Rice Husk Lignin‐Derived Porous Carbon Anode Material for Lithium‐Ion Batteries

Abstract

Lignin carbonaceous is extracted from alkali-treated rice husk waste liquid through an acid precipitation process, and used as carbon source to prepare porous carbon in one-step and twostep methods with zinc chloride as activator at different temperatures. Then the obtained rice husk lignin-derived porous carbon has been used as anode materials for the lithium-ion batteries. After comparison, the material obtained by calcination at 500°C (one-step method) has displayed excellent cycle stability and high cycle specific capacity (469 mAh g À 1 after 100 cycles), much higher than the theoretical capacity of graphite. Good electrochemical performance is attributed to the unique porous structure of lignin-derived carbon material, which can shorten the diffusion distance of lithium ions and increase the contact area between electrode and electrolyte. This work provides an effective method to rationally utilize biomass waste materials, and supplies a new kind of biomass carbon anode materials for lithium ion batteries.

Spruce Hard Carbon Anodes for Lithium‐Ion Batteries

“…With increasing number of cycles, the signals shift to lower potentials (to around 0.05 V after 100 cycles) and the current increases. In former studies, the same trend was observed [21,23] and explained by the wetting of the anode and possible structural changes during charge and discharge processes. [23,29,46] In the first cathodic scan, there is a broad reduction signal at around 0.75 V, which can be associated with electrolyte decomposition and subsequent SEI formation.…”

“…At low potentials and cathodic current, lithium ions are reversibly incorporated into the hard carbon. On the anodic scan, there is a corresponding oxidation peak at around 0.2 V, suggesting reversible deintercalation of lithium ions from the hard carbon matrix [21] . With increasing number of cycles, the signals shift to lower potentials (to around 0.05 V after 100 cycles) and the current increases.…”

“…The Raman spectrum (see Figure 2b) shows the characteristic D1 and G bands at around 1344 cm À 1 and around 1580 cm À 1 , which is in good agreement with former studies on biomass-based hard carbons. [21,46] The ratio between the integrated intensity of the D1 and G bands (A D1 /A G ), which indicates the degree of graphitization, was determined to be around 3.3. Similar but slightly lower values were recently published for hard carbon derived from a commercial lignin source pyrolyzed at 1200 °C, suggesting a lower degree of graphitization of the hard carbon synthesized in our work.…”

“…[23,29,46] In the first cathodic scan, there is a broad reduction signal at around 0.75 V, which can be associated with electrolyte decomposition and subsequent SEI formation. [19,21] The long-term cycling of a spruce hard carbon-based halfcell are shown in Figure 4b. The cell shows an initial specific charge capacity higher than 250 mAh/g and a corresponding initial coulombic efficiency (CE) of approximately 65 %.…”

“…[27] Similarly, Li et al presented porous carbon anode materials derived from rice husk lignin with capacities of around 470 mAh/g after 100 cycles and a coulombic efficiency of less than 50 % in the first cycle. [21] Thus, material or process modifications are needed to make biomassderived hard carbon materials usable for lithium-ion full-cells.…”