SBIR Phase II: Liquefied Gas Electrolytes for High Energy Density Energy Storage Devices

这个小型企业创新研究(SBIR)第二阶段项目的重点是开发使用新型液化气电解液的锂金属电池。虽然全球正在大力推进下一代锂电池的电解液化学，但这些努力几乎完全集中在液体和固态电解液上。相比之下，该项目旨在进一步开发一种新型电解液的使用，这种电解液使用的溶剂通常在室温下是气态的，在中等压力下会液化。第一阶段的工作展示了世界纪录的循环锂金属，400次循环的平均电镀/剥离库仑效率为99.5%(每个循环0.5 mA/cm2和0.5 mAh/cm2)，通过低温聚焦离子束表征观察到平滑和高密度的锂沉积。此外，在-80℃下，锂基电解液的低温电导率达到了3ms/cm的世界纪录，远远超过了最先进的水平。最后，由于盐析出降低了电解液的电导率，在+40℃发生了可逆的高温关断。这种高温关闭基本上消除了热失控反应的发生，从而使电池更加安全。通过NSF第二阶段拨款进一步开发这些电解液，将使进一步的工作能够将电池比能量提高到450瓦时/公斤，将工作温度从-60℃扩大到+60℃，并提高安全性，而不会发生热失控，同时保持与传统锂离子电池相当的功率和循环寿命。这将通过进一步发展电解液化学，将锂金属库仑效率提高到1000次循环的99.8%，将高温关闭提高到+60~70℃，将正极性能提高到更高的电压和循环寿命，以及开发一条高通量研发线，提供高精度的电解液成分添加来微调化学。由于电解液化学可能使用几种常见的材料和制造方法，应该有低成本壁垒进入市场，预计批量生产的成本将大幅降低，降至100美元/千瓦时的目标。开发的技术将特别适合于低温应用，如高大气、国防和航空航天，这些应用经常承受极端温度，需要高比能量。由于与现有技术相比，南八科技在低温下的性能优越，因此南八科技将首先专注于开发这些领域的技术。随着技术的成熟，最终将进入电网存储和运输市场，导致排放和对进口燃料的依赖大幅减少。这些新材料的潜在基础化学是一个相对较新的领域，可能会导致下一代储能设备和更广泛技术的重大进步，导致新的行业、就业增长和其他领域。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This Small Business Innovation Research (SBIR) Phase II project is focused on the development of a lithium metal battery using a novel Liquefied Gas Electrolyte. While there is an intense global effort to advance electrolyte chemistry for next-generation lithium batteries, these efforts focus almost entirely on liquid and solid-state electrolytes. In contrast, this project aims to further develop the use of a novel class of electrolytes which use solvents that are typically gaseous at room temperature and liquefied under moderate pressures. Phase I work demonstrated world-record cycling lithium metal with an average plating/stripping coulombic efficiency of 99.5% over 400 cycles with (0.5 mA/cm2 and 0.5 mAh/cm2 each cycle) with smooth and highly dense lithium deposition as observed through cryogenic focused-ion-beam characterization. Further, a world-record low temperature electrolytic conductivity of 3 mS/cm at -80 ?C for lithium-based electrolytes was obtained, far exceeding the state-of-art. Lastly, a reversible high temperature shut-down at +40 ?C, due to a decrease in electrolyte conductivity from salt precipitation, was demonstrated. This high temperature shut-down essentially eliminates thermal runaway reaction from occurring, making for a significantly safer battery.Further development of these electrolytes through this NSF Phase II grant will enable further work to increase battery specific energy to 450 Wh/kg, expand operating temperatures from -60 to +60 ?C, and increased safety with no thermal runaway while maintaining power and cycle life comparable to conventional Li-ion. This will be accomplished with further development of the electrolyte chemistry to improve lithium metal coulombic efficiency to 99.8% over 1000 cycles, increase the high temperature shut-down to +60~70 ?C, increasing cathode performance to higher voltages and cycle life, and the development of a high throughput R&D line which will offer high precision addition of electrolyte components to fine tune the chemistry. Because the electrolyte chemistry may use several common materials and manufacturing methods, there should be low cost barrier to entry and it is expected there will be significant cost reduction in volume production down to the goal of $100/kWh. The developed technology will be especially well suited for low temperature applications such as high-atmosphere, defense, and aerospace which frequently endure extreme temperatures and require high specific energy. Because of the superior performance at low temperatures compared to the incumbent, South 8 Technologies will first focus on developing the technology in these areas. As the technology matures, an eventual move into grid storage and transportation markets will follow, leading to a substantial decrease in emissions and reliance on imported fuels. The underlying fundamental chemistry with these new materials is a relatively new field and may potentially lead to significant advances in next-generation energy storage devices and broader technologies, leading to new industries, job growth and beyond.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.