Si nanoparticles adhering to a nitrogen-rich porous carbon framework and its application as a lithium-ion battery anode material

Abstract

In this work, a novel Si/nitrogen-rich porous C composite was prepared by the simple co-assembly of gelatin, nano-CaCO 3 particles and Si nanoparticles, followed by a pyrolysis process and a subsequent acid washing treatment to remove the template. The Si nanoparticles were adhering to the nitrogen-rich porous carbon framework, which possesses good conductivity and adequate free space to accommodate the volume change of Si nanoparticles during cycling. By contrast with the bare Si nanoparticles and the conventional Si/C composite, the electrochemical performance of the as-preparedSi/nitrogen-rich porous C composite has been improved significantly. It delivers a reversible capacity of 1103 mA h g -1 after 100 cycles at a current density of 100 mA g -1 and 766 mA h g -1 at 2 A g -1 , much higher than those of commercial graphite anodes. In addition, the synthesis method can be easily scaled up and widely applied to other high-capacity anode and cathode materials systems that undergo large volume expansion.22,23

Electrochemical performance of Si anode modified with carbonized gelatin binder

“…The peaks of C 1s at 283 eV and N 1s at 398 eV can be attributed to the carbonized gelatin binder. The carbon containing nitrogen is believed to be beneficial for electrochemical performance [31]. The results of the XPS spectra are consistent with that of XRD and Raman analysis.…”

“…The Si-PV electrode displays rapid capacity decay with negligible capacity retention (below 50 mA h g À1 ) even after 4 cycles. It is demonstrated that PVDF binder is not able to adapt to the large volume change of silicon during cycling for its weak adhesion strength to silicon via van der Waals force [20,31]. According to above-mentioned Raman spectra for the Si-g-4 electrode, there remains organic substance after heat treatment, which may have a negative impact on the conductive performance and makes it show a poor cycle performance.…”

“…At a current density of 100 mA g À1 , the Si-g-5 electrode shows an initial discharge/ charge capacity of 2484/1642 mA h g À1 with a coulombic efficiency (CE) of 58.5%. The low CE is mainly caused by the following reasons: the formation of the SEI layer, which consumes a large amount of lithium, the formation of the dead Li caused by the pulverization of the electrode, which cannot participate in delithiation process, and the existence of SiO 2 layer on the surface of silicon particles [31,36,39,40].…”

“…The carbonized gelatin contains nitrogen residues, which is also benefit for lithium insertion [30e32]. In addition, some spaces could be formed among particles due to the heat treatment of the electrode, allowing for silicon expansion during cycling and facilitating the penetration of the liquid electrolyte into active material [31]. The constituent and morphology of the Si anode modified with carbonized gelatin binder are examined and the electrochemical performance is also studied in detail.…”

SiO2/Carbon Composite Microspheres with Hollow Core–Shell Structure as a High‐Stability Electrode for Lithium‐Ion Batteries

“…Compared with the SiO 2 @C, the SiO 2 /po‐C@C composite has a reversible capacity of 669.8 mA h g −1 after 100 charge and discharge cycles with a high capacity retention rate of 98.6 %, showing a significantly improved cycling performance. The reason why the SiO 2 /po‐C@C performs the excellent cycling performance is that during the insertion and extraction of lithium ions, the buffering effect of void and carbonaceous matrix not only accommodate the volume expansion and shrinkage of SiO 2 , but also prevent the pulverization of the SiO 2 /po‐C@C particles, which make the electrode materials well contact with the current collector . Moreover, the lithium silicates (Li 2 Si 2 O 5 and Li 4 SiO 4 ) also adjust the volume change of Li x Si y alloy formed in the lithiation of SiO 2 .…”