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Abstract A rapid transition in the energy infrastructure is crucial when irreversible damages are happening quickly in the next decade due to global climate change. It is believed that a practical strategy for decarbonization would be 8 h of lithium‐ion battery (LIB) electrical energy storage paired with wind/solar energy generation, and using existing fossil fuels facilities as backup. To reach the hundred terawatt‐hour scale LIB storage, it is argued that the key challenges are fire safety and recycling, instead of capital cost, battery cycle life, or mining/manufacturing challenges. A short overview of the ongoing innovations in these two directions is provided. 

Abstract All‐solid‐state batteries with metallic lithium (Li_BCC) anode and solid electrolyte (SE) are under active development. However, an unstable SE/Li_BCCinterface due to electrochemical and mechanical instabilities hinders their operation. Herein, an ultra‐thin nanoporous mixed ionic and electronic conductor (MIEC) interlayer (≈3.25 µm), which regulates Li_BCCdeposition and stripping, serving as a 3D scaffold for Li⁰ad‐atom formation, Li_BCCnucleation, and long‐range transport of ions and electrons at SE/Li_BCCinterface is demonstrated. Consisting of lithium silicide and carbon nanotubes, the MIEC interlayer is thermodynamically stable against Li_BCCand highly lithiophilic. Moreover, its nanopores (<100 nm) confine the deposited Li_BCCto the size regime where Li_BCCexhibits “smaller is much softer” size‐dependent plasticity governed by diffusive deformation mechanisms. The Li_BCCthus remains soft enough not to mechanically penetrate SE in contact. Upon further plating, Li_BCCgrows in between the current collector and the MIEC interlayer, not directly contacting the SE. As a result, a full‐cell having Li_3.75Si‐CNT/Li_BCCfoil as an anode and LiNi_0.8Co_0.1Mn_0.1O₂as a cathode displays a high specific capacity of 207.8 mAh g⁻¹, 92.0% initial Coulombic efficiency, 88.9% capacity retention after 200 cycles (Coulombic efficiency reaches 99.9% after tens of cycles), and excellent rate capability (76% at 5 C). 

Abstract Designing stable Li metal and supporting solid structures (SSS) is of fundamental importance in rechargeable Li‐metal batteries. Yet, the stripping kinetics of Li metal and its mechanical effect on the supporting solids (including solid electrolyte interface) remain mysterious to date. Here, through nanoscale in situ observations of a solid‐state Li‐metal battery in an electron microscope, two distinct cavitation‐mediated Li stripping modes controlled by the ratio of the SSS thickness (t) to the Li deposit's radius (r) are discovered. A quantitative criterion is established to understand the damage tolerance of SSS on the Li‐metal stripping pathways. For mechanically unstable SSS (t/r < 0.21), the stripping proceeds via tension‐induced multisite cavitation accompanied by severe SSS buckling and necking, ultimately leading to Li “trapping” or “dead Li” formation; for mechanically stable SSS (t/r > 0.21), the Li metal undergoes nearly planar stripping from the root via single cavitation, showing negligible buckling. This work proves the existence of an electronically conductive precursor film coated on the interior of solid electrolytes that however can be mechanically damaged, and it is of potential importance to the design of delicate Li‐metal supporting structures to high‐performance solid‐state Li‐metal batteries. 

Abstract The 3D nanocomposite structure of plated lithium (Li_Metal) and solid electrolyte interphases (SEI), including a polymer‐rich surficial passivation layer (SEI exoskeleton) and inorganic SEI “fossils” buried inside amorphous Li matrix, is resolved using cryogenic transmission electron microscopy. With ether‐based DOLDME‐LiTFSI electrolyte, LiF and Li₂O nanocrystals are formed and embedded in a thin but tough amorphous polymer in the SEI exoskeleton. The fast Li‐stripping directions are along or , which produces eight exposed {111} planes at halfway charging. Full Li stripping produces completely sagging, empty SEI husks that can sustain large bending and buckling, with the smallest bending radius of curvature observed approaching tens of nanometers without apparent damage. In the 2nd round of Li plating, a thin Li_BCCsheet first nucleates at the current collector, extends to the top end of the deflated SEI husk, and then expands its thickness. The apparent zero wetting angle between Li_BCCand the SEI interior means that the heterogeneous nucleation energy barrier is zero. Due to its complete‐wetting property and chemo‐mechanical stability, the SEI largely prevents further reactions between the Li metal and the electrolyte, which explains the superior performance of Li‐metal batteries with ether‐based electrolytes. However, uneven refilling of the SEI husks results in dendrite protrusions and some new SEI formation during the 2nd plating. A strategy to form bigger SEI capsules during the initial cycle with higher energy density than the following cycles enables further enhanced Coulombic efficiency to above 99%. 

Abstract The solid electrolyte interphase (SEI) dictates the cycling stability of lithium‐metal batteries. Here, direct atomic imaging of the SEI's phase components and their spatial arrangement is achieved, using ultralow‐dosage cryogenic transmission electron microscopy. The results show that, surprisingly, a lot of the deposited Li metal has amorphous atomic structure, likely due to carbon and oxygen impurities, and that crystalline lithium carbonate is not stable and readily decomposes when contacting the lithium metal. Lithium carbonate distributed in the outer SEI also continuously reacts with the electrolyte to produce gas, resulting in a dynamically evolving and porous SEI. Sulfur‐containing additives cause the SEI to preferentially generate Li₂SO₄and overlithiated lithium sulfate and lithium oxide, which encapsulate lithium carbonate in the middle, limiting SEI thickening and enhancing battery life by a factor of ten. The spatial mapping of the SEI gradient amorphous (polymeric → inorganic → metallic) and crystalline phase components provides guidance for designing electrolyte additives. 

High-voltage lithium-metal batteries (LMBs) with LiCoO 2 (LCO) as the cathode have high volumetric and gravimetric energy densities. However, it remains a challenge for stable cycling of LCO >4.5 V Li . Here we demonstrate that a rationally designed sulfonamide-based electrolyte can greatly improve the cycling stability at high voltages up to 4.7 V Li by stabilizing the electrode–electrolyte interfaces (EEIs) on both the Li-metal anode (LMA) and high-voltage LCO cathode. With the sulfonamide-based electrolyte, commercial LCO cathodes retain 89% and 85% of their capacities after 200 and 100 cycles under high charging voltages of 4.55 V Li and 4.6 V Li , respectively, significantly outperforming traditional carbonate-based electrolytes. The surface degradation, impedance growth, and detrimental side reactions in terms of gas evolution and Co dissolution are well suppressed. Our work demonstrates a promising strategy for designing new electrolytes to realize high-energy Li||LCO batteries.