Macroporous Li(Ni 1/3Co 1/3Mn 1/3)O 2: A high-rate positive electrode for rechargeable lithium batteries

Abstract

Macroporous Li(Ni 1/3Co 1/3Mn 1/3)O 2 synthesized by a simple non-hydroxide route has been characterize as a high-energy and high-power positive electrode for rechargeable lithium batteries, exhibiting a discharge capacity of 195 mAh g −1 at 1 C (2244 Wh L −1) and 175 mAh g −1 at 10 C (2008 Wh L −1) and 99.99% capacity retention. Note the volumetric calculations are based on composite electrodes, not just the volume of the active material. Comparison between macroporous Li(Ni 1/3Co 1/3Mn 1/3)O 2 and the material synthesized by the conventional hydroxide method demonstrates that the latter shows a significant increase in polarization upon cycling whereas the former material does not. Cycling at 50 °C shows that the macroporous material does exhibit more polarization at elevated temperatures. Macroporous Li(Ni 1/3Co 1/3Mn 1/3)O 2 has been tested with a graphite negative electrode in a rocking-chair cell. Cycling was inferior to that with a Li metal negative electrode, but the origin of this may lie with the negative electrode. Powder X-ray diffraction also collected on macroporous Li(Ni 1/3Co 1/3Mn 1/3)O 2 after 100 cycles to 4.2 and 4.6 V, shows excellent structural stability, whereas cycling to 4.2 V induces a reduction in the Li/Ni site exchange from 4% to 2%, no significant change occurs for cycling to 4.6 V.