Synthetic biomaterials can be used as instructive biological milieus to guide cellular behaviour and function. To further realize this application, we synthesized a series of structurally similar hydrogels and tested their ability to modulate angiogenesis. Hydrogels were synthesized from poly(DTE-co-x% DT carbonate) crosslinked by y% poly(ethylene glycol) (PEG). Hydrogel desaminotyrosyl tyrosine (DT) contents (x%) ranged from 10-100%, and crosslink densities (y% PEG-crosslinker) ranged from 5-80%. The hydrogels were fashioned into porous scaffolds with highly interconnected macro-and micro-pore (>100 and <10 μm in diameter, respectively) architecture using poly(DTE-co-10%DT carbonate) crosslinked with 8% PEG. Under physiological conditions (in vitro), the hydrogels degraded into three major products: desaminotyrosyltyrosine ethyl ester (DTE), desaminotyrosyl tyrosine (DT), and poly(ethylene glycol)-di-DT-hydrazide (PEG-di-DT hydrazide). Increasing either DT content or crosslink density brought quickened degradation. Because DT and DTE, two of the three major degradation products, have not demonstrated any noticeable cytotoxicity or angiogenic effect in previous studies, we measured the cytotoxicity of PEG-di-DT hydrazide, the third major degradation product. We found that PEG-di-DT hydrazide only displayed significant cytotoxicity at the high concentration of 100 mg/mL. Interestingly, PEG-di-DT hydrazide and its further degradation product PEG-dihydrazide stimulated in vitro endothelial cell migration and tubulogenesis, which is comparable to results found with FGF-β treatment. Subcutaneous implantation of the PEG-crosslinked poly(DTE-co-10%DT carbonate) scaffolds into the backs of rats elicited greater tissue growth over time and superior vascularization than poly(DTE carbonate) implantation. These results show that this new class of biomaterials has a strong potential to modulate angiogenesis.

Zinc (Zn)–manganese dioxide (MnO2) rechargeable batteries have attracted research interest because of high specific theoretical capacity as well as being environmentally friendly, intrinsically safe and low-cost. Liquid electrolytes, such as potassium hydroxide, are historically used in these batteries; however, many failure mechanisms of the Zn–MnO2 battery chemistry result from the use of liquid electrolytes, including the formation of electrochemically inert phases such as hetaerolite (ZnMn2O4) and the promotion of shape change of the Zn electrode. This manuscript reports on the fundamental and commercial results of gel electrolytes for use in rechargeable Zn–MnO2 batteries as an alternative to liquid electrolytes. The manuscript also reports on novel properties of the gelled electrolyte such as limiting the overdischarge of Zn anodes, which is a problem in liquid electrolyte, and finally its use in solar microgrid applications, which is a first in academic literature. Potentiostatic and galvanostatic tests with the optimized gel electrolyte showed higher capacity retention compared to the tests with the liquid electrolyte, suggesting that gel electrolyte helps reduce Mn3+ dissolution and zincate ion migration from the Zn anode, improving reversibility. Cycling tests for commercially sized prismatic cells showed the gel electrolyte had exceptional cycle life, showing 100% capacity retention for >700 cycles at 9.5 Ah and for >300 cycles at 19 Ah, while the 19 Ah prismatic cell with a liquid electrolyte showed discharge capacity degradation at 100th cycle. We also performed overdischarge protection tests, in which a commercialized prismatic cell with the gel electrolyte was discharged to 0 V and achieved stable discharge capacities, while the liquid electrolyte cell showed discharge capacity fade in the first few cycles. Finally, the gel electrolyte batteries were tested under IEC solar off-grid protocol. It was noted that the gelled Zn–MnO2 batteries outperformed the Pb–acid batteries. Additionally, a designed system nameplated at 2 kWh with a 12 V system with 72 prismatic cells was tested with the same protocol, and it has entered its third year of cycling. This suggests that Zn–MnO2 rechargeable batteries with the gel electrolyte will be an ideal candidate for solar microgrid systems and grid storage in general.

Zinc (Zn)-anode batteries, although safe and non-flammable, are precluded in promising applications because of their low voltage (<2V) and poor rechargeability. Here, we report the demonstration of rechargeable membrane-less Zn-anode...

Zinc|Manganese Dioxide (Zn|MnO2) are widely available as primary batteries for use in small-scale consumer electronics because of its low cost and high energy density. The last decade has seen a resurgence in research to make this chemistry rechargeable by materials engineering, additives and experimenting with various electrolytes. These important contributions have showed that Zn|MnO2 has all the prerequisites to be a post-lithium solution for grid-scale storage. At Urban Electric Power, we have been commercializing proton-insertion Zn|MnO2 batteries in cylindrical and prismatic form factors between 70 to 140Ah nameplate capacity. These batteries contain improved materials and electrode designs with improved utilizations of the cathode and anode theoretical capacity. Both the cathode and anode can achieve 40 to 60% of their theoretical capacity, which is currently the best in alkaline electrolytes and scaled-up cells. These improvements not only reflect the performance but also the manufacturability of cells on a large scale. In this talk, we will present the methodological approach we pursued to achieve these performance metrics and reduce the cost to <$80/kWh. We also cycled these cells according to various protocols that represent real world applications. For example, we found that the newly improved Zn|MnO2 cells can achieve >6 years of performance for solar microgrid applications, which is better than lead acid batteries, the current battery of choice. We have also manufactured gelled Zn|MnO2 batteries that can be considered as “non-spillable” and thus, “non-hazardous” according to transportation regulations. These non-spillable cells manufacturing process and performance will also be presented in the talk. The talk will also expand on the future generations of Zn|MnO2 that are currently under development at Urban Electric Power like the conversion battery which access the complete 2nd electron capacity of the electrodes and the high voltage (>2.5V) battery. These batteries expand the application space of Zn|MnO2 batteries which make it a viable contender for post lithium-ion batteries.

Alkaline zinc (Zn)-manganese dioxide (MnO2) batteries are ubiquitous, safe, cheap and used in several applications that require only a single discharge. Its impact in the developing world has been significant where its affordability has helped consumers with low to medium economic background power several of their household devices and flashlights when grid reliability has been poor. Its single discharge is enough to deliver an energy density of ~400Wh/L. However, its promising characteristics are outweighed by its limited use in the next generation of green energy technologies because of the irreversibility of its active materials and its low nominal voltage of ~1.3V. The application of battery energy storage in these next generation of technologies like grid-storage, electric vehicles and personal electronics is extremely vital to decarbonize our future. Currently, expensive, toxic and flammable lithium-ion and lead acid batteries dominate these fields. If Zn-MnO2 batteries could be made rechargeable with an increase in its nominal voltage and capacity utilized, it could be serious contender to the dominant lithium-ion and lead acid batteries. In this presentation, we report on an innovative approach where we solve the two aforementioned issues by redesigning the battery system to have two electrolytes that are decoupled from each other(1). The two electrolytes are aqueous-based, where the cathode and anode are immersed in mildly acidic solutions and alkaline solutions, respectively. Operating in decoupled electrolytes allows the chemistry to widen its potential window and access voltages of >2.85V, while also allowing the respective electrodes operate efficiently and reversibly in their respective electrolyte system. The neutralization of these electrolytes is prevented by gelation of the alkaline electrolyte, which removes the need of expensive ion-exchange membranes. As a demonstration of this concept, we have developed Zn-MnO2 batteries reaching voltages >2.85V that are able to access the theoretical capacity (617mAh/g) of MnO2. This translates to energy densities 2 to 3 times greater than the commercially available alkaline batteries that can be recharged multiple times at costs that are comparable to primary batteries (~$20-30/kWh). G. Yadav et al., ACS Energy Lett. 2019, 4(9), 2144-2146.