Due to their high energy density, lithium-ion batteries have a very broad range of applications.

Whether it is the laptops, mobile phones, and watches that are ubiquitous in our daily lives, or high-tech products such as new energy vehicles and drones, they all rely on lithium-ion batteries as their main driving force.

The cathode and anode materials of lithium-ion batteries jointly affect their energy density.

For lithium-ion batteries that have been commercially applied, graphite is the most commonly used anode material, with a theoretical specific capacity of about 350 milliampere-hours per gram.

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When it is matched with layered metal oxide cathode materials, the theoretical energy density can achieve 300 watt-hours per kilogram, and the highest actual energy density that can be achieved is approximately between 200 and 250 watt-hours per kilogram.Compared to the graphite anode, the theoretical specific capacity of the metallic lithium anode is 4 to 5 times higher.

The assembled full cell with layered metal oxide cathode materials is expected to break through an energy density of 500 watt-hours per kilogram, which is about twice as high as that of traditional lithium-ion batteries.

Therefore, in order to meet the demand for high energy density battery systems in related fields, lithium metal batteries with metallic lithium as the anode are gradually becoming an important research hotspot.

However, from the current perspective, the primary challenge to be overcome for the practical application of lithium metal batteries is the safety issue.

This is because, although metallic lithium has a high energy density, its chemical properties are very reactive, and it will undergo side reactions when it comes into contact with most organic solvents.At the same time, the deposition and stripping behavior of lithium during the charging and discharging process are uncontrollable, which can lead to the growth of special morphologies on the surface, such as dendrites, and then puncture the battery separator.

It should be noted that the separator is a thin and soft membrane material between the positive and negative electrodes. If it is punctured, it will cause the positive and negative electrodes to connect, leading to a short circuit and thermal runaway.

To address safety issues, it is necessary to first understand the causes of failure in lithium metal batteries in order to further build an intrinsically safe battery system.

Therefore, qualitative and quantitative analysis of the solid electrolyte interphase (SEI) of lithium metal batteries is extremely important. This is also the research direction that Professor Zulpiyah Sadiq of Shanghai Jiao Tong University has been focusing on for many years.

By confirming that lithium fluoride and lithium hydride are the main components of the metal lithium anode interface and establishing a battery failure model, she has provided important ideas for the optimization of the metal lithium anode interface and the development of ultra-high energy density battery systems. As a result, she has become one of the Chinese winners of the "35 Innovators Under 35" in the 2023 MIT Technology Review.Unveiling New Mechanisms of Lithium Metal Battery Interfaces to Promote the Construction of High-Energy Battery Systems

The Solid Electrolyte Interphase (SEI) is a distinct thin film between the lithium metal anode (solid) and the electrolyte (liquid).

Scientists in this field have discovered through long-term research that the thickness of this film is roughly between a few nanometers to several tens of nanometers.

"The film not only has crystalline components but also a significant amount of amorphous components. Although there are already relatively complete methods for characterizing the former, characterizing the structure of the latter still poses a considerable challenge," she stated.

In response, she first used synchrotron radiation X-ray diffraction technology to qualitatively and quantitatively analyze the crystalline components of the lithium anode surface SEI produced in different electrolyte systems.However, due to the fact that synchrotron X-ray diffraction technology only includes Bragg diffraction, it is unable to analyze the amorphous phase components.

So, she further utilized the pair distribution function technique to analyze the solvation structure of the electrolyte and the amorphous phase components in the SEI, in order to study the impact of electrolyte concentration on the SEI composition.

Based on the synchrotron X-ray diffraction technology, pair distribution function analysis, and fitting results, the research group has drawn the following key conclusions.

Firstly, compared with the conventional bulk lithium fluoride (LiF), the X-ray diffraction peak of (LiF)SEI in the SEI is broader, the lattice parameters are larger, and the grains are smaller.

Due to the unique crystal structure of (LiF)SEI, small grains usually result in larger lattice parameters, and small grains are conducive to the transport of lithium ions at grain boundaries.Secondly, in addition to LiF, lithium hydride (LiH) is also one of the main components of the SEI (Solid Electrolyte Interphase).

In fact, over the past few decades, the presence of LiH in the SEI has not been confirmed in the relevant literature.

It is believed that there may be several reasons why previous studies failed to detect LiH.

Firstly, both LiH and LiF have a face-centered cubic lattice structure, and their unit cell parameters are very close, so many previous reports may have mistaken LiH for LiF.

Secondly, LiH is extremely unstable in air, and even a few seconds of exposure can cause it to oxidize and decompose, making it difficult to detect.To validate the accuracy of their experimental results, the team also spent approximately one year to repeatedly confirm their findings.

Ultimately, through in-situ X-ray diffraction experiments, researchers monitored in real-time the compositional changes of the SEI samples during the process of exposure to air, further confirming the presence of LiH in the SEI, and emphasizing the importance of avoiding exposure of the SEI samples to air during testing.

Thirdly, there is a significant difference in the components of the SEI produced in high and low concentration electrolyte systems.

Among them, the SEI produced in the low concentration electrolyte system mainly comes from the decomposition of solvent molecules, while the SEI produced in the high concentration electrolyte contains a large amount of polymers and (LiF)SEI produced by the decomposition of lithium salts, which is conducive to the formation of a stable SEI, thereby improving the Coulomb efficiency and cycle stability of the lithium metal anode.

Additionally, it is worth noting that due to the very similar lattice parameters of LiH and LiF, they can form a LiFxH1-x solid solution phase, which will greatly improve the lithium ion conductivity.Ultimately, the relevant paper was published in Nature Nanotechnology with the title "Identification of LiH and nanocrystalline LiF in the solid-electrolyte interphase of lithium metal anodes" [1].

For this achievement, the U.S. Department of Energy has also commented: "Shadike revealed a new mechanism for the production of lithium metal solid electrolyte interphase films, which will promote the development and application of low-cost, ultra-light, and ultra-thin battery systems. [2]"

Adhering to the principle of "learn to learn - learn well - teach well," she will continue to delve deeply into secondary battery technology.

As a post-90s Uyghur girl, Zulpiyah comes from an intellectual family in the Kashgar region of Xinjiang.

Whether it is her father, a technical staff member, or her mother, a medical staff member, they have both made outstanding achievements in their respective positions. At the same time, they also love to read literature, science and technology, and other types of books.This proactive work attitude and thirst for knowledge have had a subtle influence on her since childhood, helping her grow into a character that is independent in thought, unafraid of difficulties, and lively and cheerful.

At the same time, many teachers during her primary and secondary school years also played an important guiding role in her growth.

They often talked about their own experiences when studying in Shanghai, and also told the students about the prosperity and development of Shanghai, as well as the charm of famous schools such as Shanghai Jiao Tong University and Fudan University.

Under the influence of the teachers, the longing for Shanghai arose spontaneously in her heart. "Must be admitted to a university in Shanghai" has also become her biggest dream during the middle school stage.

In 2008, she was admitted to Shanghai Jiao Tong University."Chemistry has always been a subject that I am very interested in. Because I was deeply attracted by those unique and interesting chemical phenomena in high school chemistry experiments, I chose to study Chemical Engineering and Technology as my undergraduate major," she said.

In 2012, Zulipiyah was recommended for postgraduate study at Fudan University due to her excellent academic performance during her undergraduate studies, under the guidance of Professor Fu Zhengwen.

"After more than a year of academic research in the research group, I found that I had developed a strong interest in the field of batteries, so I began to apply for a combined master's and doctoral program to continue my graduate studies," she said.

In 2017, she came to the Brookhaven National Laboratory of the U.S. Department of Energy to engage in postdoctoral research, with Professor Yang Xiaoqing as her collaborating mentor.

In June 2021, she officially joined her alma mater, Shanghai Jiao Tong University, as an associate professor.In her view, as a scientific researcher and university professor, she bears the mission of exploring the unknown fields, and needs to promote the progress of the discipline by developing new technologies and innovative thinking, solving existing bottleneck problems, thereby providing momentum for social development.

And she will also go through the process of "learning to learn - learning - teaching", and through the inheritance of knowledge, gather the youthful strength for the development of the country's related fields.

In fact, her own scientific research and teaching experience is a good practice of "learning to learn - learning - teaching".

Specifically, during the master's and doctoral continuous study phase, her scientific research progress was not so smooth, and the entire research process was very slow.

Especially in the first and second years of the doctorate, her classmates around her have published a lot of articles one after another, but she is still constantly learning a large amount of professional knowledge involved in the research topic, almost every day the time of learning and working is between 16 to 17 hours."Although these two years were very tough for me, I now look back and feel that I gained the most, which made me understand what it means to 'learn well,'" she said.

During her postdoctoral stage, she began to embark on the path of "learning well," that is, how to apply the basic knowledge she learned in the previous graduate stage to practical systems.

"The status of a postdoctoral fellow is completely different from that of a student. Not only do we have to complete all the research on our own, but we also need to assist our mentors in writing projects, as well as guide undergraduate and graduate students," she said.

In the two or three years after joining Shanghai Jiao Tong University, Zuli Piya completed the transformation from "learning well" to "teaching well."

"In addition to conducting research at the university, we also have the responsibility of teaching students. But just because I can learn a piece of knowledge does not mean I can teach it. How to combine the cutting-edge science of our field with our own courses and teach it to students in a more interesting way is a challenge we need to face," she said.In her view, the concentrated training over the past two or three years has led to significant growth for her.

"Now standing on the podium, I finally feel that I am a better teacher," she said.

And in the future, she plans to use interdisciplinary integration as a characteristic research method to further clarify the intrinsic connections between the composition, structure, and electrochemical properties of high-energy-density electrode materials, to build a stable cathode material model, and to lay a solid theoretical foundation for scientific research and new technology development in the field of secondary batteries.