The Preparation And The Performance Of Hollow Sn-Cu Particles Anode Materials For Lithium-ion Battery

With high energy density, long cycle life and safety, lithium-ion batteries arewidely used in a variety of electronic equipment. Sn-based materials are a kind ofpromising anode materials for lithium-ion batteries because of its high theoreticalcapacity and safety. Nevertheless, due to the volume expansion of about100%-300%during the lithium insertion/extraction process, the poor cycling stability limits the useof Sn-based materials. So it is extremely important to relieve volume change duringcharge and discharge process.To improve the cycle stability, we did research in two aspects:1, preparation ofSn nanoparticles, Nanoscale can reduce the diffusion distance and accommodate largemechanical strain associated with volume expansion.2, Hollow Sn-Cu particles wereachieved by galvanic replacement. Cu elements and hollow structure can alleviate thevolume expansion, improving the cycle stability. The structure and morphology ofprepared materials were detected by SEM, TEM and XRD. We assembled a half-celland tested the cycle stability.1. Sn nanoparticles were prepared by chemical reduction. The reaction coursecan be easily controlled and have excellent repeatability. Different morphology wasachieved by changing the type and amount of the modifiers. The results showed thatthe average diameter of Sn nanoparticles was31nm in sulfuric acid solution usingPVP as the modifier. It delivers a discharge capacity of1389mAhg^-1and a reversiblecapacity of1136mAhg^-1in the frst discharge/charge cycle with a coulombiceffciencyof81.79%. The capacitydecreased slowlyand dropped below100mAhg^-1.The Sn nanoparticles electrode showed improved cycling performance. But the cyclestability is not good enough and need more improvement.2. Hollow Sn-Cu particles were achieved by galvanic replacement which issimple, cost-effective. The average diameter of hollow Sn-Cu particles was241nm.Hollow Sn-Cu particles exhibited a discharge capacity of1211mAhg^-1and areversible capacity of1000mAhg^-1in the frst discharge/charge cycle, correspondingto a coulombic effciency of82.58%. The capacity remained at450mAhg^-1after30cycles. The cycle stability were increased greatly. This pave the way for highperformance lithium-ion batteries.