Superior Lithium Ion Storage Performance of LiCoO2 Cathode at 4.5 V Enabled by the Multiple Synergistic Effect of Nano-Silver

Abstract

LiCoO2 is still the potential first choice of cathode for lithium ion batteries due to the superior tap density of 4.1 g cm−3 and high theoretical specific capacity of 274 mAh g−1. However, the reversible capacity and cycle performance are restricted due to structural instability at high voltage (≥4.5 V). In this work, the problem will be improved by multiple synergistic effect of nano-Ag. The flake-like LiCoO2/Ag cathodes are firstly synthesized by solid state reaction and the following calcination. The structural characteristics reveal that Ag nanoparticles with ca. 10 nm are uniformly embedded into LiCoO2 particles. The initial discharge specific capacity of LiCoO2 is increased by 12% by introducing nano-Ag at 100 mA g−1 (∼0.7C) between 3.0–4.5 V, and after 100 cycles, the discharge specific capacity is enhanced by 52%. Furthermore, when the current density is increased to 2000 mA g−1, the specific capacity retention of LiCoO2/Ag researches to 62%, higher than 52% of LiCoO2. The results clearly indicate that LiCoO2/Ag cathode exhibits excellent specific capacities, enhanced cycle stability and rate performances enabled by nano-Ag through enhancing Li ions diffusion, electron transport and improving structural stability.