| It’s reported that the world need to double the energy by 2050. In such situation, novel nanomaterial has opened up new frontiers in materials science to meet this challenge. In particularly, carbon nanomaterials have exhibited efficient energy conversion and storage. Comparing to conventional energy materials, carbon nanomaterials possess unique morphological, electrical, optical, and mechanical properties useful for enhancing the energy-conversion and storage performances. Porous carbon materials have been applied in gas separation, water purification, catalytic supports, and electrodes for lithium-ion batteries, super capacitors and fuel cells, because of its merits in cost, specific surface area, electrical conductivity and chemical stability. When using as anode of lithium-ion batteries, porous carbon materials possess not only higher specific capacity than graphite, but also a better cyclical stability.This paper mainly focuses on novel method to prepare porous carbon materials, and applying them in lithium-ion batteries anode, discussing their electrochemical properties. The paper contains two research topics, the one proposed a novel method—air expansion to fabricate carbonaceous aerogels with 3D porous structure; Another one prepared a porous carbon material with ultrahigh specific surface area and ultrahigh lithium-ion storage, based on KOH activation using dopamine as carbon precursor.Air-expansion induced carbonaceous aerogels from biomass materials are detailed in chapter 3. Traditional methods for the preparation of carbon aerogels, such as sol-gel method, hydrothermal method, freeze-drying method and direct carbonization of biomass materials, have been more and more limited for applications due to their high cost, complex process and the accompanying volume shrinkage in the preparation process. In this paper, we developed a novel air-expansion method for the preparation of porous carbonaceous aerogels with hierarchically macroporous, mesoporous and microporous structures from rice. The main advantage of air-expansion method is large-scale preparation, low cost, simple technique and most important keeping the initial shape/structure and avoiding the shrinkage of carbon aerogels owing to air-expansion process of rice generating many macroporous structures for supporting aerogel framework. When used as an anode for lithium ion batteries, rice-based carbonaceous aerogel exhibits a superior specific capacity and possesses a good rate capability. This study gives a better insight for the preparation of carbonaceous aerogel from other grains as well as it potential applications in lithium-ion batteries.In chapter 4, we demonstrated a porous carbon with ultrahigh specific surface area and excellent lithium-ion storage using dopamine as nitrogen-containing carbon precursor and KOH as activated agent. The dopamine microspheres possess good thermal stability, allowing a higher activated temperature to produce more micro- and meso-pores. As a result, the as-prepared porous carbon materials possess a specific surface area as high as 4888 m2/g, when using as anode of lithium-ion batteries, it showed a discharge specific capacity of 8263 mAh/g in first cycle, and remain 2967 mAh/g during charge at a current density of 0.1 A/g. At a current density of 1 A/g, it can still retain 1208 mAh/g after 600 cycles. As far as we know, such a porous carbon materials with ultrahigh specific surface area and lithium-ion storage have never been reported before. |
