Effect of Annealing Temperature of Ni-P/Si on its Lithiation and Delithiation Properties

Abstract

Annealed Ni–P–coated Si (Ni–P/Si) anodes for lithium-ion batteries have shown a superior cycle life with discharge capacity of 1000 mA h g−1 over 1100 cycles in some ionic-liquid electrolytes. However, the annealing temperature has yet to be optimized for Ni–P/Si electrodes. We investigated the electrochemical performance of Ni–P/Si electrode annealed at various temperatures in this study. The Ni–P/Si electrodes annealed at 800 ± 20 °C exhibited a superior cycle life with a reversible capacity of 1000 mA h g−1 over 1000 cycles, whereas the capacity of the electrodes annealed at temperatures of 750 °C and 850 °C faded at approximately 500 cycles. At 800 °C, a newly formed NiSi2 phase was theorized to significantly contribute to improving adhesion between the Ni–P coating layer and the Si particles. The Ni–P coating particles tended to aggregate at 850 °C, leading to a reduction in the coating effect, that is, a decline in their reactivity with Li+, acceleration of electrode disintegration, and a reduction in electrical conductivity. On the other hand, Ni–P/Si electrodes annealed at 850 °C exhibited a superior rate performance. The amount of available NiSi2 which ultimately contributed to higher reactivity with Li should increase.

Effect of Element Substitution on Electrochemical Performance of Silicide/Si Composite Electrodes for Lithium-Ion Batteries

“…These include reducing the size of the Si particles to prevent generation of stress, , doping Si with impurities, such as boron and phosphorous, to suppress the Si-to-Li 15 Si 4 phase transition, and/or increasing its electrical conductivity, ,− and preparing lithium silicides to decrease the relative volume change in Si during charge–discharge cycles . Other approaches involve coating Si with conductive materials to lower the electrical resistivity , or synthesizing Si-based alloys to enhance the stability of the electrode structure during cycling. − Moreover, film-forming additives or ionic liquid electrolytes have been utilized for the construction of an optimal solid–electrolyte interphase. − Lastly, composites have been prepared to improve the mechanical properties …”

Electrochemical Lithiation and Delithiation Properties of FeSi₂/Si Composite Electrodes in Ionic-Liquid Electrolytes

“…6 was obtained after pre-cycling. 47 Thus, the initial discharge capacities in Fig. 6 were close to 1000 mA h g ¹1 .…”

“…We have demonstrated that Si-based electrodes offer greater lithiation/delithiation properties in some ionic-liquid electrolytes compared to that in conventional organicliquid electrolytes in addition to the safety. 8,[41][42][43][44][45][46][47] We have investigated the effect of cation structure of N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)amide (TFSA)-based ionicliquid electrolyte on the electrochemical performance of Si-based electrodes. 48 1-((2-methoxyethoxy)methyl)-1-methylpiperidinium (PP1MEM) cation played a role reducing the interaction between Li ion and TFSA anions, and Li + transfer at the electrode-Electrochemistry electrolyte interface in PP1MEM-TFSA was remarkably improved compared with that in 1-hexyl-1-methylpiperidinium (PP16)-TFSA; the introduction of ether functional group into cation is valid to enhance the electrode property.…”

“…We used 1 mol dm ¹3 (M) lithium bis(fluorosulfonyl)amide (LiFSA) dissolved in N-methyl-Npropylpyrrolidinium bis(fluorosulfonyl)amide (Py13-FSA) or 1ethyl-3-methylimidazolium bis(fluorosulfonyl)amide (EMI-FSA) as the electrolytes because most Si-based electrodes exhibited a superior performance in them. 8,[41][42][43][44][45][46][47] We also discussed the reaction behavior of FeSi 2 /Si composite electrodes compared to that of Siand FeSi 2 -alone electrodes.…”

Impact of Low Temperatures on the Lithiation and Delithiation Properties of Si-Based Electrodes in Ionic Liquid Electrolytes

“…Precycling was conducted as follows to form a good surface film on the electrode; the Si- or P-doped Si electrode was charged from open circuit voltage (OCV) to 0.500 V vs Li + /Li at 0.1 C , maintained at 0.500 V vs Li + /Li for 12 h, and then discharged to 2.000 V vs Li + /Li at 0.1 C (1 C : 3600 mA g –1 ). 15 That is, the charge and discharge procedures of the precycling were conducted by the constant current (CC) and constant voltage (CV) mode and CC mode, respectively. Charge–discharge testing was performed at various temperatures between 303 and 233 K, whereas low-temperature testing was conducted at 263 K. The charge capacity limit was determined by controlling the limitation time to approximately 17 and 8 min for the 1000 and 500 mA h g –1 capacity limitation, respectively.…”