Crucial role of thioacetamide for ZrO2 coating on the fragile surface of Ni-rich layered cathode in lithium ion batteries

• Published in: Journal of power sources Vol. 450; p. 227625
• Main Authors: Ho, Van-Chuong, Jeong, Seonghun, Yim, Taeeun, Mun, Junyoung
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 29.02.2020
• Subjects: Homogeneous coating; Ni-rich layered cathode; pH condition for coating; Thioacetamide; ZrO2 coating; Thioacetamide; Homogeneous coating; Ni-rich layered cathode; pH condition for coating; ZrO2 coating
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2019.227625

Thioacetamide (TA) is essentially introduced to form a ZrO2-coating in a facile method via washing with a Zr(SO4)2 aqueous solution. This method is specially applied for a Ni-rich layered oxide LiNi0.82Co0.09Mn0.09O2 (NCM82), the surface of which is chemically fragile due to unstable Ni3+ ions. Under acidic conditions due to sulfate anions, TA plays a pivotal role in preserving the fragile surface of the Ni-rich layered oxide and leads to a homogeneous coating. With the TA-supported ZrO2 coated sample, the cyclability reaches 89.4% showing a high capacity of 174.0 mAh g−1 at 0.3 C after 100 cycles, whereas the conventional ZrO2-coated sample without TA, which is generally known to be excellent for other positive electrode materials, is a low value of 64.2% with 125.7 mAh g−1 under the same condition. The TA-supported ZrO2-coated layer is notably homogeneous and has a thickness of approximately 5.75 nm. In addition, the TA-supported ZrO2-coated cathode material also displays a greatly enhanced rate capability of 116.8 mAh g−1 under a current density of 3.0 C. The structure of the ZrO2-coated cathode particle prevents unfavorable side reactions on the surface, and therefore, no micro-cracking into the grain boundary occurs after charging/discharging. The titration method demonstrates the removal of a large amount of lithium impurities from the surface of the active material. [Display omitted] •A homogeneous coating of Zr2O3 on Ni-rich layered oxide improves performance.•A facile stirring in H2O with Zr(SO4)2 and thioacetamide is developed for coating.•Thioacetamide helps to deliver a homogeneous ZrO2 coating.•Thioacetamide supports to preserve the fragile surface of Ni-rich layered oxide.