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1. Battery Internal Short Detection Methodology Using Cell Swelling Measurements

   https://doi.org/10.23919/ACC45564.2020.9147956  

   Cai, Ting ; Pannala, Sravan ; Stefanopoulou, Anna G. ; Siegel, Jason B. ( July 2020 , 2020 American Control Conference (ACC))

   Li-ion battery internal short circuits are a major safety issue for electric vehicles, and can lead to serious consequences such as battery thermal runaway. An internal short can be caused by mechanical abuse, high temperature, overcharging, and lithium plating. The low impedance or hard internal short circuit is the most dangerous kind. The high internal current flow can lead to battery temperature increase, thermal runaway, and even explosion in a few seconds. Algorithms that can quickly detect such serious events with a high confidence level and which are robust to sensor noise are needed to ensure passenger safety. False positives are also undesirable as many thermal runaway mitigation techniques, such as activating pyrotechnic safety switches, would disable the vehicle. Conventional methods of battery internal short detection, including voltage and surface temperature based algorithms, work well for a single cell. However, these methods are difficult to apply in large scale battery packs with many parallel cells. In this study, we propose a new internal short detection method by using cell swelling information during the early stages of a battery heating caused by an internal short circuit. By measuring cell expansion force, higher confidence level detection can be achieved for an internalmore »short circuit in an electric vehicle scale battery pack.« less
2. Solid-state rigid-rod polymer composite electrolytes with nanocrystalline lithium ion pathways

   https://doi.org/10.1038/s41563-021-00995-4  

   Wang, Ying ; Zanelotti, Curt J. ; Wang, Xiaoen ; Kerr, Robert ; Jin, Liyu ; Kan, Wang Hay ; Dingemans, Theo J. ; Forsyth, Maria ; Madsen, Louis A. ( May 2021 , Nature Materials)

   Dusastre, Vincent (Ed.)

   A critical challenge for next-generation lithium-based batteries lies in development of electrolytes that enable thermal safety along with use of high-energy-density electrodes. We describe molecular ionic composite (MIC) electrolytes based on an aligned liquid crystalline polymer combined with ionic liquids and concentrated Li salt. This high strength (200 MPa) and non-flammable solid electrolyte possesses outstanding Li+ conductivity (1 mS·cm-1 at 25 °C) and electrochemical stability (5.6 V vs Li|Li+) while suppressing dendrite growth and exhibiting low interfacial resistance (32 Ω·cm2) and overpotentials (≤ 120 mV @ 1 mA·cm-2) during Li symmetric cell cycling. A heterogeneous salt doping process modifies a locally ordered polymer-ion assembly to incorporate an inter-grain network filled with defective LiFSI & LiBF4 nanocrystals, strongly enhancing Li+ conduction. This modular material fabrication platform shows promise for safe and high-energy-density energy storage and conversion applications, incorporating the fast transport of ceramic-like conductors with the superior flexibility of polymer electrolytes.
3. Multifactorial engineering of biomimetic membranes for batteries with multiple high-performance parameters

   https://doi.org/10.1038/s41467-021-27861-w  

   Wang, Mingqiang ; Emre, Ahmet E. ; Kim, Ji-Young ; Huang, Yiting ; Liu, Li ; Cecen, Volkan ; Huang, Yudong ; Kotov, Nicholas A. ( January 2022 , Nature Communications)

   Lithium–sulfur (Li–S) batteries have a high specific capacity, but lithium polysulfide (LPS) diffusion and lithium dendrite growth drastically reduce their cycle life. High discharge rates also necessitate their resilience to high temperature. Here we show that biomimetic self-assembled membranes from aramid nanofibers (ANFs) address these challenges. Replicating the fibrous structure of cartilage, multifactorial engineering of ion-selective mechanical, and thermal properties becomes possible. LPS adsorption on ANF surface creates a layer of negative charge on nanoscale pores blocking LPS transport. The batteries using cartilage-like bioinspired ANF membranes exhibited a close-to-theoretical-maximum capacity of 1268 mAh g⁻¹, up to 3500+ cycle life, and up to 3C discharge rates. Essential for safety, the high thermal resilience of ANFs enables operation at temperatures up to 80 °C. The simplicity of synthesis and recyclability of ANFs open the door for engineering high-performance materials for numerous energy technologies.
4. On the thermal and mechanical properties of Mg _0.2 Co _0.2 Ni _0.2 Cu _0.2 Zn _0.2 O across the high-entropy to entropy-stabilized transition

   https://doi.org/10.1063/5.0122775  

   Rost, Christina M. ; Schmuckler, Daniel L. ; Bumgardner, Clifton ; Bin Hoque, Md Shafkat ; Diercks, David R. ; Gaskins, John T. ; Maria, Jon-Paul ; Brennecka, Geoffrey L. ; Li, Xiadong ; Hopkins, Patrick E. ( December 2022 , APL Materials)

   As various property studies continue to emerge on high entropy and entropy-stabilized ceramics, we seek a further understanding of the property changes across the phase boundary between “high-entropy” and “entropy-stabilized” phases. The thermal and mechanical properties of bulk ceramic entropy stabilized oxide composition Mg 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 O are investigated across this critical transition temperature via the transient plane-source method, temperature-dependent x-ray diffraction, and nano-indentation. The thermal conductivity remains constant within uncertainty across the multi-to-single phase transition at a value of ≈2.5 W/mK, while the linear coefficient of thermal expansion increases nearly 24% from 10.8 to 14.1 × 10 −6 K −1 . Mechanical softening is also observed across the transition.
5. One-step fabrication of robust lithium ion battery separators by polymerization-induced phase separation

   https://doi.org/10.1039/D1TA10730E  

   Manly, Alexander J. ; Tenhaeff, Wyatt E. ( May 2022 , Journal of Materials Chemistry A)

   Conventional lithium ion battery separators are microporous polyolefin membranes that play a passive role in the electrochemical cell. Next generation separators should offer significant performance enhancements, while being fabricated through facile, low cost approaches with the ability to readily tune physicochemical properties. This study presents a single-step manufacturing technique based on UV-initiated polymerization-induced phase separation (PIPS), wherein microporous separators are fabricated from multifunctional monomers and ethylene carbonate (EC), which functions as both the pore-forming agent (porogen) and electrolyte component in the electrochemical cell. By controlling the ratio of the 1,4-butanediol diacrylate (BDDA) monomer to ethylene carbonate, monolithic microporous membranes are readily prepared with 25 μm thickness and pore sizes and porosities ranging from 6.8 to 22 nm and 15.4% to 38.5%, respectively. With 38.5% apparent porosity and an average pore size of 22 nm, the poly(1,4-butanediol diacrylate) (pBDDA) separator takes up 127% liquid electrolyte, resulting in an ionic conductivity of 1.98 mS cm −1 , which is greater than in conventional Celgard 2500. Lithium ion battery half cells consisting of LiNi 0.5 Mn 0.3 Co 0.2 O 2 cathodes and pBDDA separators were shown to undergo reversible charge/discharge cycling with an average discharge capacity of 142 mA h g −1more »and a capacity retention of 98.4% over 100 cycles – comparable to cells using state-of-the-art separators. Moreover, similar discharge capacities were achieved in rate performance tests due to the high ionic conductivity and electrolyte uptake of the film. The pBDDA separators were shown to be thermally stable to 374 °C, lack low temperature thermal transitions that can compromise cell safety, and exhibit no thermal shrinkage up to 150 °C.« less