半限域层次孔炭三维锂负极的构筑及性能

Construction and performance of semi-confined hierarchical porous carbon three-dimensional lithium anode

金属锂负极是锂电池极具发展潜力的高能二次电池负极材料,但是锂枝晶生长、界面不稳定、循环稳定性差和体积膨胀大等问题限制了锂负极的应用。针对枝晶生长和体积膨胀的问题,本工作通过模板法构筑了一种具有较大比表面积的半限域式层次孔炭(HPC)材料,HPC电极材料的高比表面积可降低局部电流密度,丰富的孔道结构可将锂限制在其内部沉积,从而达到抑制枝晶生长和缓解体积膨胀的目的。Li‖HPC电池在电流密度为1.0 mA·cm^(-2)、沉积电量为1.0 mAh·cm^(-2)条件下可以循环超过250周次,其库仑效率保持在97.6%。采用此负极与磷酸铁锂(LiFePO_(4))正极匹配制备的Li@HPC‖LiFePO_(4)全电池,在0.5 C下循环100周次后的正极放电比容量为93.6 mAh·g^(-1),较相同条件下的Li@Cu‖LiFePO_(4)全电池(60.8 mAh·g^(-1))提升了32.8 mAh·g^(-1)。

Lithium(Li)metal is a potential anode material for high energy density batteries.However,issues such as lithium dendrite growth,interface instability,poor cycling stability and large volume expansion limit the application of lithium metal anode.Aiming at the problem of dendritic growth and volume expansion,a semi-confined hierarchical porous carbon(HPC)material with a large specific surface area was prepared by template method.The high specific area of HPC electrode can reduce the local current density of Li deposition,and the rich pore structure can restrict the Li deposition in it,thus inhibiting the dendritic growth and alleviating the volume expansion.Li‖HPC battery can cycle for more than 250 cycles at a current density of 1.0 mA/cm^(2)and a deposition capacity of 1.0 mAh/cm^(2),maintaining a Coulombic efficiency of 97.6%.Li@HPC‖lithium iron phosphate a deposition capacity of(LiFePO_(4))full cell has a specific capacity of 93.6 mAh/g after 100 cycles at 0.5 C,which is higher than that of Li@Cu‖LiFePO_(4)full cell(60.8 mAh/g)with an increase of by 32.8 mAh/g.