Compositional Gradient Design of Ni-Rich Co-Poor Cathodes Enhanced Cyclability and Safety in High-Voltage Li-Ion Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 39973286.
- Also identified by DOI 10.1021/acsnano.5c00974.
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Abstract
Developing cost-effective high-voltage Ni-rich cathodes has reached a consensus to replace conventional ultrahigh Ni counterparts for high-energy Li-ion batteries, but more rigorous requirements are put forward for their mechanical and chemical stability. Herein, we report the design and synthesis of a full concentration gradient LiNi<sub>0.75</sub>Mn<sub>0.20</sub>Co<sub>0.05</sub>O<sub>2</sub> cathode with a Mn-rich Ni-poor surface, which has been realized by in situ forming a PO<sub>4</sub><sup>3-</sup> gradient distribution to retard the transition-metal ions' interdiffusion during the high-temperature lithiation process. This design mitigates the mechanical stress concentration at the source with high morphological integrity and refrains the lattice oxygen loss under 4.5 V high-voltage operation. After Li<sub>0.1</sub>B<sub>0.967</sub>PO<sub>4</sub> is coated, the surface parasitic reactions are further ameliorated with stable interface chemistry. The resultant Ni-rich cathodes deliver a reversible capacity as high as 212.6 mAh g<sup>-1</sup> at 2.7-4.5 V with an energy density of >800 Wh kg<sup>-1</sup><sub>cathode</sub>, almost equivalent to the state-of-the-art Ni-content 90% cathodes at 2.7-4.3 V. In commercial-grade full cells, a superior cycle life of 80.5% capacity retention is achieved at 1C within 2.7-4.5 V after 1700 cycles, exhibiting promising opportunities in compositional gradient design for Ni-rich cathodes.