Study On Modification Of Silicon Anode Materials For Lithium Ion Batteries

Lithium-ion battery anode material is one of the core compoments of thelithium-ion battery. Improvement of the traditional anode materials and looking for anew anode materials become the main target of the research in this field now.Siliconanode materials is nearly10times higher than carbon anode theoretical specificcapacity and comparative with the intercalated-Li potential of carbon materials.It is avery promising lithium-ion battery anode materials with good thermal stability andchemical stability.However Si based anode materials with large volume change duringthe process of charging and discharging produces silicon grain fracture andpulverization phenomenon which lead to sudden increase to lithium-ion battery internalresistance,rapid decline in capacity and cycle performance becoming poor.Aimed at these problems this paper chooses the method of electroless plating onthe silicon powder coated on the surface of a layer of metal(nickel or copper) andchemical composite plating of silicon nickel compound thin film prepared to modifypure silicon powder and improve the cycle stability of silicon powder as the anode oflithium-ion battery.We plated a layer of metal nickel on the silicon powder surface by acidic andalkaline chemical nickel plating.Through orthogonal test analysis,it is concluded thatthe best process conditions: the loading capacity of3.0g/L, the temperature is75℃,the time for30min; Time for30min, the temperature is85℃, the loading capacity of3.0g/L. Electrochemical performance tests show that silicon nickel composite materialthat obtained by two methods as the cycle stability of the lithium ion battery cathode isimproved compared with pure silicon powder.And specific capacity attenuation arebelow5%after ten loops.We plated a layer of metal copper on silicon powder surface by using the methodof electroless copper. The orthogonal experiment analysis find out the best technologicalconditions of electroless plating of copper:the loading capacity of3.0g/L, time is2h,the temperature is65℃. Studies have shown that the best process under the condition of the preparation of silicon copper composite material for lithium ion battery anodedischarge specific capacity for the first time was941.53mAh·g-1. Increase of the cyclestability is larger compared with the pure silicon powder. The discharge specificcapacity attenuation is3.50%after the tenth cycle.Silicon nickel compound thin film was prepared on copper foil anode by themethods of the chemical composite plating.The orthogonal test analysis and find thebest process conditions of the chemical composite plating: silicon powder dosage is1.5g/L, the temperature is75℃, the plating time for30min. Silicon nickel compound thinfilm anode specific capacity(first discharge specific capacity of1817.68mAh·g-1) andcycle stability are improved.And the discharge specific capacity attenuation is only2.06%after ten times cycle test.