Proximate, mineral and anti-nutrient compositions of oat grains (Avena sativa) cultivated in Ethiopia: implications for nutrition and mineral bioavailability.

Oat (Avena sativa) is an underutilized cereal grain in Ethiopia from the Poaceae grass family. This study aimed to investigate the proximate, mineral, and anti-nutrient composition of three landrace varieties commonly used in certain districts of the country and compare them with two improved varieties of oats in Ethiopia. The proximate and mineral composition was determined using the Association of Official Analytical Chemists (AOAC) standard methods. Phytate and tannin contents were determined using the spectroscopic method, and oxalate was analyzed using HPLC. The bioavailability of minerals was also estimated. Results showed significant (p < 0.05) differences in proximate, mineral, and anti-nutrient compositions among studied varieties. The moisture, crude protein, crude fat, crude fiber, ash, and total carbohydrate contents were in the range between 8.5-9.8, 11.9-15.8, 6.7-10.3, 2.1-3.5, 1.2-1.3, and 72.6-74.3 g/100 g DM, respectively. Iron, copper, zinc, magnesium, calcium, and potassium contents were 2.5-3.0, 0.2-0.4, 1.6-2.0, 62.4-89.1, 44.0-102.7, and 241.7-258.3 mg/100 g DM, respectively. The oxalate, tannin, and phytate contents ranged from 28.2-71.4, 38.8-51.5, and 269.6-293.0 mg/100 g DM, respectively. Except for a few varieties of oats, the molar ratios were below the critical values. Results showed that both the landraces and improved varieties studied are an excellent source of valuable nutrients. Thus, the production and utilization of this crop in a few geographical locations and communities should be further encouraged in the rest areas of the country to benefit from this underutilized but nutritious crop.

Multilayer-graphene-stabilized lithium deposition for anode-Free lithium-metal batteries.

The will to circumvent capacity fading, Li dendrite formation, and low coulombic efficiency in anode-free Li-metal batteries (AFLMBs) requires a radical change in the science underpinning new materials discovery, battery design, and understanding electrode interfaces. Herein, a Cu current collector formed with ultrathin multilayer graphene grown via chemical vapor deposition (CVD) was used as an artificial layer to stabilize the electrode interface and sandwich-deposited Li with Cu. A multilayer graphene film's superior strength, chemical stability, and flexibility make it an excellent choice to modify a Cu electrode. Fabricating an anode bigger than the cathode improved the alignment of the electrodes during assembly, minimizing interfacial stress. Here, 19 mm electrodes when paired with a commercial LiFePO4 cathode (mass loading: ∼12 mg cm-2) delivered the first-cycle discharge capacities of 147 and 151 mA h g-1 for bare and multilayer-graphene-protected electrodes, respectively, which could alleviate the big hurdle (initial capacity loss) in anode-free batteries. After 100 round-trip cycles, bare Cu and multilayer-graphene-protected electrodes retained ∼46 and ∼61% of their initial capacities, respectively, in an ether-based electrolyte at the rate of 0.1 C.

Polyethylene oxide film coating enhances lithium cycling efficiency of an anode-free lithium-metal battery.

The practical implementation of an anode-free lithium-metal battery with promising high capacity is hampered by dendrite formation and low coulombic efficiency. Most notably, these challenges stem from non-uniform lithium plating and unstable SEI layer formation on the bare copper electrode. Herein, we revealed the homogeneous deposition of lithium and effective suppression of dendrite formation using a copper electrode coated with a polyethylene oxide (PEO) film in an electrolyte comprising 1 M LiTFSI, DME/DOL (1/1, v/v) and 2 wt% LiNO3. More importantly, the PEO film coating promoted the formation of a thin and robust SEI layer film by hosting lithium and regulating the inevitable reaction of lithium with the electrolyte. The modified electrode exhibited stable cycling of lithium with an average coulombic efficiency of ∼100% over 200 cycles and low voltage hysteresis (∼30 mV) at a current density of 0.5 mA cm-2. Moreover, we tested the anode-free battery experimentally by integrating it with an LiFePO4 cathode into a full-cell configuration (Cu@PEO/LiFePO4). The new cell demonstrated stable cycling with an average coulombic efficiency of 98.6% and capacity retention of 30% in the 200th cycle at a rate of 0.2C. These impressive enhancements in cycle life and capacity retention result from the synergy of the PEO film coating, high electrode-electrolyte interface compatibility, stable polar oligomer formation from the reduction of 1,3-dioxolane and the generation of SEI-stabilizing nitrite and nitride upon lithium nitrate reduction. Our result opens up a new route to realize anode-free batteries by modifying the copper anode with PEO to achieve ever more demanding yet safe interfacial chemistry and control of dendrite formation.