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Lignin, a by‐product produced during pulping and papermaking, is a phenol‐rich compound with excellent prospect to be used as a substitute for phenol in phenolic resin adhesive. Phenol‐enriched hydroxy depolymerized lignin by microwave alkali catalysis is an effective method to prepare high‐adhesive biomass composite. This study investigated the microwave digestion of lignin under different conditions of the alkali catalysis (sodium hydroxide) concentration, power, reaction time, and reaction temperature. The results show that on the condition of sodium hydroxide concentration of 0.3 mol/L, temperature of 170 °C, and time of 20 min, the highest phenolic hydroxy content obtained by depolymerization of lignin is 21.68%. SEM shows that the depolymerized lignin has no original basic constituent units and lignin‐based phenolic resin has dense uniform pine needle units. Therefore, it has a high bonding strength of 1.934 MPa. The bonding strength and phenol content obtained by the microwave depolymerization method are much higher than those of other modification methods.

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In this study, we used a carbonization method to prepare biomass-based C/ SiO 2 composites from rice husks for use in lithium ion batteries. Carbonization was carried out at different temperatures in an N 2 atmosphere and a heating rate of 5°C min À1 , and the biomass-based C/SiO 2 composites were obtained. The results showed that the lithium ion batteries maintained good cycling performance under a current density of 100 mA g À1. At the same time, they had a good performance rate at different current densities. According to thermogravimetric analysis, x-ray powder diffraction patterns, Fourier transform infrared spectroscopy, Raman spectroscopy and other data for the biomass-based C/SiO 2 composites, 700°C was the optimal carbonization temperature. At this temperature, some of the carbon was carbonized, and the sp 2 hybridized carbon in the surface functional group was weakened. Simultaneously, the connection of sp 2 hybridized carbon in C=C greatly improved the properties of the materials. According to the Brunauer-Emmett-Teller results, the biomass-based C/SiO 2 composites obtained by carbonization of rice husks had micropores, which provided active sites for insertion and extraction of Li +. This method is in line with the concept of environmental protection, as carbonization is a simple process, and rice husks are by-products of processing.

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