Achieving Thermodynamic Stability of Single-Crystal Co-Free Ni-Rich Cathode Material for High Voltage Lithium-Ion Batteries

摘要

Ni-rich layered cathode materials are progressively considered as thestandard configuration of high-energy electric vehicles by virtues of theirhigh capacity and eliminated “range anxiety.” However, the poor cyclicstability and severe cobalt supply crisis would restrain their wide commercialapplicability. Here, a cost-effective single-crystal Co-free Ni-richcathode material LiNi_(0.8)Mn_(0.18)Fe_(0.02)O_2 (NMF), which outperforms widelycommercial polycrystalline LiNi0.83Co0.11Mn0.06O2 (MNCM) and singlecrystalLiNi_(0.83)Co_(0.11)Mn_(0.06)O_2 (SNCM) is reported. Surprisingly, NMF cancompensate for the reversible capacity loss under the designed conditionsof high-temperature and elevated-voltage, achieving a competitive energydensity compared with conventional MNCM or SNCM. Combining operandocharacterizations and density functional theory calculation, it is revealed thatNMF cathode with improved dynamic structure evolution largely alleviatesthe mechanical strain issue commonly found in Ni-rich cathode, which canreduce the formation of intragranular cracks and improve the safety performance.Consequently, this new Co-free NMF cathode can achieve a perfectequilibrium between material cost and electrochemical performance, whichnot only reduces the production cost by >15, but also demonstrates excellentthermal stability and cycling performance..