Boosting the Electrochemical Performance of Li- and Mn-Rich Cathodes by a Three-in-One Strategy

There are plenty of issues need to be solved before the practical application of Li- and Mn-rich cathodes, including the detrimental voltage decay and mediocre rate capability, etc. Element doping can effectively solve the above problems, but cause the loss of capacity. The introduction of appropriate defects can compensate the capacity loss; however, it will lead to structural mismatch and stress accumulation. Herein, a three-in-one method that combines cation-polyanion co-doping, defect construction, and stress engineering is proposed. The co-doped Na+/SO42- can stabilize the layer framework and enhance the capacity and voltage stability. The induced defects would activate more reaction sites and promote the electrochemical performance. Meanwhile, the unique alternately distributed defect bands and crystal bands structure can alleviate the stress accumulation caused by changes of cell parameters upon cycling. Consequently, the modified sample retains a capacity of 273 mAh g(-1) with a high-capacity retention of 94.1% after 100 cycles at 0.2 C, and 152 mAh g(-1) after 1000 cycles at 2 C, the corresponding voltage attenuation is less than 0.907 mV per cycle.

Automated summary

This study proposes a three-in-one method combining cation-polyanion co-doping, defect construction, and stress engineering to address the capacity loss, structural mismatch, and stress accumulation issues in Li- and Mn-rich cathodes. The co-doped Na+/SO42- stabilizes the framework, enhances capacity and voltage stability, while induced defects activate more reaction sites and improve electrochemical performance. The unique defect bands and crystal bands structure alleviate stress accumulation, resulting in high-capacity retention and low voltage attenuation after cycling.