Non-Eutectic-Salt Reaction Route towards Morphological and Structural Rearrangement of Li-Rich Layered Oxides for High-Volumetric Li-Ion Batteries

When a weak mechanical strength of particles on cathode materials occurs, the prepared electrode fails to achieve a high compaction density with undegraded performances, which causes a low volumetric energy density in batteries. Herein, we propose a LiOH-Li2CO3 non-eutectic-salt reaction route to achieve the particles with high densification and superior mechanical stability in Li-rich layered oxides. Temperature-dependent in situ synchrotron X-ray diffraction and advanced scanning/transmission electron microscopy help reveal the process of the structural and morphological rearrangement on this non-eutectic-salt reaction. In the non-eutectic-salt system, the pinning effect caused by the minority second-phase particles can restrict an excessive particle growth and increase a grain densification to improve the mechanical properties of the particles. In contrast to conventional reaction route, the compaction density of the as-fabricated electrode can reach 2.8 g cm−3 with very few particles cracking. Consequently, the target material delivers an initial discharge capacity of 273 mAh g-1 and the columbic efficiency over 90%, as well as a capacity retention of 87.2% after 150 cycles at C/2. A 2.1 Ah multilayer pouch cell with graphite anode shows a capacity retention of 78.6% with current of 760 mA after 300 cycles.