C composite shows mesoporous irregular particle morphology with a high specific surface area of 597.06 m2/g under the optimized reduction time. This porous SiOx@C composite is constructed by SiOx nanoparticles uniformly dispersed in the C matrix. When tested as anode material for LIBs, it displays considerable specific capacity (1230 mAh/g at a current density of 0.1 A/g) and excellent cyclic stability with capacity fading of less than 0.5% after 200 cycles at 0.8 A/g. The dramatic volume change for the Si anode during lithium-ion (Li+) insertion and extraction can be successfully buffered because of the formation of Li2O and Li4SiO4 during initial lithiation process and carbon coating layer on the surface of SiOx. The porous structure could also mitigate the volume change and mechanical strains and shorten the Li+ diffusion path length. These characteristics improve the cyclic stability of the electrode. This low-cost and environment-friendly SiOx@C composite anode material exhibits great potential as an alternative for traditional graphite anodes.
Silicon (Si)-based materials have emerged as promising anode materials owing to the theoretical capacity as high as 4200 mAh g−1 and satisfying working potential for lithium insertion. However, ...silicon-based anode materials inevitably face the dilemmas of huge volume variation and poor electric conductivity. In this study, three-dimensional (3D) hierarchically porous SiOx/C and carbon materials have been designed and fabricated from one renewable biomass precursor (i.e., bamboo shoot hulls) through low-temperature activated treatment and mildly aluminothermic reduction. The SiOx/C anode after pre-lithiation treatment achieves an initial discharge capacity of 1332 mAh g−1 and a high capacity of 1289 mAh g−1 after 400 cycles at 200 mA g−1 as anode electrode for half lithium-ion batteries (LIBs). When employed for full LIBs, the SiOx/C exhibits a specific capacity of 142 mAh g−1 at 0.1 C with prominent cyclic stability and exceptionally low volume expansion. Moreover, hierarchically porous carbons are also prepared from the same precursor through activation of CuCl2 and further removal of SiO2, exhibiting excellent electrochemical performances for lithium/sodium ion batteries.
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•Hierarchically porous SiOx@C and carbon materials are prepared from one precursor.•Biomass wastes of bamboo shoot hulls are employed as carbon and silicon precursor.•The SiOx/C anode achieves an initial discharge capacity of 1332 mAh g−1 for LIBs.•The hierarchically porous carbons exhibit excellent performances for LIBs and SIBs.
A silicon flake/nitrogen-doped graphene-like carbon composite was prepared from organoclay via an in situ strategy, involving carbonization followed by low-temperature aluminothermic reduction. The ...pre-formed carbon sheets within the confined interlayer space of clay acted as nanotemplates for in situ synthesizing silicon flakes. As a lithium-ion battery anode, the composite exhibited excellent electrochemical properties.
Titanium-containing refractories have excellent performance, but the high cost limits their application. A series of Ti2O3–Al2O3 raw materials with different Ti2O3 contents were prepared by ...aluminothermic reduction of ilmenite, while the generated ferrotitanium alloy can be used as raw materials for special steels. Regulating the amount of aluminum added in the system regulates the degree of titanium reduction, and the formed ferrotitanium alloy can achieve separation from the oxides. With decreasing aluminum content of, the Ti2O3 content increased, and the continuous distribution of the corundum area decreased, resulting in a continuously distributed Ti2O3 area. Our results indicated that the molar ratio of aluminum to ilmenite should be higher than 1.4 to achieve slag iron separation. The reaction model for the aluminothermic reduction was established, and the formation mechanism of Al2O3 and Ti2O3 in the system was discussed.
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