An official website of the United States government
Abstract The diffusion pathways of Li‐ions as they traverse cathode structures in the course of insertion reactions underpin many questions fundamental to the functionality of Li‐ion batteries. Much current knowledge derives from computational models or the imaging of lithiation behavior at larger length scales; however, it remains difficult to experimentally image Li‐ion diffusion at the atomistic level. Here, by using topochemical Li‐ion insertion and extraction to induce single‐crystal‐to‐single‐crystal transformations in a tunnel‐structured V2O5polymorph, coupled with operando powder X‐ray diffraction, we leverage single‐crystal X‐ray diffraction to identify the sequence of lattice interstitial sites preferred by Li‐ions to high depths of discharge, and use electron density maps to create a snapshot of ion diffusion in a metastable phase. Our methods enable the atomistic imaging of Li‐ions in this cathode material in kinetic states and provide an experimentally validated angstrom‐level 3D picture of atomic pathways thus far only conjectured through DFT calculations.
more »
« less
This content will become publicly available on December 1, 2025
Operando real-space imaging of a structural phase transformation in the high-voltage electrode LixNi0.5Mn1.5O4
Abstract Discontinuous solid-solid phase transformations play a pivotal role in determining the properties of rechargeable battery electrodes. By leveraging operando Bragg Coherent Diffractive Imaging (BCDI), we investigate the discontinuous phase transformation in LixNi0.5Mn1.5O4within an operational Li metal coin cell. Throughout Li-intercalation, we directly observe the nucleation and growth of the Li-rich phase within the initially charged Li-poor phase in a 500 nm particle. Supported by the microelasticity model, the operando imaging unveils an evolution from a curved coherent to a planar semi-coherent interface driven by dislocation dynamics. Our data indicates negligible kinetic limitations from interface propagation impacting the transformation kinetics, even at a discharge rate of C/2 (80 mA/g). This study highlights BCDI’s capability to decode complex operando diffraction data, offering exciting opportunities to study nanoscale phase transformations with various stimuli.
more »
« less
- Award ID(s):
- 1944907
- PAR ID:
- 10575972
- Publisher / Repository:
- Springer Nature
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 15
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Sulfide solid‐state electrolytes have remarkable ionic conductivity and low mechanical stiffness but suffer from relatively narrow electrochemical and chemical stability with electrodes. Therefore, pairing sulfide electrolytes with the proper cathode is crucial in developing stable all‐solid‐state Li batteries (ASLBs). Herein, one type of thioantimonate ion conductor, Li6+xGexSb1−xS5I, with different compositions is systematically synthesized and studied, among these compositions, an outstanding ionic conductivity of 1.6 mS cm−1is achieved with Li6.6Ge0.6Sb0.4S5I. To improve the energy density and advance the interface compatibility, a metal sulfide FeS2cathode with a high theoretical capacity (894 mAh g−1) and excellent compatibility with sulfide electrolytes is coupled with Li6.6Ge0.6Sb0.4S5I in ASLBs without additional interface engineering. The structural stabilities of Li6.6Ge0.6Sb0.4S5I and FeS2during cycling are characterized by operando energy dispersive X‐ray diffraction, which allows rapid collection of structural data without redesigning or disassembling the sealed cells and risking contamination by air. The electrochemical stability is assessed, and a safe operating voltage window ranging from 0.7≈2.4 V (vs. In–Li) is confirmed. Due to the solid confinement in the ASLBs, the Fe0aggregation and polysulfides shuttle effects are well addressed. The ASLBs exhibit an outstanding initial capacity of 715 mAh g−1at C/10 and are stable for 220 cycles with a high capacity retention of 84.5% at room temperature.more » « less
-
Abstract Due to its outstanding safety and high energy density, all‐solid‐state lithium‐sulfur batteries (ASLSBs) are considered as a potential future energy storage technology. The electrochemical reaction pathway in ASLSBs with inorganic solid‐state electrolytes is different from Li‐S batteries with liquid electrolytes, but the mechanism remains unclear. By combining operando Raman spectroscopy and ex situ X‐ray absorption spectroscopy, we investigated the reaction mechanism of sulfur (S8) in ASLSBs. Our results revealed that no Li2S8,Li2S6,and Li2S4were formed, yet Li2S2was detected. Furthermore, first‐principles structural calculations were employed to disclose the formation energy of solid state Li2Sn(1≤n≤8), in which Li2S2was a metastable phase, consistent with experimental observations. Meanwhile, partial S8and Li2S2remained at the full lithiation stage, suggesting incomplete reaction due to sluggish reaction kinetics in ASLSBs.more » « less
-
Abstract All‐solid‐state Li‐metal batteries (ASLMBs) represent a significant breakthrough in the quest to overcome limitations associated with traditional Li‐ion batteries, particularly in energy density and safety aspects. However, widespread implementation is stymied due to a lack of profound understanding of the complex mechano‐electro‐chemical behavior of Li metal in the ASLMBs. Herein, operando neutron imaging and X‐ray computed tomography (XCT) are leveraged to nondestructively visualize Li behaviors within ASLMBs. This approach offers real‐time observations of Li evolutions, both pre‐ and post‐ occurrence of a “soft short”. The coordination of 2D neutron radiography and 3D neutron tomography enables charting of the terrain of Li metal deformation operando. Concurrently, XCT offers a 3D insight into the internal structure of the battery following a “soft short”. Despite the manifestation of a “soft short”, the persistence of Faradaic processes is observed. To study the elusive “soft short” , phase field modeling is coupled with electrochemistry and solid mechanics theory. The research unravels how external pressure curbs dendrite growth, potentially leading to dendrite fractures and thus uncovering the origins of both “soft” and “hard” shorts in ASLMBs. Furthermore, by harnessing finite element modeling, it dive deeper into the mechanical deformation and the fluidity of Li metal.more » « less
-
Abstract Lithium metal (Li0) solid‐state batteries encounter implementation challenges due to dendrite formation, side reactions, and movement of the electrode–electrolyte interface in cycling. Notably, voids and cracks formed during battery fabrication/operation are hot spots for failure. Here, a self‐healing, flowable yet solid electrolyte composed of mobile ceramic crystals embedded in a reconfigurable polymer network is reported. This electrolyte can auto‐repair voids and cracks through a two‐step self‐healing process that occurs at a fast rate of 5.6 µm h−1. A dynamical phase diagram is generated, showing the material can switch between liquid and solid forms in response to external strain rates. The flowability of the electrolyte allows it to accommodate the electrode volume change during Li0stripping. Simultaneously, the electrolyte maintains a solid form with high tensile strength (0.28 MPa), facilitating the regulation of mossy Li0deposition. The chemistries and kinetics are studied by operando synchrotron X‐ray and in situ transmission electron microscopy (TEM). Solid‐state NMR reveals a dual‐phase ion conduction pathway and rapid Li+diffusion through the stable polymer‐ceramic interphase. This designed electrolyte exhibits extended cycling life in Li0–Li0cells, reaching 12 000 h at 0.2 mA cm−2and 5000 h at 0.5 mA cm−2. Furthermore, owing to its high critical current density of 9 mA cm−2, the Li0–LiNi0.8Mn0.1Co0.1O2(NMC811) full cell demonstrates stable cycling at 5 mA cm−2for 1100 cycles, retaining 88% of its capacity, even under near‐zero stack pressure conditions.more » « less
