Enhanced cycle capacity retention of plasma-sprayed SiO_xnanocomposite powders for negative electrode of lithium ion batteries

Abstract

Core-shell SiO x nanocomposite powders have been produced in a single continuous plasma spray process. The addition of CH 4 at appropriate amounts during plasma spraying of SiO was found to be quite effective in promoting the reduction of SiO and thus increasing the crystalline Si amount after the disproportionation reaction. The half-coin cell assembled using these powders for the negative electrode has exhibited a stable capacity higher than 1000 mAh/g with the coulombic efficiency of around 99.3%, both of which are higher values than those of the cell with raw SiO. Electrochemical analysis has revealed that the resistance at the SiO x particle surface decreases potentially with Li 2 O formation from the beginning of the first lithiation. The decrease in the resistance is further enhanced by the addition of CH 4 , although more volume change is expected because of the increased crystalline Si phase content. As a result, the core-shell SiO nanocomposite produced by plasma spraying with CH 4 becomes advantageous in attaining high capacity and high retention efficiency simultaneously.

High throughput production of nanocomposite SiOxpowders by plasma spray physical vapor deposition for negative electrode of lithium ion batteries

“…These results suggest that although the individual nc-Si particle with no SiO x shell is less stable even after the structural change from crystalline into amorphous, if nc-Si is surrounded by the SiO x to form a core–shell structure, they are anticipated to be reasonably stable in maintaining their structure and thus retaining capacity. This is probably because the Li–O alloy phase acts as buffer as reported [6], and also because the a-SiO x shell changes into Si–Li–O during lithiation and provides an electrically conducting web connecting directly the nc-Si particles [27]. …”

Gas‐Phase Plasma Synthesis of Free‐Standing Silicon Nanoparticles for Future Energy Applications

“…The extreme high power, and the ability of feeding solid precursor through the thermal plasma zone results in very high throughputs of more than 300 g of Si‐NPs per hour, which is among the highest Si‐NP processing throughput reported using plasmas . Apart from Si‐NPs, synthesis of various nanoparticles in thermal plasmas such as SiO 2 , SiO x , SiO x –Ti, SiC, TaC, Al 2 O 3 , TiO 2 , and W‐bronze have been reported.…”

“…In an electrochemical analysis study, Kambara et al investigated the electrochemical impedance characteristics of Si/SiO x core/shell composite nanoparticles with an addition of CH 4 gas (C/Si molar ratio of 0.25) during synthesis. The cells with stable capacities of 1000 mAh g −1 (for 50 cycles) were analyzed by means of electrochemical impedance spectroscopy (EIS).…”

High rate synthesis of graphene-encapsulated silicon nanoparticles using pulse-modulated induction thermal plasmas with intermittent feedstock feeding

“…[16][17][18][19][20][21][22][23][24] Such the ICTP method has also actively been tested for synthesizing Si-based nanomaterials for anode material in LIB, including carbon-coated Si nanoparticles, Si/C nanocomposites, etc. [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] On the other hand, we have developed a novel technique of the PMITP+TCFF method for high rate production of nanoparticles. [41][42][43][44][45][46][47][48] The pulse-modulated induction thermal plasma (PMITP) is the PMITP, which is sustained by amplitude-modulated coil current.…”