In an article recently published in the Journal of Physics and Chemistry of Solids, researchers discuss the impact of particle size of cotton stalks on biochar structure and anode performance for lithium-ion batteries.
Study: Effect of cotton stalk particle size on biochar structure and anode performance for lithium-ion batteries. Image Credit: Vera Larina/Shutterstock.com
Contents
Background
Lithium-ion (LIB) batteries are becoming popular for energy storage because of their high energy density, light weight, longevity, and lack of pollutants. However, due to the limited capacity of graphite and poor speed performance, the development of LIB is not possible. Significant efforts are being made to investigate next -generation carbon anode materials to improve LIB performance.
The high specific surface area and dense pore structure help improve the electrochemical performance, while the superior stability helps extend the service life of the anode. Activation and doping are two popular processes used in the manufacture of biochar to create anode materials with superior electrochemical performance. Recent researchers show that carbonization of biomass with changes in activation and doping improves the structure of biochar by altering mass and heat transport during biomass pyrolysis.
About the Study
In this study, the authors discuss the benefits of cotton stalk biochar (CSCs) as a LIB anode material. The impact of particle size on the structural and electrochemical properties of carbon derived materials was investigated.
The team used a one-step carbonization method to prepare the samples. Biochar is made from cotton stalks with large particle size used to retain the tubular structure and help in the development of pore structure and defect formation.
Researchers use agricultural waste cotton stalks as a precursor to investigate the impact of particle size on the structural and electrochemical properties of carbonization products. This simple carbonization procedure is used to make high-performance porous carbon stalk cotton.
Observations
The capacitive distribution increased with the scan rate and reached 47.57% at a scan rate of 1 mVs-1. The CSC anode has a reversible capacity of 57.62-130.33 mAhg-1 at a current density of 2 Ag-1, while graphite has a capacity of only 30.8 mAhg-1. CSC-1, 2, 3, 4, and 5 had initial specific capacities of 786.5, 872.1, 857.8, 749.85, and 646.1 mAhg-1, respectively, which rapidly decreased during reduced operation / first charge. C = O, C-OH, C – O – C, and OH had four peaks at 530.9 eV, 531.8 eV, 532.6 eV, and 533.6 eV, respectively, at higher resolution O1s.
If the particle size of the cotton stalk was smaller than 200 μm, the structural features of pyrolytic carbon changed significantly, especially the pore size below 4 nm. Carbonized cotton stalk products with particle sizes from 100 to 200 and 450 to 2000 μm reached a maximum interlayer distance of 0.388 nm and a pore volume of 0.285 cm3 g-1. Meanwhile, pyrolytic carbon made of cotton stalks with larger particle size has a superior tubular structure.
After 100 cycles on 0.1 Ag-1, biochar made from cotton stalk with particle sizes ranging from 450 to 2000 μm had the highest Li+ diffusion coefficient of 1.47×10-11 cm2 s-1 and the best electrochemical performance, with greater specificity. capacity 271.7 mAhg-1.
For the structural properties and chemical composition of biochar, the particle size of cotton stems of 200 μm is an important transformation point. When CSCs were used as anodes for LIBs, biochar cotton stalk with a diameter of 450–2000 μm had the best electrochemical performance, with a specific capacity of 271.7 mAhg-1 after 100 cycles at 0.1 Ag-1. At the same time, a high current density of 2 Ag-1 indicates a specific capacity of 115 mAhg-1.
Conclusions
In conclusion, this study elucidated that CSCs had a tubular porous structure, greater interlayer space, and higher hetero-atom doping for lithium-ion storage and transport. Cotton rods with larger particle sizes promote the formation of pore structures and retain heteroatoms during the pyrolysis process. The structure of biochar can be efficiently controlled by a variety of particle sizes of the cotton stalk, resulting in future carbon material preparation methods that are both low-energy and environmentally benign. The particle size distribution in biomass precursors has a large impact on the electrochemical performance and structure of biochar.
The authors believe that screening precursor particle size is a promising strategy for improving electrochemical performance, and it also presents ideas for other energy storage devices, thanks to a large range of precursors and cheap and convenient manufacturing procedures.
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Source
Wang, Y., Chang, H., Ma, T., et al. Influence of cotton stalk particle size on biochar structure and anode performance for lithium-ion batteries. Journal of Solid Physics and Chemistry 110845 (2022). https://www.sciencedirect.com/science/article/abs/pii/S0022369722002736
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