Double the energy storage of hard carbon anode for Li-ion batteries via a simple blending strategy

Blending two materials together to improve electrode performance has been proven an effective and practical strategy in the battery industry. Herein, we fabricate a novel n-HC/GeP 5 composite that doubles the energy density over hard carbon (HC) without sacrificing cycle stability and rate performance. The GeP 5 , with high capacity (2289 mAh g −1 ), ultra-high conductivity (2.4*10 6  S m −1 ) and high initial coulombic efficiency (ICE > 90%), enables it serve as an effective additive to HC at a low weight percent. By introducing 20% wt GeP 5 by mass ratio into HC, the obtained n-HC/GeP 5 -20%wt composite improves the reversible capacity from 400 mAh g −1 to 898 mAh g −1 , and improves ICE from 74% to 85%. In addition, the rate capability of n-HC/GeP 5 , with 516 mAh g −1 and 64% retention comparing 1C–8C, is much better than that of pure HC (273 mAh g −1 , 54% retention). Consequently, when tested at 1C and 8C for 550 cycles, large reversible capacity of 575 mAh g −1 and 400 mAh g −1 respectively can still be obtained for this n-HC/GeP 5 -20% hybrid, revealing its great potential to be used in commercial battery products.