ABSTRACT
Solid-state batteries (SSBs) have emerged as a potential alternative to conventional Li-ion batteries (LIBs) since they are safer and offer higher energy density. Despite the hype, SSBs are yet to surpass their liquid counterparts in terms of electrochemical performance. This is mainly due to challenges at both the materials and cell integration levels. Various strategies have been devised to address the issue of SSBs. In this review, we have explored the role of graphene-based materials (GBM) in enhancing the electrochemical performance of SSBs. We have covered each individual component of an SSB (electrolyte, cathode, anode, and interface) and highlighted the approaches using GBMs to achieve stable and better performance. The recent literature shows that GBMs impart stability to SSBs by improving Li+ ion kinetics in the electrodes, electrolyte and at the interfaces. Furthermore, they improve the mechanical and thermal properties of the polymer and ceramic solid-state electrolytes (SSEs). Overall, the enhancements endowed by GBMs will address the challenges that are stunting the proliferation of SSBs.
ABSTRACT
Polyester nanocomposites reinforced with graphene nanoplatelets (GnPs) with two different lateral sizes are prepared by high shear mixing, followed by compression molding. The effects of the size and concentration of GnP, as well as of the processing method, on the electrical conductivity and electromagnetic interference (EMI) shielding behavior of these nanocomposites are experimentally investigated. The in-plane electrical conductivity of the nanocomposites with larger-size GnPs is approximately one order of magnitude higher than the cross-plane volume conductivity. According to the SEM images, the compression-induced alignments of GnPs is found to be responsible for this anisotropic behavior. The orientation of the small size GnPs in the composite is not influenced by the compression process as strongly, and consequently, the electrical conductivity of these nanocomposites exhibits only a slight anisotropy. The maximum EMI shielding effectiveness (SE) of 27 dB (reduction of 99.8% of the incident radiation) is achieved at 25 wt.% of the smaller-size GnP loading. Experimental results show that the EMI shielding mechanism of these composites has a strong dependency on the lateral dimension of GnPs. The non-aligned smaller-size GnPs are leveraged to obtain a relatively high absorption coefficient (≈40%). This absorption coefficient is superior to the existing single-filler bulk polymer composite with a similar thickness.
ABSTRACT
Production process was chosen in order to be readily scalable at the industrial level. The resin/graphene mixture was prepared through high shear mixing at six different weight concentrations between 0% and 10%. Samples were subsequently produced by compression molding. The electrical properties were measured both in-the-plane and across-the-plane using, respectively, a four-point probe and a two-electrode system. The two-electrode system was a dielectric spectrometer, and accordingly, the across-the-plane measurements were conducted in the frequency-domain. Mechanical measurements were conducted using conventional three-point bending and impact setups. The percolation threshold was found to be in the range of 3-5 wt.% concentration, for which the conductivity showed a 7 orders of magnitude increase. These results were quite similar to the samples containing around 50 wt.% of glass fibers. Surprisingly, the in-the-plane conductivity was found to be lower than the bulk conductivity, contrary to what was found with the same filler for thermoplastic composites prepared by melt compounding. No significant increase in mechanical properties as a function of filler loading was observed, except maybe a slight increase in the material toughness.
