The poor structural stability and cycling coulombic efficiency(CE)of silicon–carbon composites largely limit their commercial application.In this report,a compact silicon–carbon composite with an embedded structure(...The poor structural stability and cycling coulombic efficiency(CE)of silicon–carbon composites largely limit their commercial application.In this report,a compact silicon–carbon composite with an embedded structure(Si@C)is fabricated by a facile and scalable approach.Coal tar pitch is carbonized to obtain amorphous carbon.Nano-silicon is uniformly embedded in an amorphous carbon matrix which acts as a three-dimensional conductive network.Meanwhile,no obvious interface can be observed between amorphous carbon and nano-silicon.As the anode material,the Si@C composite displays a high specific capacity of 1314.6 mA h g^(-1)and an average CE of 99.66%from the 10th to 100th cycle.The amorphous carbon can restrain the volume variation of nano-silicon,and the structure of the Si@C composite can remain intact during cycling.The Si@C-G composite is designed,which comprises the Si@C composite and commercial graphite anode materials,to further improve the CE and make the Si@C composite suitable for lithium-ion batteries with different energy densities.The capacity of the Si@C-G composite is controlled to 669.5 mA h g^(-1);the composite shows an initial CE of 83.76%,a high average CE of 99.88%and a capacity retention of 80.10%over 250 cycles.Besides,the full cell of Si@C-G exhibits the excellent electrochemical performance.Therefore,this Si@C composite can be developed into anode materials with high CE for lithium-ion batteries.展开更多
基金supported by the National Key R&D Program of China(No.2016YFB0100400)the National Natural Science Foundation of China(No.51604032)the Talent Plan Project of Beijing(No.2017000097607G094,2018000097607G378).
文摘The poor structural stability and cycling coulombic efficiency(CE)of silicon–carbon composites largely limit their commercial application.In this report,a compact silicon–carbon composite with an embedded structure(Si@C)is fabricated by a facile and scalable approach.Coal tar pitch is carbonized to obtain amorphous carbon.Nano-silicon is uniformly embedded in an amorphous carbon matrix which acts as a three-dimensional conductive network.Meanwhile,no obvious interface can be observed between amorphous carbon and nano-silicon.As the anode material,the Si@C composite displays a high specific capacity of 1314.6 mA h g^(-1)and an average CE of 99.66%from the 10th to 100th cycle.The amorphous carbon can restrain the volume variation of nano-silicon,and the structure of the Si@C composite can remain intact during cycling.The Si@C-G composite is designed,which comprises the Si@C composite and commercial graphite anode materials,to further improve the CE and make the Si@C composite suitable for lithium-ion batteries with different energy densities.The capacity of the Si@C-G composite is controlled to 669.5 mA h g^(-1);the composite shows an initial CE of 83.76%,a high average CE of 99.88%and a capacity retention of 80.10%over 250 cycles.Besides,the full cell of Si@C-G exhibits the excellent electrochemical performance.Therefore,this Si@C composite can be developed into anode materials with high CE for lithium-ion batteries.
