LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathode material is prized in the electric vehicles (EVs) industry for its high capacity and voltage during operation. However, the high residual alkali content and inferior ionic conductivity of Ni‑rich cathode materials are the intractable obstacles to the large-scale commercial application for a long time. Herein, a feasible Nb 2 O 5 coating strategy is proposed to eliminate residual alkali along with constructing high Li + conductive coating layer on NCM811 cathode materials surface. Impressively, 0.3% Nb 2 O 5 ‑coated NCM811 cathode exhibits superior rate capability (146.4 mA h g −1 @400 mA g −1 ) and remarkable rate cyclic stability (188.5 mA h g −1 after 100 cycles with capacity retention of 94.8%). On the one hand, a small quantity of Nb 2 O 5 coating on NCM811 surface can react with surface residual alkali to promote the transformation of low electronic conductivity surface residual alkali into the Li + conductor of LiNbO 3 coating layer, enhancing Li + de-intercalation kinetics and rate performance. On the other hand, excessive Nb 2 O 5 coating may introduce Nb 5+ into the lattice of NCM811, acting as pivotal components within the Li + layer, which effectively suppresses the H2 ↔ H3 phase transition, contributing to long-term cyclic stability. This work paves a new path for the rational design and facile coating of Ni-rich oxide cathode materials with reinforced structure stability and boosted rate capability in high‑energy‑density lithium-ion batteries.
Reducing defect density and hindering charge recombination in perovskite film and at perovskite/semiconductor interface are crucial to perovskite solar cells (PSCs) performance. In this paper, hydrothermally prepared TiO 2 nanorod arrays (TNRAs) were coated with Nb 2 O 5 layer using a spin-coating method, and the modified TNRAs were used as scaffold for the deposition of perovskite films and corresponding PSCs in air environment. The effect of NbCl 5 concentration on the micro structure and photovoltaic properties of the formed perovskite films were investigated, and the enhancement mechanism was also elucidated. A champion efficiency of 16.50% (enhanced of 9.49% compared with the pristine one) was achieved when the concentration of NbCl 5 solution was 0.005 M. Such an enhanced performance of PSC might be mainly ascribed to two reasons: one was the improved perovskite film qualities including the enlarged average grain size, higher crystallinity and reduced defect density; the other was the formed energy barrier (Nb 2 O 5 ) between perovskite layer and TNRAs interface that hindered the charge recombination.
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