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Addressing the Voltage Induced Instability Problem of Perovskite Semiconductor Detectors
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Dicarbonyl Electrolyte for High-Voltage Lithium Metal Batteries: Importance of the Entropy of Solvation in Bidentate Solvent
An electrolyte system based on dicarbonyl solvents has been proposed and implemented in lithium metal batteries (LMBs). Among several dicarbonyl solvents explored, dimethyl dicarbonate (DMDC) emerged as the most promising electrolyte candidate. Interestingly, despite the structural similarities between DMDC and its monocarbonyl counterpart DMC, the DMDC electrolyte exhibits higher solvent coordination, even at the same lithium-to-carbonyl ratio. Further, this leads to the formation of a more robust solid-electrolyte interphase and enhances the anodic stability of the electrolyte. Notably, in various electrolyte systems, the solvation energy is typically enthalpy-driven. However, the bidentate nature of DMDC introduces a significant role for the entropy of solvation because the Li + -DMDC complexes release fewer free molecules. With the addition of non-solvating co-solvent 1,1,2,2-tetrafluoro-ethyl 2,2,3,3-tetrafluoro-propyl ether (TTE), which reduces the viscosity of the electrolyte, the DMDC-TTE system enables remarkably stable cycling of the lithium anode by manipulating the entropy of solvation. This introduces a new strategy for tailoring functional electrolyte systems.
Importance of High Valence Element Nb in Ni-Rich Layered Cathodes for High-Voltage Lithium-Metal Batteries
Ni-rich layered cathode materials have attracted extensive attention due to their higher energy density and technological maturity in commercialization. As the nickel content is raised, especially surpassing 80%, the increased energy density comes with the tradeoff of diminished thermal stability and increased electrochemical structural instability of the cathode. Compared with Co, Al, B, and Ta, the introduction of high valence element Nb significantly improved the electrochemical cycling, delivering a capacity of 202 mAh/g, corresponding to a capacity retention of 92% after 200 cycles tested at 45 °C. Further, the ex situ differential scanning calorimetry and in situ isothermal microcalorimetry demonstrate that the Nb-modified cathode has the potential to enhance the safety of ultrahigh nickel (Ni) NMCs and displays remarkable resilience to extensive cycling by inhibiting high-temperature decomposition reactions and exhibiting a lower heat flow during electrochemical cycling.
Long Period Voltage Oscillations Associated with Reaction Changes between CO 2 Reduction and H 2 Formation in Zero-Gap-Type CO 2 Electrochemical Reactor
Not Available
Voltage Control of Magnetism above Room Temperature in Epitaxial SrCo[subscript 1-x]Fe[subscript x]O[subscript 3;#8722;delta]
Abstract not provided
Role of Surface Acidity in the Surface Stabilization of the High-Voltage Cathode LiNi 0.6 Mn 0.2 Co 0.2 O 2
Not Available
Scalable Spray-On Fabrication Approach for Voltage-Tunable Thermal Emissivity Surfaces
Not Available
In situ inorganic conductive network formation in high-voltage single-crystal Ni-rich cathodes
High nickel content in LiNi x Co y Mn z O 2 (NCM, x ≥ 0.8, x + y + z = 1) layered cathode material allows high specific energy density in lithium-ion batteries (LIBs). However, Ni-rich NCM cathodes suffer from performance degradation, mechanical and structural instability upon prolonged cell cycling. Although the use of single-crystal Ni-rich NCM can mitigate these drawbacks, the ion-diffusion in large single-crystal particles hamper its rate capability. Herein, we report a strategy to construct an in situ Li 1.4 Y 0.4 Ti 1.6 (PO 4 ) 3 (LYTP) ion/electron conductive network which interconnects single-crystal LiNi 0.88 Co 0.09 Mn 0.03 O 2 (SC-NCM88) particles. The LYTP network facilitates the lithium-ion transport between SC-NCM88 particles, mitigates mechanical instability and prevents detrimental crystalline phase transformation. When used in combination with a Li metal anode, the LYTP-containing SC-NCM88-based cathode enables a coin cell capacity of 130 mAh g -1 after 500 cycles at 5 C rate in the 2.75-4.4 V range at 25 °C. Tests in Li-ion pouch cell configuration (i.e., graphite used as negative electrode active material) demonstrate capacity retention of 85% after 1000 cycles at 0.5 C in the 2.75-4.4 V range at 25 °C for the LYTP-containing SC-NCM88-based positive electrode.
A fluorinated cation introduces new interphasial chemistries to enable high-voltage lithium metal batteries
Abstract Fluorides have been identified as a key ingredient in interphases supporting aggressive battery chemistries. While the precursor for these fluorides must be pre-stored in electrolyte components and only delivered at extreme potentials, the chemical source of fluorine so far has been confined to either negatively-charge anions or fluorinated molecules, whose presence in the inner-Helmholtz layer of electrodes, and consequently their contribution to the interphasial chemistry, is restricted. To pre-store fluorine source on positive-charged species, here we show a cation that carries fluorine in its structure is synthesized and its contribution to interphasial chemistry is explored for the very first time. An electrolyte carrying fluorine in both cation and anion brings unprecedented interphasial chemistries that translate into superior battery performance of a lithium-metal battery, including high Coulombic efficiency of up to 99.98%, and Li 0 -dendrite prevention for 900 hours. The significance of this fluorinated cation undoubtedly extends to other advanced battery systems beyond lithium, all of which universally require kinetic protection of highly fluorinated interphases.