Silicon nanowires as negative electrode for lithium-ion microbatteries

Abstract

International audienceThe increasingly demand on secondary batteries with higher specific energy densities requires the replace- ment of the actual electrode materials. With a very high theoretical capacity (4200 mAh g−1 ) at low voltage, silicon is presented as a very interesting potential candidate as negative electrode for lithium-ion micro- batteries. For the first time, the electrochemical lithium alloying/de-alloying process is proven to occur, respectively, at 0.15 V/0.45 V vs. Li+ /Li with Si nanowires (SiNWs, 200-300 nm in diameter) synthesized by chemical vapour deposition. This new three-dimensional architecture material is well suited to accom- modate the expected large volume expansion due to the reversible formation of Li-Si alloys. At present, stable capacity over ten to twenty cycles is demonstrated. The storage capacity is shown to increase with the growth temperature by a factor 3 as the temperature varies from 525 to 575 ◦ C. These results, showing an attractive working potential and large storage capacities, open up a new promising field of research

Evaluating the performance of nanostructured materials as lithium-ion battery electrodes

“…The arrays of Si nanowires displayed a capacity of >2100 mA h g -1 at C rate (1 C = 4212 mA h g -1 , corresponding to a complete discharge in 1 h), and ~3500 mA h g -1 over 20 cycles at the C/5 rate, with no appreciable decline in capacity or apparent pulverisation of the nanowire structure [22]. Earlier studies of Si nanowires prepared by a VLS mechanism displayed stable cycling over 10-20 cycles [23]. Kang et al [24], prepared single crystalline Si nanowires on stainless steel substrates by a chemical vapour deposition (CVD) method, which approached a near theoretical limit (4212 mA h g -1 ) in the first discharge of ~4000 mA h g -1 .…”

Li15Si4Formation in Silicon Thin Film Negative Electrodes

“…1 Acoustic emission studies and imaging techniques have indicated that this phase transition can result in high internal stresses, leading to particle fracture and cell fade. 2 To overcome the issues associated with Li 15 Si 4 phase formation and volume expansion during cycling, researchers have demonstrated high cycle life in Li cells by using Si in the form of nanoparticles, 3,4 nanowires, 5,6 nanopillars, 7,8 thin films, 9,10 and in alloys with inactive or active phases. 11,12 These studies have reported various threshold sizes for nanoparticles (150 nm), 3,4 nanowires (300 nm), 13 and amorphous thin films (2.5 μm), 14 below which Li 15 Si 4 formation does not occur.…”

Alloy-Based Anode Materials

“…The galvanostatic charge-discharge curves obtained for such thin films of Au exhibit two voltage plateaus corresponding to the Li alloying process at 0.2 and 0.1 V, whereas Li removal from the alloy occurs in two steps at 0.18 and 0.4 V [152,153]. Mesoporous Au films show a better cycling stability than their compact thin film counterparts, with *16 % (at 80 mAh/g) of the original capacity retained after 30 charge-discharge cycles [154].…”

“…Although there are few literature papers on the electrochemical alloying of Au with Li at RT, Au thin films have been shown to accommodate Li in the 0.02-0.5 V potential range with a poor reversibility [152,153]. The galvanostatic charge-discharge curves obtained for such thin films of Au exhibit two voltage plateaus corresponding to the Li alloying process at 0.2 and 0.1 V, whereas Li removal from the alloy occurs in two steps at 0.18 and 0.4 V [152,153].…”