Preparation Of Wood Porous Carbon Anode Materials And Performance Of Lithium/Sodium Ion Batteries

With the development and progress of society,the demand for portable electronic products with high energy and power density is increasing,among which the cathode material is one of the key factors affecting the capacity,cycle and rate performance of the battery,so it is very important to develop the cathode material with better performance and more comprehensive functions.Biomass carbon materials are rich in resources,low in price,diverse in structure and rich in functional groups,which is an excellent hard carbon precursor.Wood is interwoven with rich lignin,cellulose and hemicellulose,which can be modified and structured to prepare functional anode materials.This paper mainly takes wood as the precursor,through chemical treatment,boron atom doping and high temperature carbonization to prepare a lithium/sodium battery anode material with excellent chemical performance,safety,environmental protection and multi-function.The specific work includes the following two parts:（1）Preparation and electrochemical performance of porous wood carbon electrode.Natural wood as the precursor,through the synergistic effect of precise chemical treatment and high temperature carbonization,formed straight channels and rich closed nanopores,showing a layered pore structure,this good channel structure is conducive to electrolyte infiltration and sodium ion transport.The pore structure controlled by chemical treatment facilitates ultrafast ion transport and sodium storage and transfer.The bent graphene layers formed by high temperature carbonization accumulate into closed nanopores that gradually unfold during circulation,thus providing a higher reversible capacity in the platform region.The developed anode material can obtain A high sodium storage capacity of 439 m Ah/g at the current density of 0.1A/g,and can still maintain A high reversible capacity of 248 m Ah/g after 500 cycles.The capacity retention rate is close to 100%,and at the same time has excellent magnification performance.The rapid charge transfer kinetics and excellent rate performance of porous wood carbon anodes were proved by the combination of constant-current intermittent titration and electrochemical impedance spectroscopy.The design of wood porous carbon lays a foundation for obtaining green and efficient anode material of sodium ion battery.（2）Preparation and electrochemical performance of boron-doped wood porous carbon electrode.In order to obtain high performance lithium anode,the three-dimensional porous structure prepared by natural wood as the precursor system was used as the matrix,and the high lithium storage performance of boron was utilized to conduct heteroatomic doping.Boric acid was used as the boron source,and the boron was evenly mixed into the carbon matrix,and the boron-doped wood porous carbon was obtained by relying on the self-absorption ability of wood.The lithium storage performance was explored by controlling boron dosage and chemical treatment time.When used as the anode material of lithium-ion battery,the borondoped wood porous carbon electrode was developed to test the capacity of the half-battery at the current density of 0.1A/g,and the capacity rose to 517 m Ah/g after 500 cycles.After 500 cycles at 5A/g current density,the battery can still maintain A capacity of 128 m Ah/g,while having excellent rate performance.The assembled full battery has an initial capacity of541 m Ah/g at 0.1A/g current density.Boron-doped wood porous carbon batteries provide guidance for high current,high rate and long cycle lithium-ion batteries.