Qingxiao Meng,Jianyong Feng,Huiting Huang,Xiaopeng Han,Zhi Zhu,Tao Yu,Zhaosheng Li,Zhigang Zou
Both phase and morphology of perovskite films are very important for high-performance optoelectronic devices. Although a two-step method based on CsBr ethylene glycol monomethylether (EGME) solution can prepare pure-phase CsPbBr 3 films, they have a poor morphology due to excessive Ostwald ripening. Herein, a bi-solvent engineering strategy is demonstrated to simultaneously optimize phase and morphology of CsPbBr 3 films in a two-step solution method, which uses the bi-solvents of EGME and isopropanol (IPA) instead of EGME for CsBr solution at the second step. Optimizing the volume ratio of bi-solvents and immersion time can control the Ostwald ripening effectively and result in pure-phase, compact, and smooth CsPbBr 3 films. Finally, the prepared films are applied to perovskite solar cells (PSCs) with a structure of fluorine-doped tin oxide (FTO)/compact TiO 2 (c-TiO 2 )/CsPbBr 3 /carbon. In comparison with EGME, the champion power conversion efficiency (PCE) of devices from EGME/IPA bi-solvents increases from 3.57% to 7.29% owing mainly to higher coverage, smoother surface, and lower trap density of CsPbBr 3 films from EGME/IPA bi-solvents. This work provides a simple and efficient method for the preparation of high-quality CsPbBr 3 films.
Currently, with the increasingly stringent requirements of carbon emissions and the rapid development of the new energy industry, the strategic position of lithium has been elevated unprecedentedly. Improving the lithium yield in the ore lithium extraction process is very important for the sustainable development of the lithium production industry. In this study, the by-product mirabilite from the lithium hydroxide production was treated as the material to deeply recover lithium. The effect factor of equilibrium extraction, the separation mechanism, and the removal of residual organic matter was discussed. The results showed that the optimized organic phase composed of 0.5 M 1-benzoyl-2-nonanone(HBNA) and 0.5 M trialkyl phosphine oxide(TRPO) could effectively extract lithium from mirabilite dissolved solution, and 99% of lithium could be recovered through 3-stage countercurrent extraction under the condition of O/A = 1/1, mixing time = 5 min, and temperature = 20 °C. The 95% of co-extracted sodium in the loaded organic could be easily eluted by 0.5 M HCl at an O/A = 10/1, and afterward, the lithium in the organic phase could be concentrated to 25 g/L through stripping by HCl or H 2 SO 4 . The dissolved organic matter in the extraction raffinate was deeply removed by the resin adsorption method under the condition of pH = 2.0, adsorption time = 4 h, and solid to liquid ratio = 1/5. The DFT study demonstrated that the complexes have the lowest energy and the most stable structure when the stoichiometric ratio of Li, HBNA, and TRPO is 1:1:1 and a dimer is formed. This process provided a novel approach to improving the lithium recovery of lithium hydroxide production.
Nickel-rich cobalt-free layered oxide cathode with Ni contents no fewer than 90 % has received extensive attention in the field of lithium-ion batteries due to its excellent specific capacity and low cost, but serious capacity degeneration induced by structural deterioration and interfacial instability greatly hamper their further development. Herein, the Sb-modified LiNi 0.9 Mn 0.1 O 2 materials from the interface to interior have been designed and fabricated to overcome the above issues. On the one hand, the introduction of Sb-ion in interior of grains can generate Sb-O chemical bond with high dissociation energy, which contributes to reinforce the chemical and structural stability. Meanwhile, the existence of Sb-ions can restrain the harmful H2-H3 phase transformation and expand interlayer spacing, thereof enabling to weaken the mechanical stress and enhance ion diffusion rate. On the other hand, the surficial modification resulted by the Sb-based materials can effectively suppress the noxious interfacial reaction, which is conducive to improving the cycling stability. As expected, the capacity retention rate of NM-Sb materials prepared by this optimized design in this work reached 89.5 % after 200 cycles at 1 C. Thus, the constructed double-modification is essential for obtaining robust framework and enhancing interfacial stability for high-performance nickel-rich cobalt-free lithium-ion battery cathode materials.
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