The layered Ni-rich NiCoMn (NCM)-based cathode active material Li[Ni_xCo_(1−x)/2Mn_(1−x)/2]O₂ (x ≥ 0.6) has the advantages of high energy density and price competitiveness over an LiCoO₂-based material. Additionally, NCM is beneficial in terms of its increasing reversible discharge capacity with the increase in Ni content; however, stable electrochemical performance has not been readily achieved because of the cation mixing that occurs during its synthesis. In this study, various layer-structured Li_1.0[Ni_0.8Co_0.1Mn_0.1]O₂ materials were synthesized, and their electrochemical performances were investigated. A NiCoMnCO₃ precursor, prepared using carbonate co-precipitation with Li₂CO₃ as the lithium source and having a sintering temperature of 850 °C, sintering time of 25 h, and metal to Li molar ratio of 1.00–1.05 were found to be the optimal parameters/conditions for the preparation of Li_1.0[Ni_0.8Co_0.1Mn_0.1]O₂. The material exhibited a discharge capacity of 160 mAhg⁻¹ and capacity recovery rate of 95.56% (from a 5.0–0.1 C-rate).

This study introduces NiWO₄ as a main photocatalyst, where the Ni component promotes methanation to generate a WO₃-based catalyst, as a new type of catalyst that promotes the photoreduction of carbon dioxide by slowing the recombination of electrons and holes. The bandgap of NiWO₄ is 2.74 eV, which was expected to improve the initial activity for the photoreduction of carbon dioxide. However, fast recombination between the holes and electrons was also expected. To overcome this problem, attempts were made to induce structural defects by partially replacing the Ni²⁺ ions in NiWO₄ with Li⁺. The resulting CO₂ conversion reaction was greatly enhanced with the Ni_1-xLi_2xWO₄ catalysts containing Li⁺, compared to that of the pure NiWO₄ catalysts. Notably, the total amount of CO and CH₄ produced with the Ni_0.8Li_0.4WO₄ catalyst was 411.6 nmol g⁻¹. It is believed that the insertion of Li⁺ ions into the NiWO₄ skeleton results in lattice defects due to charge and structural imbalance, which play a role in the capture of CO₂ gas or excited electrons, thereby inhibiting recombination between the electrons and holes in the Ni_1-xLi_2xWO₄ particles.