Improved Electrochemical Performance and Thermal Stability of Ni-Rich LiNi_0.90Co_0.05Mn_0.05O₂ Cathode Material by WO₃ Coating

To increase the stability of Ni-rich LiNi<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.90</inf>Co<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.05</inf>Mn<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.05</inf>O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>(NCM90), WO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> was used as a surface coating material at concentrations of 0.2, 0.5, and 0.8 wt%. It is discovered that WO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> can form a thin and uniform coating on the surface of NCM90, effectively isolating interfacial parasitic reactions and promoting Li<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup>conduction. Electrochemical studies show that a 0.2 wt% WO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> coating may significantly lower the impedance, raise the specific discharge capacity by 21.12 mAh/g, and improve capacity retention by 4.88% after 200 cycles. DSC results demonstrate that the heat release of NCM90 is decreased by 46.77 J/g due to the 0.2 wt% WO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> coating, indicating increased thermal safety of material. These findings suggest that WO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> coating can effectively improve the electrochemical and thermal stability of Ni-rich cathode, which shows its application potential in the field of lithium-ion batteries.