Surface Modification Improves Spinel LiCoO2 Li-Ion Battery Cathode Materials Grown by Low Temperature Solvothermal Flow Reaction

Abstract

Methods that provide routes to LiCoO2 growth with lower energy requirements from recycled battery cathode ashes are important for sustainable Li-ion battery technology . Here, a low temperature route to a stable, coated spinel-phase LT-LCO material with secondary Co3O4 phase can be achieved at 300 °C directly from the layered double hydroxide [Li2(ox)2][Co5(OH)8] product of solvothermally synthesized LiOH and CoCl2. The low-temperature LiCoO2 materials (known as LT-LCO) consist of spinel-phase LCO and secondary Co3O4 phase. As a cathode in lithium batteries, we used a solution-based method of coating with an ionic conductor LiAlO2 with AlF3 to mitigate sluggish reversible lithiation kinetics and the poor cycling and rate performance of as-synthesized spinel LT-LCO. The coating modification promotes reversible lithium ion transfer and stabilizes the spinel structure. The modified LT-LCO cathode has significantly better overall capacity and rate performance, with a capacity retention of ∼80 mAh g−1 after 150 cycles (factoring the LT-LCO and Co3O4 mass). The initial first cycle coulombic efficiency significantly improves to >95%. The data show that even spinel phase LCO grown by this solvothermal route cycles stably with a useful specific capacity and rate response in the voltage range 2.0-4.2 V.