Soft carbon composites

The morphology of the agglomerates has been problematic, although some forms of network-like structures have been assumed on the basis of percolation behavior of conductivity and some mechanical properties, e.g., the Payne effect. These network stmctures are assumed to be determining the electrical and mechanical properties of the carbon-black-filled vulcanizates. In tire industries also, it plays an important role for the macroscopic properties of soft nano-composites, e.g., tear. 

Thus, the electrochemical properties of the individual carbon materials are not so high as to enable their commercial usage in Li-ion batteries. In order to improve the performance, we started making composite materials from two individual carbon ingredients. Figure 1 shows a typical result of electrochemical tests of an electrode made of a blend of graphite and soft carbon treated at 1100°C (Cl 100) in comparison with the discharge curves of the individual constituents. 

Regarding their mechanical properties carbon composites can thus be classified as rigid composites [18,19] or soft composites—the carbon pastes - [20]. The composites are also classified by the arrangement of their... 

On the other hand, sodium intercalates in the soft carbons with increasing facility as the maximal temperature of treatment of carbon (HTT) is lowered e.g., a petroleum coke at 1250°C leads to a third stage NaC24, and a coke heated at 800°C can lead to a first stage with a composition near NaCg. Hard carbons are also able to accept 20% of their weight or more of sodium, partly by intercalation, and more by adsorption and condensation in the porosity. ... 

Ohta, T., I. T. Kim, M. Egashira, N. Yoshimoto, and M. Morita. 2012. Effects of electrolyte composition on the electrochemical activation of alkali-treated soft carbon as an electric double-layer capacitor electrode. Journal of Power Sources 198 408-415. 

Many applications currently exist for carbon composite and polymer materials. Ion implantation is a technique that can result in a combination of the best properties of polymers and of carbon composites. Polymers, used for stmctural and packaging applications, have disadvantages, which usually include softness, low thermal stability, high chemical permeability, and low electrical conductivity. The lack of electrical conduction can lead to problems such as triboelectrification and electrostatic charging. The electrical conduction properties of polymers can be controlled by ion implantation. Ion implantation can make any polymer surface electrically conductive, chemically impermeable, and mechanically hard. Some appli-... 

Figure 19 represents the depth-dependent elemental composition of the SEI formed in LiPF electrolyte on the soft carbon (top figure, 19a) and on the hard... 

The similarity of the SEI content in the two electrolytes stands out if one looks at the composition of surface SEI formed on soft carbon in both electrolytes (Figures 20a and 23a). The atomic concentration of LiF is in range of 35-38%, polymers 18-21%, C-O-containing compounds 20-24%. 

The nature of the SEI, which is dependent upon the nature of the electrolyte and the nature and composition of the solvent components is a crucial issue governing the performance of both hard and soft carbon anode materials as discussed above. The determination of individual processes which limit the low temperature curabilities of carbon-based anodes is complex, but experiments have been designed to identify, at least qualitatively, individual mechanisms relating to dissolution or growth of the SEI, Li(m) deposition, or to slow electrode kinetics and/or slow solid-state diffusion. In "half-cells" of the type... 

---