Engineering topics
Publications and source records attributed to Li, Linsen.
The present disclosure is generally related to separators for use in lithium metal batteries, and associated systems and products. Certain embodiments are related to separators that form or are repaired when an electrode is held at a voltage. In some embodiments, an electrochemical cell may comprise an electrolyte that comprises a precursor for the separator.
Color centers in diamond play a central role in the development of quantum photonic technologies, and their importance is only expected to grow in the near future. For many quantum applications, high collection efficiency from individual emitters is required, but the refractive index mismatch between diamond and air limits the optimal collection efficiency with conventional diamond device geometries. While different out-coupling methods with near-unity efficiency exist, many have yet to be realized due to current limitations in nanofabrication methods, especially for mechanically hard materials like diamond. Here, we leverage electron-beam-induced etching to modify Sn-implanted diamond quantum microchiplets containing integrated waveguides with a width and thickness of 280 nm and 200 nm, respectively. This approach allows for simultaneous high-resolution imaging and modification of the host matrix with an open geometry and direct writing. When coupled with the cathodoluminescence signal generated from the electron–emitter interactions, we can monitor the enhancement of the quantum emitters in real-time with nanoscale spatial resolution. The operando cathodoluminescence measurement and fabrication around single photon emitters demonstrated here provide a new foundation for the potential control of emitter–cavity interactions in integrated quantum photonics.
Color centers (CCs) in nanostructured diamond are promising for optically linked quantum technologies. Scaling to useful applications motivates architectures meeting the following criteria: C1 individual optical addressing of spin qubits; C2 frequency tuning of spin-dependent optical transitions; C3 coherent spin control; C4 active photon routing; C5 scalable manufacturability; and C6 low on-chip power dissipation for cryogenic operations. Here, we introduce an architecture that simultaneously achieves C1–C6. We realize piezoelectric strain control of diamond waveguide-coupled tin vacancy centers with ultralow power dissipation necessary. The DC response of our device allows emitter transition tuning by over 20 GHz, combined with low-power AC control. We show acoustic spin resonance of integrated tin vacancy spins and estimate single-phonon coupling rates over 1 kHz in the resolved sideband regime. Combined with high-speed optical routing, our work opens a path to scalable single-qubit control with optically mediated entangling gates.
A central goal in many quantum information processing applications is a network of quantum memories that can be entangled with each other while being individually controlled and measured with high fidelity. This goal has motivated the development of programmable photonic integrated circuits (PICs) with integrated spin quantum memories using diamond color center spin-photon interfaces. However, this approach introduces a challenge into the microwave control of individual spins within closely packed registers. Here, we present a quantum memory-integrated photonics platform capable of (i) the integration of multiple diamond color center spins into a cryogenically compatible, high-speed programmable PIC platform, (ii) selective manipulation of individual spin qubits addressed via tunable magnetic field gradients, and (iii) simultaneous control of qubits using numerically optimized microwave pulse shaping. The combination of localized optical control, enabled by the PIC platform, together with selective spin manipulation opens the path to scalable quantum networks on intrachip and interchip platforms.
P2-Na 0.67 Ni 0.33 Mn 0.67 O 2 represents a promising cathode for Na-ion batteries, but it suffers from severe structural degradation upon storing in a humid atmosphere and cycling at a high cutoff voltage. Here we propose an in situ construction to achieve simultaneous material synthesis and Mg/Sn cosubstitution of Na 0.67 Ni 0.33 Mn 0.67 O 2 via one-pot solid-state sintering. Here, the materials exhibit superior structural reversibility and moisture insensitivity. In-operando XRD reveals an essential correlation between cycling stability and phase reversibility, whereas Mg substitution suppressed the P2–O2 phase transition by forming a new Z phase, and Mg/Sn cosubstitution enhanced the P2–Z transition reversibility benefiting from strong Sn–O bonds. DFT calculations disclosed high chemical tolerance to moisture, as the adsorption energy to H 2 O was lower than that of the pure Na 0.67 Ni 0.33 Mn 0.67 O 2 . A representative Na 0.67 Ni 0.23 Mg 0.1 Mn 0.65 Sn 0.02 O 2 cathode exhibits high reversible capacities of 123 mAh g –1 (10 mA g –1 ), 110 mAh g –1 (200 mA g –1 ), and 100 mAh g –1 (500 mA g –1 ) and a high capacity retention of 80% (500 mA g –1 , 500 cycles).
Lithium-ion battery (LIB) is a broadly adopted technology for energy storage. With increasing demands to improve the rate capability, cyclability, energy density, safety, and cost efficiency, it is crucial to establish an in-depth understanding of the detailed structural evolution and cell-degradation mechanisms during battery operation. Here, we present a laboratory-based high-resolution and high-throughput X-ray micro–computed laminography approach, which is capable of in situ visualizing of an industry-relevant lithium-ion (Li-ion) pouch cell with superior detection fidelity, resolution, and reliability. This technique enables imaging of the pouch cell at a spatial resolution of 0.5 μm in a laboratory system and permits the identification of submicron features within cathode and anode electrodes. We also demonstrate direct visualization of the lithium plating in the imaged pouch cell, which is an important phenomenon relevant to battery fast charging and low-temperature cycling. Our development presents an avenue toward a thorough understanding of the correlation among multiscale structures, chemomechanical degradation, and electrochemical behavior of industry-scale battery pouch cells.
The present invention is generally related to separators for use in lithium metal batteries, and associated systems and products. Certain embodiments are related to separators that form or are repaired when an electrode is held at a voltage. In some embodiments, an electrochemical cell may comprise an electrolyte that comprises a precursor for the separator.
Aqueous Zn-ion battery is a promising technology for electrochemical energy storage. The formation of Zn dendrites, however, can jeopardize the cell cycle life and thus, hinders the industrial adoption of this technology. A fundamental understanding of the kinetic mechanisms is crucial for improving the Zn-ion battery. Here, in situ and operando X-ray microscopy methods are utilized to visualize the Zn plating and stripping behaviors under different electrochemical conditions. It is demonstrated that the substrate curvature, local morphology, electrochemical protocols, and the surface chemistry can collectively affect the Zn plating behavior. Furthermore, these results provide new insights for developing the next-generation dendrite-free and long-span aqueous Zn-ion battery.
As an important battery cathode material, reaction distribution in lithium iron phosphate (LiFePO4) has been extensively studied in dispersed particle systems, but remains poorly understood for mesoscopic agglomerates (or secondary particles) that are used in most commercial batteries. Herein, we apply three-dimensional X-ray spectroscopic imaging to characterize the two-phase structure in LiFePO4 secondary particles during electrochemical cycling. (De)lithiated domains are found to not form the commonly assumed core-shell structure but develop highly anisotropic filamentary morphology that is rate independent and symmetric between charging and discharging. Phase-field simulations elucidate that the observed 1D phase growth behavior is not caused by the 1D lithium diffusivity of LiFePO4 but the elastic interaction between primary particles, which gives rise to stronger reaction heterogeneity than dispersed nanoparticles. As a result, uniform lithium (de)intercalation does not occur on the secondary particle surface even at high cycling rates.
The electrification revolution in the automobile and other industries demands annual production capacity of batteries of at least 10 2 GWh, which presents a twofold challenge: supply of key materials such as cobalt and nickel and recycling when batteries are retired from use. Pyrometallurgical and hydrometallurgical recycling are currently used in industry but suffer from complexity, high costs, and secondary pollution. Here we report a molten-salt-based method for direct recycling (MSDR) that is environmentally benign and creates value on the basis of a techno-economic analysis using real-world data and price information. We also experimentally demonstrate the feasibility of MSDR by upcycling a low-nickel polycrystalline LiNi 0.5 Mn 0.3 Co 0.2 O 2 (NMC) cathode material into Ni-rich (Ni > 65%) single-crystal NMCs with increased energy density (>10% increase) and outstanding electrochemical performance (>94% capacity retention after 500 cycles). This work may open opportunities for closed-loop recycling of electric vehicle batteries and manufacturing of next-generation NMC cathode materials.
We report P2-type sodium layered oxide cathode (Na 2/3 Ni 1/3 Mn 2/3 O 2 , P2-NNMO) has attracted great attention as a promising cathode material for sodium ion batteries because of its high specific capacity. However, this material suffers from a rapid capacity fade during high-voltage cycling. Several mechanisms have been proposed to explain the capacity fade, including intragranular fracture caused by the P2-O2 phase transion, surface structural change, and irreversible lattice oxygen release. Here we systematically investigated the morphological, structural, and chemical changes of P2-NNMO during high-voltage cycling using a variety of characterization techniques. It was found that the lattice distortion and crystal-plane buckling induced by the P2-O2 phase transition slowed down the Na-ion transport in the bulk and hindered the extraction of the Na ions. The sluggish kinetics was the main reason in reducing the accessible capacity while other interfacial degradation mechanisms played minor roles. Our results not only enabled a more complete understanding of the capacity-fading mechanism of P2-NNMO but also revealed the underlying correlations between lattice doping and the moderately improved cycle performance.
The present disclosure is generally related to separators for use in lithium metal batteries, and associated systems and products. Certain embodiments are related to separators that form or are repaired when an electrode is held at a voltage. In some embodiments, an electrochemical cell may comprise an electrolyte that comprises a precursor for the separator.
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Incorporation of foreign elements into the cathode material is broadly adopted by both academia and industry to improve the battery performance. The lack of an in-depth understanding for the underlying mechanism, however, makes it a largely try-and-error process with unsatisfactory efficiency and effectiveness. This is particularly true for the electrochemical reaction kinetics that is heterogeneous over a broad range of length scales and is determined collectively by the cathode’s electronic structure, lattice configuration, and micro-morphology. In this work, we unveiled a facet-dependent dopant segregation effect in Zr-modified single-crystal LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode. By forming kinetically favored corners on the cathode particles, the presence of a trace amount of Zr critically modulates the mesoscale reaction kinetics. Our findings suggest that a delicately controlled dopant distribution is a viable strategy for designing the next-generation battery cathode with superior structural and chemical robustness.
Single-crystal lithium-nickel-manganese-cobalt-oxide (SC-NMC) has recently emerged as a promising battery cathode material due to its outstanding cycle performance and mechanical stability over the tradional polycrystalline NMC. It is favorable to further increase the grain size of SC-NMC particles to achieve a higher volumetric energy density and minimize surface-related degradations. However, the preparation of large-size yet high performance SC-NMC particles faces a challenge in choosing a suitable temperature for sintering. High temperature promotes grain growth but induces cation mixing that negatively impacts the electrochemical performance. Here we report a temperature-swing sintering (TSS) strategy with two isothermal stages that fulfils the needs for grain growth and structural ordering sequentially. A high-temperature sintering is first used for a short period of time to increase grain size and then the reaction temperature is lowered and kept constant for a longer period of time to improve structural ordering and complete the lithiation process. SC-LiNi 0.6 Mn 0.2 Co 0.2 O 2 materials prepared via TSS exhibit large grain size (~4 μm), a low degree of cation mixing (~0.9%), and outperform the control samples prepared by the conventional sintering method. Furthermore, this work highlights the importance of understanding the process-structure-property relationships and may guide the synthesis of other SC Ni-rich cathode materials.
The degradation of nickel-rich cathode materials for lithium-ion batteries upon prolonged electrochemical cycling features a complicated interplay among electronic structure, lattice configuration, and micro-morphology. The underlying mechanism for such an entanglement of different material properties at nano- to mesoscales is fundamental to the battery performance but not well-understood yet. Here we investigate the correlation between the local redox reaction and lattice mismatch through a nano-resolution synchrotron spectro-microscopy study of LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM 811) cathode particles. With assistance from a machine-learning-based data classification method, we identify local regions that demonstrate a strain–redox decoupling effect, which can be attributed to different side reactions. Overall, our results highlight the mesoscale reaction heterogeneity in the battery cathode and suggest that particle structure engineering could be a viable approach to mitigate the chemomechanical degradation of cathode materials.
Significance It is possible to nearly double the energy density of existing lithium-ion batteries by using lithium metal anodes. However, it has been known for decades that the lithium dendrites and mossy lithium formed during charging (electrodeposition) limit the cycle life of the batteries. It is important to change the growth behavior of lithium metal, which is closely related to the properties of the solid–electrolyte interface (SEI) formed via spontaneous reactions between the lithium metal and the electrolyte. In this experimental-modeling integrated study, we reveal the design principles of the SEI that facilitates the dendrite-free and dense deposition of lithium and demonstrate one of the best cycling performances of lithium metal anode to date under practically relevant conditions.