Recently, the cycling of graphite residuum generated in the machining process of isostatic graphite has aroused great interest in both academia and industry as it offers an important solution to reduce the waste of resources and environmental disruption. However, conventional method of simple backfilling of residuum suffers drawbacks of low added-value and environmental pollution owing to the high graphitization degree and low chemical activity of these graphite powders. Herein, we report a general strategy to prepare high-performance graphite block (GBB) while using recyclable graphite powder (RGP) as starting compound via constructing highly chemical active interfacial transition layers (ITLs) on the surface of RGP by impregnated pitch (IP). The ITLs decorated recycled graphite powder (RGP@SC), as reflected in FT-IR, ESR, TG-DTG and EA, contains abundant surface functional groups, free radicals, and heteroatoms which ensures the high chemical activity, thus obviously improving the self-sintering and self-adhesion properties of GBB. As a result, GBB with RGP@SC as the main aggregate display a high homogeneity and mechanical properties. The average open porosity, flexural and compressive strength are determined to 9.90%, 56.60 MPa and 123.50 MPa, respectively, which even outperforms most reported graphite blocks. Impressively, due to the absence of impregnating and multiple calcinating, the process has a short production cycle, which not only saves energy, but also is environmentally friendly. The current work displays benchmark example of the employment of RGP for synthesis of highperformance graphite block.

A new process of removing useless volatile matter from green petroleum coke (GPC) using recoverable dichloromethane (CH2Cl2) was developed to prepare self-sintering calcinated block (SCBD), which had potential application as carbon sealing materials (CSMs). Self-sintering calcinated block (SCB) was also prepared without removal unless volatile matter from GPC. Compared with SCB, SCBD had not only lower open porosity, median pore diameter and denser microstructure, but also provided superior mechanical properties, higher volume density and high yield of about 100 %. Furthermore, the flexural and compressive strength were increased by 84.57 % and 102.97 %, respectively. The correlations between the structure and properties of carbon materials were also discussed in detail. It was demonstrated that the new process studied in this work had more advantages in improving the adhesion, self-sintering, mechanical properties, and yield of the GPC than conventional direct molding process.

Understanding the evolution of the structure and related properties of pure green petroleum coke (GPC) during the sintering process is of great significance to engineering carbon graphite materials with specific functions. In this work, carbonized petroleum coke (CPC) and artificial graphite (AG) were prepared by industrial calcination and graphitization heat treatment of GPC. The pyrolysis behavior, crystal structure, microscopic morphology, particle distribution, element content, pore size distribution and electrochemical properties have been systematically analyzed and characterized. The results showed that the content of ideal graphite carbon (I g ) gradually increased as the temperature rose. The statement reported before that the interlayer spacing (d 002 ) of GPC would decrease with the increase of temperature was not suitable to the GPC in the present study. It was found that both d 002 and FWHM of GPC before the calcination temperature (1050 °C) had not obvious regularity due to the cracking, condensation and cyclization of complex small-molecule organic compounds. The particle size distribution, micropore diameter, mesopore diameter and average pore diameters of GPC decreased firstly and then increased during the sintering process. However, the total pore volume and specific surface area (SSA) of the samples not conform to the above rules, which increased first and then decreased. The anodes of sodium ion batteries (SIBs) were fabricated based on GPC, CPC and AG to confirm the conclusions obtained above. Furthermore, the Na-ion storage mechanism of the three samples was "adsorption-pore-filling".

The self-sintering process provides the possibility to prepare high-performance special carbon graphite material. However, the problem of extremely low yield caused by products cracking has not been effectively solved, which greatly limits its commercialization process. This paper creatively proposes that after removing the light component volatile substances of pure green petroleum coke (GPC) by dichloromethane (CH2Cl2). Then, carbon materials with a yield of about 100% was prepared by compression molding at 10 MPa and calcinating at 1050 degrees C for 4 h. Compared with GPC, the adhesion, self-sintering and mechanical properties of the product can also be greatly improved by this method. And its compressive and flexural strengths are increased by 89.2% and 35.2%, respectively. This exciting discovery can provide new research ideas and directions for the self-sintering process to prepare high-performance special carbon graphite material.