Preparation Of Camellia Oleifera-derived Biomass Carbon Anode And Its Lithium Storage Properties

Lithium-ion batteries are the most competitive green energy conversion and storage devices.Carbon materials have been favored by many researchers due to their low price,low lithium embedding potential,and good cycle stability.It is one of the most promising anode materials for lithium ion batteries.What’s more,a large number of agricultural by-products are formed in China every year.The treatment of related products is often incinerated or discarded,resulting in a large amount of wasted resources and serious environmental pollution.In recent years,many researchers have used biomass as precursor to prepare carbon materials with various morphological structures for energy storage and conversion.However,the anode materials for lithium ion batteries using biomass as precursor have some disadvantages,such as toxic agent used,the lower coulombic efficiency and the specific capacity at the first cycle.In this paper,we reported a deliberately designed two-step activation process involving hydrothermal treatment and KOH activation to convert the camellia oleifera shell as a new biomass precursor to porous nitrogen-doped carbon with modulated surface chemistry and microstructure,which improved specific capacity and coulombic efficiency of the carbon anodes.The carbon material derived from the camellia oleifera shell has also been combined with MoS₂ to improve its specific capacity further.（1）A porous carbon material with high specific surface area and multi-stage pore is prepared by combining hydrothermal treatment with KOH activation using camellia oleifera shell as a precursor.The first step of hydrothermal pretreatment accelerates the reaction of organic components in the biomass precur sor,such as dehydration,condensation and polymerization,thereby effectively introducing mesoporous structures.Subsequent activation of the KOH during the next activation process can penetrate the mesoporous structure driven by capillary forces,thereby promoting carbon-KOH interaction during subsequent KOH activation,which provides a microporous structure and produces a higher ratio.The surface area is 2210m²·g^-1,and the larger pore volume is 1.44 cm³·g^-1.As an anode electrode material for lithium ion batteries,the material exhibits an improved initial coulombic efficiency of59.6%.It has a reversible specific capacity of 1080 mAh·g^-1 at a current density of100 mA·g^-1 and is excellent in rate performance.The anode still showed good cycle stability after cycling for 150 cycles at a current density of 200 mA·g^-1 and still had a reversible specific capacity of 430 mAh·g^-1.（2）The camellia oleifera shell treated with concentrated sulfuric acid served as carbon source,ammonium molybdate and thiourea as the molybdenum source and sulfur source,respectively.The composite material of MoS ₂@C was synthesized by one-pot method.The carbon and MoS₂ were complementary to each other.First of all,MoS₂ has a relatively high theoretical specific capacity of 675 mAh·g^-1,which can make up for the shortcomings of carbon in capacity.Secondly,a porous carbon material with good conductivity is used as the substrate,which can improve the poor conductivity of MoS₂.Moreover,the spherical structure formed by the interdigitation of the MoS₂ nanosheets not only maximizes the contact area between the electrode material and the electrolyte,but also shortens the transmission path of lithium ions and increases the diffusion rate of lithium ions.As a lithium ion negati ve electrode material,the anode not only has good cycle stability,but also excellent rate performance.It has a reversible specific capacity of 804 mAh·g^-1 at a current density of 100 mA·g^-1.When the material is thrown at a current density of 1.6 A·g^-1 with a specific capacity of 280 mAh·g^-1,the current density returns to 100 mA·g^-1 and returns to 802 mAh·g^-1.The anode still has good cycle stability capacity maintained at640 mAh·g^-1 after cycling for 100 cycles at a current density of 200 mA·g^-1.