Understanding Electrochemical Performance Enhancement with Quaternary NCMA Cathode Materials

Abstract

Ni-rich cathode materials show promise for use in lithium-ion batteries. However, a significant obstacle to their widespread adoption is the structural damage caused by microcracks. This research paper presents the synthesis of Ni-rich cathode materials, including LiNi0.8Co0.1Mn0.1O2 (referred to as NCM) and Li­(Ni0.8Co0.1Mn0.1)0.98Al0.02O2 (referred to as NCMA), achieved through the high-temperature solid-phase method. Electrochemical (EC) testing results reveal the impressive EC performance of NCMA. NCMA exhibited a discharge capacity of 141.6 mAh g–1 and maintained a cycle retention rate of up to 74.92% after 300 cycles at a 1 C rate. In contrast, the NCM had a discharge capacity of 109.7 mAh g–1 and a cycle retention rate of 61.22%. Atomic force microscopy showed that the Derjaguin−Muller−Toporov (DMT) modulus value of NCMA exceeded that of NCM, signifying a greater mechanical strength of NCMA. Density functional theory calculations demonstrated that the addition of aluminum during the delithiation process led to the mitigation of anisotropic lattice changes and the stabilization of the NCMA structure. This improvement was attributed to the relatively stronger Al–O bonds compared to the Ni­(Co, Mn)–O bonds, which reduced the formation of microcracks by enhancing NCMA’s mechanical strength.

LiNbO3 Coating and F– Doping Stabilize the Crystal Structure and Ameliorate the Interface of LiNi0.88Co0.06Mn0.03Al0.03O2 to Improve the Electrochemical Properties and Safety Capability

“…Since the discovery of Ni-rich layered cathode material Li­[Ni x Co y Mn z Al 1 – x – y – z ]­O 2 (NCMA, x > 0.8) from the combination of NCM and NCA oxides, it has gained much attention and abundant research continuously for the superior structural stability and the large discharging capacity when applied in lithium-ion batteries (LIBs) used for EV and HEV and is generally regarded as the next-generation hopeful cathode material for high energy density batteries. − Nonetheless, the high nickel content in the NCMA oxides brings about some significant issues to hinder the extensive application, including the serious cation mixing between Li + and Ni 2+ to lower the diffusion rate of Li + , the unwanted surface residual alkali (LiOH and Li 2 CO 3 ) leading to manufacturing problems, and cacoethic side effect resulting from the intense oxidation of Ni 4+ . − Moreover, the release of highly reactive oxygen species from Ni-rich layered materials during charging–discharging could oxidize electrolytes and anodes, leading to the exacerbating of the thermal runaway. , This issue would further aggravate the safety failure risk and release more energy and heat during the thermal runaway process, which is regarded as the chief safety concern for the Ni-rich oxides used in LIBs. The above deficiencies obstruct the utilization of Ni-rich quaternary cathodes in a broad range of applications.…”