可自愈阴极有望释放固态锂硫电池的潜力

Researchers have moved one step closer to making solid-state batteries from lithium and sulfur a practical reality. A team led by engineers at the University of California San Diego developed a new cathode material for solid-state lithium-sulfur batteries that is electrically conductive and structurally healable -- features that overcome the limitations of these batteries' current cathodes.
研究人员在实现锂硫固态电池实用化的道路上又迈进了一步。由加州大学圣地亚哥分校工程师领导的团队开发了一种新型固态锂硫电池阴极材料，该材料兼具导电性和结构自修复特性——这些特性克服了现有阴极材料的局限性。

The work was published in the journal Nature on March 6.
该研究于3月6日发表在《自然》杂志上。

Solid-state lithium-sulfur batteries are a type of rechargeable battery consisting of a solid electrolyte, an anode made of lithium metal and a cathode made of sulfur. These batteries hold promise as a superior alternative to current lithium-ion batteries as they offer increased energy density and lower costs. They have the potential to store up to twice as much energy per kilogram as conventional lithium-ion batteries -- in other words, they could double the range of electric vehicles without increasing the battery pack's weight. Additionally, the use of abundant, easily sourced materials makes them an economically viable and environmentally friendlier choice.
固态锂硫电池是一种可充电电池，由固体电解质、锂金属阳极和硫阴极组成。作为当前锂离子电池的优越替代品，这类电池展现出更高的能量密度和更低成本的优势。其单位重量储能可达传统锂离子电池的两倍——这意味着在不增加电池组重量的情况下，电动车辆的续航里程可翻倍。此外，使用丰富且易于获取的材料使其成为经济可行且更环保的选择。

However, the development of lithium-sulfur solid-state batteries has been historically plagued by the inherent characteristics of sulfur cathodes. Not only is sulfur a poor electron conductor, but sulfur cathodes also experience significant expansion and contraction during charging and discharging, leading to structural damage and decreased contact with the solid electrolyte. These issues collectively diminish the cathode's ability to transfer charge, compromising the overall performance and longevity of the solid-state battery.
然而，锂硫固态电池的发展历来受硫阴极固有特性的困扰。硫不仅导电性差，硫阴极在充放电过程中还会经历显著的膨胀与收缩，导致结构损坏以及与固态电解质的接触减少。这些问题共同削弱了阴极的电荷转移能力，影响了固态电池的整体性能与寿命。

To overcome these challenges, a team led by researchers at the UC San Diego Sustainable Power and Energy Center developed a new cathode material: a crystal composed of sulfur and iodine. By inserting iodine molecules into the crystalline sulfur structure, the researchers drastically increased the cathode material's electrical conductivity by 11 orders of magnitude, making it 100 billion times more conductive than crystals made of sulfur alone.
为克服这些挑战，由加州大学圣地亚哥分校可持续电力与能源中心研究人员领导的团队开发出一种新型阴极材料：由硫和碘构成的晶体。通过将碘分子嵌入晶体硫结构中，研究人员将该阴极材料的电导率提升了11个数量级，其导电性达到纯硫晶体的1000亿倍。

"We are very excited about the discovery of this new material," said study co-senior author Ping Liu, a professor of nanoengineering and director of the Sustainable Power and Energy Center at UC San Diego. "The drastic increase in electrical conductivity in sulfur is a surprise and scientifically very interesting."
"我们对这种新材料的发现感到非常兴奋，"研究的共同资深作者、加州大学圣地亚哥分校纳米工程学教授兼可持续电力与能源中心主任Ping Liu表示，"硫的电导率急剧增加令人惊讶，在科学上非常有趣。"

Moreover, the new crystal material possesses a low melting point of 65 degrees Celsius (149 degrees Fahrenheit), which is lower than the temperature of a hot mug of coffee. This means that the cathode can be easily re-melted after the battery is charged to repair the damaged interfaces from cycling. This is an important feature to address the cumulative damage that occurs at the solid-solid interface between the cathode and electrolyte during repeated charging and discharging.
此外，这种新型晶体材料的熔点仅为65摄氏度（149华氏度），比一杯热咖啡的温度还低。这意味着电池充电后，阴极可以轻松重新熔化，以修复循环过程中受损的界面。这一特性对于解决阴极与电解质在反复充放电过程中固-固界面累积损伤问题至关重要。

"This sulfur-iodide cathode presents a unique concept for managing some of the main impediments to commercialization of Li-S batteries," said study co-senior author Shyue Ping Ong, a professor of nanoengineering at the UC San Diego Jacobs School of Engineering. "Iodine disrupts the intermolecular bonds holding sulfur molecules together by just the right amount to lower its melting point to the Goldilocks zone -- above room temperature yet low enough for the cathode to be periodically re-healed via melting."
研究共同资深作者、UC San Diego Jacobs School of Engineering纳米工程学教授Shyue Ping Ong表示："这种硫碘阴极为解决锂硫电池商业化主要障碍提供了独特方案。碘通过精准破坏硫分子间的分子间键，将其熔点降至'适宜区间'——既高于室温，又足够低使阴极能通过周期性熔融实现自我修复。"

"The low melting point of our new cathode material makes repairing the interfaces possible, a long sought-after solution for these batteries," said study co-first author Jianbin Zhou, a former nanoengineering postdoctoral researcher from Liu's research group. "This new material is an enabling solution for future high energy density solid-state batteries."
“我们新型阴极材料的低熔点使得修复界面成为可能，这是这些电池长期以来梦寐以求的解决方案，”该研究的共同第一作者、来自刘研究组的纳米工程博士后研究员周建斌（音译）说。“这种新材料为未来高能量密度固态电池提供了一种可行的解决方案。”

To validate the effectiveness of the new cathode material, the researchers constructed a test battery and subjected it to repeated charge and discharge cycles. The battery remained stable for over 400 cycles while retaining 87 percent of its capacity.
为验证新型阴极材料的有效性，研究人员构建了一个测试电池并对其进行反复充放电循环。该电池在400次循环后仍保持稳定，容量保留率达87%。

"This discovery has the potential to solve one of the biggest challenges to the introduction of solid-state lithium-sulfur batteries by dramatically increasing the useful life of a battery," said study co-author Christopher Brooks, chief scientist at Honda Research Institute USA, Inc. "The ability for a battery to self-heal simply by raising the temperature could significantly extend the total battery life cycle, creating a potential pathway toward real-world application of solid-state batteries."
"这一发现有可能解决固态锂硫电池应用中的最大挑战之一，即通过大幅延长电池的使用寿命，"研究合著者、美国本田研究所首席科学家克里斯托弗·布鲁克斯表示，"电池仅通过升温就能自我修复的Ability可显著延长整体电池生命周期，为固态电池的实际应用开辟潜在路径。"

The team is working to further advance the solid-state lithium-sulfur battery technology by improving cell engineering designs and scaling up the cell format.
该团队正致力于通过改进电池工程设计和扩大电池规格，进一步推进固态锂硫电池技术的发展。

"While much remains to be done to deliver a viable solid state battery, our work is a significant step," said Liu. "This work was made possible thanks to great collaborations between our teams at UC San Diego and our research partners at national labs, academia and industry."
"虽然要实现可行的固态电池还有很多工作要做，但我们的研究迈出了重要一步，"刘说。"这项成果得益于我们UC San Diego团队与来自国家实验室、学术界和工业界研究伙伴的通力合作。"

This work was supported in part by the U.S. Department of Energy (DOE) Advanced Research Projects Agency-Energy (DE-AR0000781), the U.S. DOE Office of Science (DEAC02-05-CH11231).
本研究部分由美国能源部（DOE）高级能源研究计划署（DE-AR0000781）和美国能源部科学办公室（DEAC02-05-CH11231）资助。

Disclosures: Ping Liu and Jianbin Zhou report a U.S. provisional patent application filed on February 13, 2023, Serial No. _63/484,659, based on this work.
披露声明：刘平和周建斌基于此项工作于2023年2月13日提交了美国临时专利申请，序列号为_63/484,659。