Triggering the Phase Conversion of GeP from Monoclinic to Cubic by Zn Substitution toward a High-Rate Ge_(1?x)Zn_xP Solid Solution Anode for Li-Ion Batteries

摘要

The monoclinic GeP with large capacity, low plateau, and high initial coulombicefficiency (ICE) has been proved to be alternative anode for Li-ionbatteries. However, the heavy use of Ge raw material with its high price,hinders its further development. Herein, the Zn atom is proposed for substitutioninto GeP and replaces part of the Ge owing to its low price, suitableplateau, and similar radius. Interestingly, a novel Ge_(1?x)Zn_xP solid solutionwith a wide range tunable region (0.143 < x < 0.6) is achieved, reducing theheavy use of Ge and cutting the GeP price down. More intriguingly, suchGe_(1?x)Zn_xP possesses a new phase, different from monoclinic GeP, which isfirst verified to be a cubic system in F-43m. Compared to semi-conductingGeP, this cubic Ge_(1?x)Zn_xP phase possesses metallic conductivity, thusenabling a better rate performance than monoclinic GeP (e.g., 881 vs283 mAh g~(?1) at 2000 mA g~(?1)), while keeping the great advantages of largecapacity, low plateau, and high ICE of GeP as well. Consequently, the assembledLiCoO_2//Ge_(1?x)Zn_xP full cell exhibits large capacity over 1000 mAh g~(?1).This unique phase control strategy by atomic substitution can be easilyextended to manipulate electrochemical behaviors of other multi-phasematerials toward advanced energy storage.