Enhanced Electrochemical Performance of Aprotic Li-CO2 Batteries with a Ruthenium-Complex-Based Mobile Catalyst.

Li-CO2 batteries are regarded as next-generation high-energy-density electrochemical devices. However, the greatest challenge arises from the formation of the discharge product, Li2 CO3 , which would accumulate and deactivate heterogenous catalysts to cause huge polarization. Herein, Ru(bpy)3 Cl2 was employed as a solution-phase catalyst for Li-CO2 batteries and proved to be the most effective one screened so far. Spectroscopy and electrochemical analyses elucidate that the RuII center could interact with both CO2 and amorphous Li2 C2 O4 intermediate, thus promoting electroreduction process and delaying carbonate transformation. As a result, the charge potential is reduced to 3.86 V and over 60 discharge/charge cycles are achieved with a fixed capacity of 1000 mAh g-1 at a current density of 300 mA g-1 . Our work provides a new avenue to improve the electrochemical performance of Li-CO2 batteries with efficient mobile catalysts.

[Effects of deficit irrigation on water-radiation use and yield of Coffea arabica under different shade cultivation modes in dry-hot region]. / ä¸åŒè«è”½æ ½åŸ¹ä¸‹äºç¼ºçŒæº‰å¯¹å¹²çƒ­åŒºå°ç²’å’–å•¡æ°´å ‰åˆ©ç”¨å’Œäº§é‡çš„å½±å“.

The yield and quality of Coffea arabica cannot be guaranteed due to irrational irrigation and light management in dry-hot region. To investigate the best coupling mode of irrigation and shade cultivation of C. arabica in dry-hot region, a field experiment was carried out with different irrigation levels and shade cultivation modes. Three levels of irrigation, i.e., full irrigation, light deficit irrigation and severe deficit irrigation, and four modes of shade cultivation, i.e., no shade cultivation (C. arabica monoculture), light shade cultivation (intercropping of four-line C. arabica and a line banana), moderate shade cultivation (intercropping of three-line C. arabica and a line banana) and severe shade cultivation (intercropping of two-line C. arabica and a line banana) were designed to examine the effects of deficit irrigation on growth, photosynthetic characteristics of lea-ves, water-radiation use and yield of C. arabica under the shade of banana trees. The results showed that net photosynthesis rate (Pn), transpiration rate (Tr), stomatal conductance (gs), leaf water use efficiency (LWUE), leaf radiation use efficiency (LRUE) increased with the increases of irrigation amount, while the intercellular CO2 concentration (Ci) decreased with the increases of irrigation amount. Compared with full irrigation, light deficit irrigation decreased dry bean yield by 9.4%, severe deficit irrigation decreased dry bean yield and water use efficiency (WUE) by 36.7% and 16.9%, respectively. Pn, Tr, gs, LWUE first increased and then decreased with the increases of shading degree, with moderate shade cultivation having the maximum increment. Compared with no shade cultivation, light shade cultivation increased dry bean yield and WUE by 13.0% and 12.9%, respectively; moderate shade cultivation increased dry bean yield and WUE by 23.1% and 23.4%, respectively. The dry bean yield, WUE, volume and fresh mass of 100-bean of C. arabica increased in different degrees with the increases of irrigation amount and shading degree, with the largest enhancement of dry bean yield and WUE occurring in full irrigation under moderate shade cultivation. Soil water content in the same soil depth decreased with the increases of shading degree. Soil water content in the same place increased first and then decreased with the increases of soil la-yer depth in 0-50 cm soil layer. Results of regression analysis showed that LRUE had a significantly negative exponential relation or Logistic-curve variation with photosynthetically active radiation. Therefore, the suitable combination of irrigation treatment and banana shade cultivation mode for C. arabica was full irrigation and moderate shade cultivation, considering the comprehensive benefit of superior quality and high production and high efficiency water-radiation use.

[Coupling mode of irrigation and shading for good quality and proper yield of Coffea arabica in dry-hot region]. / 干热区小粒咖啡提质增产的灌水和遮荫耦合模式.

In a field experiment with three levels of irrigation, i.e., CI, DI75 and DI50(100%, 75% and 50% full irrigation) and four levels of shade, i.e., T100, T70, T55 and T40(100%, 70%, 55% and 40% natural radiation), the effects of irrigation and shading levels on growth, yield and quality of Coffea arabica were examined. The comprehensive benefit evaluation model was established under different irrigation and shading levels. The results showed that DI75 treatment increased the contents of fat and chlorogenic acid in dry bean by 6.0% and 10.2%, DI50 treatment significantly increased the content of caffeine of dry bean, but reduced water use efficiency. Compared with T100, T70 treatment increased the yield of dry bean and water use efficiency by 27.2% and 26.8%, respectively, and increased total sugar and chlorogenic acid content in dry bean by 6.3% and 5.5%. T55 and T40 treatments significantly reduced the yield of dry bean, water use efficiency, and the contents of caffeine and chlorogenic acid of dry bean. Compared with CIT100, DI75T70 treatment increased dry bean yield and water use efficiency by 28.0% and 44.5%, and increased the contents of total sugar, protein, fat and chlorogenic acid of dry bean by 12.2%, 14.7%, 6.6% and 10.0%, respectively, but reduced the concentration of caffeine by 8.3%. The comprehensive benefit of yield and quality of DI75T70 treatment (75% full irrigation, 70% natural radiation) was the best, which could implement good quality and proper yield of C. arabica.