Preparation And Performance Of Nitrogen-doped Carbon/Tin Anodes Based On Dynamic Covalent Bond

As the new green energy,lithium ion batteries have become the first choice of portable electronic devices and gradually been widely used in the field of power energy.However,the existed system of lithium ion batteries represented by carbon anode materials can not meet the requirements of long life,high capacity and rapid charge-discharge.And tin-based materials have become one of the most promising anodes for lithium ion batteries by the high theoretical capacity and mature modification method.Nevertheless,their volume expansion during charge-discharge process becomes the biggest obstacle to further application and development.This paper started with nitrogen doping and used nitrogen-rich reagents as raw materials to prepare BNP as precursors,which were calcined under protective atmosphere and nitrogen-doped carbon?NC?particles were got.The morphology,structure and composition of NC were analyzed and confirmed as solid spheres,and electrochemical tests show that NC electrode delivers a reversible capacity of 350 mA h g^-1at a current density of 0.2 A g^-1after 250 cycles,demonstrating the important role of nitrogen doping in improving the electrochemical performance of carbon materials.Based on the results above,this paper synthesized metal-organic nanoparticles(Sn⁴⁺-MOP)via using dynamic covalent bond of BNP,which were calcined to uniformly disperse tin nanoparticles in nitrogen-doped hollow carbon spheres and nitrogen-doped hollow carbon/tin?NHC/Sn?particles were finally got,and the electrochemical measurement tests show the NHC/Sn electrode has superior cycling stability and rate capability:it can maintain a reversible capacity of 606 mAh g^-1 at a constant current density of 0.2 A g^-1 after 250 cycles and a reversible capacity of 221m Ah g^-1even at a much higher current density of 10 A g^-1.The NHC/Sn particles integrated the advantages of nanosizing of tin,carbon coating,hollow structure and nitrogen doping,which could address all the problems of tin-based anodes at once.Therefore,the study of nitrogen-doped C/Sn composites has important significance to improve the electrochemical performance and cycling life.