Paper on stress-induced nonuniform intercalation in LiFePO4

Kaiqi has published a paper on modeling stress-induced non-uniform intercalation behavior in LiFePO4 in Journal of Materials Chemistry A (link). The simulation results exhibit very good agreement with a previous operando scanning transmission X-ray microscopy study and reveals that the coherency stress generated by the misfit strain between the Li-rich and Li-poor phases of the system destabilizes the lithium (de)intercalation front and leads to inferior electrode performance. It also shows that antisite defects promote the interface instability by allowing Li to move more freely along the [100] direction in the diffusion-limited regime. This draws an interesting contrast to our previous finding (published in npj Computational Materials) that antisite defects can benefit intercalation kinetics in the surface-reaction-limited regime. It paints a more complex picture of the defect effect and shows it is dependent on the phase transition mode. Here’s a news story on this work:  https://news.rice.edu/2020/01/14/not-so-fast-some-batteries-can-be-pushed-too-far/

 

Ming received DOE Early Career Award

Our project supported by the DOE Early Career Award officially kicked off. The project aims to obtain a mechanistic understanding of how a group of metals (zinc and alkali elements) with relevance to batteries develop unstable growth morphology during the electrodeposition process, a process important for the function of batteries. Many thanks to DOE BES for supporting this fundamental research.

https://www.energy.gov/articles/department-energy-selects-84-scientists-receive-early-career-research-program-funding

Understanding the role of stress in initiating lithium dendrite growth

A work we collaborated with Dr. Hanqing Jiang at Arizona State University just appeared in Nature Energy: https://www.nature.com/articles/s41560-018-0104-5           Good work, Liang and Fan!

Replacing graphite anode in current Li-ion batteries with lithium metal would boost energy density dramatically, but dendrite growth on Li surface during cycling is still a big problem. With our ASU collaborators, we made a fundamental discovery that electroplating induced stress in Li plays an enabling role in triggering dendrite growth. Hanqing’s group designed very cool experiments to show compress residual stress will accumulate in Li deposits during charging, and relieving the stress also eliminates dendrite growth. We proposed a stress-driven dendrite growth mechanism based on their observations. The phenomenon is actually quite similar to the well-known tin whisker growth phenomenon, but we’re perhaps the first to show their close analogy. This new understanding suggests stress relief could be an important component of an eventual winning solution to the Li dendrite problem. As a proof to that, Hanqing’s group developed a creative 3D soft substrate current collector for Li deposition. It shows very impressive cycling performance. Even better, it’s made from sugar! Take a read at this very nice piece written by Mike Williams, our senior media relation specialist at Rice: http://news.rice.edu/2018/03/08/sweet-relief-for-lithium-batteries-dendrite-problem-2/

 

 

Battery work published in Nature Communications

A paper by our group and collaborators at University of Wisconsin, Madison and MIT is recently published in Nature Communications. Dr. Liang Hong is a lead author and Fan is a co-author of the paper.

“Two-dimensional lithium diffusion behavior and probable hybrid phase transformation kinetics in olivine lithium iron phosphate”, https://www.nature.com/articles/s41467-017-01315-8

In this work, Dr. Linsen Li from Dr. Song Jin’s group at Wisconsin performed operando X-ray microscopy experiments on a common battery compound LiFePO4. We interpreted the experimental results with theoretical analysis and made a couple of notable findings, that is, 1) defects can fundamentally change Li diffusion behavior in this compound and may potentially benefit battery performance, and 2) there exists a hybrid phase transformation mechanism that is unique to intercalation compounds.

Here’s the news story on this work: http://news.rice.edu/2017/10/30/microscopic-defects-make-batteries-better-2/            It has been picked by multiple news outlets such as ScienceDaily, Futurity and PhysOrg.

Dr. Zhili Hu

Dr. Zhili Hu has recently accepted a faculty position at Nanjing University of Aeronautics and Astronautics (NUAA) in China and will start in the summer. Congratulations to Zhili and we wish him great success in his new endeavor!