The discovery of novel materials with desired properties is essential to the advancements of energy-related technologies. Despite the rapid development of computational infrastructures and ...theoretical approaches, progress so far has been limited by the empirical and serial nature of experimental work. Fortunately, the situation is changing thanks to the maturation of theoretical tools such as density functional theory, high-throughput screening, crystal structure prediction, and emerging approaches based on machine learning. Together these recent innovations in computational chemistry, data informatics, and machine learning have acted as catalysts for revolutionizing material design and hopefully will lead to faster kinetics in the development of energy-related industries. In this report, recent advances in material discovery methods are reviewed for energy devices. Three paradigms based on empiricism-driven experiments, database-driven high-throughput screening, and data informatics-driven machine learning are discussed critically. Key methodological advancements involved are reviewed including high-throughput screening, crystal structure prediction, and generative models for target material design. Their applications in energy-related devices such as batteries, catalysts, and photovoltaics are selectively showcased.
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In this work, we adopt first-principles calculations and ab-initio molecular dynamics simulations to investigate the potential of borophene as an anode material for lithium-ion batteries. It is found ...that borophene has an adsorption energy to lithium atom of −1.12eV, which is large enough to ensure a good lithium-borophene stability during the lithiation process. The fully lithiated phase of borophene is Li0.75B, corresponding to a theoretical specific capacity of 1860mAhg−1, which is about 4 times larger than that of the commercial graphite anode (372mAhg−1). More excitingly, it is found that the energy barrier along the furrow of corrugated borophene is only 2.6meV, which is much lower than those of other widely investigated anode materials such as phosphorene (80meV) and Ti3C2 (70meV). The finding suggests that lithium diffusion on borophene can be extremely fast. In the meantime, a strong directional anisotropy is observed for lithium diffusion, with a 325.1meV barrier perpendicular to the furrow of borophene. This phenomenon is further proved by ab-initio molecular dynamics simulations at 300K and the result shows the lithium atom can freely drift along the furrow, but seldom jumps to the neighboring furrows. Finally, borophene is found to exhibit metallic characteristics during the whole lithiation process, indicating that the material has an excellent electronic conductivity. The findings reported in this work suggest that borophene, as an anode material for lithium-ion batteries, has potential to drastically boost batteries' energy density and power density.
In this work, we adopt first-principles calculations and ab-initio molecular dynamics simulations to investigate the potential of borophene as an anode material for lithium-ion batteries. It is found that: i) the theoretical specific capacity of borophene is 1860mAhg−1, a figure which is 4 times higher than that of graphite; ii) the lithium diffusion is extremely fast with an only 2.6meV energy barrier along the furrow of corrugated borophene; iii) borophene exhibits metallic characteristics during the whole lithiation process. The findings suggest that borophene is a promising anode material for lithium-ion batteries that might revolutionarily boost batteries' energy density and power density.
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•A new 2D material, borophene, is found to be a promising anode material for LIBs.•The fully lithiated borophene has a high specific capacity of 1860mAhg−1.•The Li diffusion on borophene is extremely fast with a 2.6meV energy barrier.•Borophene exhibits metallic characteristics during the whole lithiation process.
Abstract
Understanding Li diffusion in solid conductors is essential for the next generation Li batteries. Here we show that density-based clustering of the trajectories computed using molecular ...dynamics simulations helps elucidate the Li diffusion mechanism within the Li
7
La
3
Zr
2
O
12
(LLZO) crystal lattice. This unsupervised learning method recognizes lattice sites, is able to give the site type, and can identify Li hopping events. Results show that, while the cubic LLZO has a much higher hopping rate compared to its tetragonal counterpart, most of the Li hops in the cubic LLZO do not contribute to the diffusivity due to the dominance of back-and-forth type jumps. The hopping analysis and local Li configuration statistics give evidence that Li diffusivity in cubic LLZO is limited by the low vacancy concentration. The hopping statistics also shows uncorrelated Poisson-like diffusion for Li in the cubic LLZO, and correlated diffusion for Li in the tetragonal LLZO in the temporal scale. Further analysis of the spatio-temporal correlation using site-to-site mutual information confirms the weak site dependence of Li diffusion in the cubic LLZO as the origin for the uncorrelated diffusion. This work puts forward a perspective on combining machine learning and information theory to interpret results of molecular dynamics simulations.
Abstract
Exploiting solid electrolyte (SE) materials with high ionic conductivity, good interfacial compatibility, and conformal contact with electrodes is essential for solid-state sodium metal ...batteries (SSBs). Here we report a crystalline Na
5
SmSi
4
O
12
SE which features high room-temperature ionic conductivity of 2.9 × 10
−3
S cm
−1
and a low activation energy of 0.15 eV. All-solid-state symmetric cell with Na
5
SmSi
4
O
12
delivers excellent cycling life over 800 h at 0.15 mA h cm
−2
and a high critical current density of 1.4 mA cm
−2
. Such excellent electrochemical performance is attributed to an electrochemically induced in-situ crystalline-to-amorphous (CTA) transformation propagating from the interface to the bulk during repeated deposition and stripping of sodium, which leads to faster ionic transport and superior interfacial properties. Impressively, the Na|Na
5
SmSi
4
O
12
|Na
3
V
2
(PO
4
)
3
sodium metal batteries achieve a remarkable cycling performance over 4000 cycles (6 months) with no capacity loss. These results not only identify Na
5
SmSi
4
O
12
as a promising SE but also emphasize the potential of the CTA transition as a promising mechanism towards long-lasting SSBs.
The discovery of 250-kelvin superconducting lanthanum polyhydride under high pressure marked a significant advance toward the realization of a room-temperature superconductor. X-ray diffraction (XRD) ...studies reveal a nonstoichiometric LaH
or LaH
polyhydride responsible for the superconductivity, which in the literature is commonly treated as LaH
without accounting for stoichiometric defects. Here, we discover significant nuclear quantum effects (NQE) in this polyhydride, and demonstrate that a minor amount of stoichiometric defects will cause quantum proton diffusion in the otherwise rigid lanthanum lattice in the ground state. The diffusion coefficient reaches ~10
cm
/s in LaH
at 150 gigapascals and 240 kelvin, approaching the upper bound value of interstitial hydrides at comparable temperatures. A puzzling phenomenon observed in previous experiments, the positive pressure dependence of the superconducting critical temperature T
below 150 gigapascals, is explained by a modulation of the electronic structure due to a premature distortion of the hydrogen lattice in this quantum fluxional structure upon decompression, and resulting changes of the electron-phonon coupling. This finding suggests the coexistence of the quantum proton fluxion and hydrogen-induced superconductivity in this lanthanum polyhydride, and leads to an understanding of the structural nature and superconductivity of nonstoichiomectric hydrogen-rich materials.
The choice of cathode material in Li-ion batteries underpins their overall performance. Discovering new cathode materials is a slow process, and all major commercial cathode materials are still based ...on those identified in the 1990s. Discovery of materials using high-throughput calculations has attracted great research interest; however, reliance on databases of existing materials begs the question of whether these approaches are applicable for finding truly novel materials. In this work, we demonstrate that ab initio random structure searching (AIRSS), a first-principles structure prediction method that does not rely on any pre-existing data, can locate low energy structures of complex cathode materials efficiently based only on chemical composition. We use AIRSS to explore three Fe-containing polyanion compounds as low-cost cathodes. Using known quaternary LiFePO4 and quinary LiFeSO4F cathodes as examples, we easily reproduce the known polymorphs, in addition to predicting other, hitherto unknown, low energy polymorphs and even finding a new polymorph of LiFeSO4F that is more stable than the known ones. We then explore the phase space for Fe-containing fluoroxalates, predicting a range of redox-active phases that are yet to be experimentally synthesized, demonstrating the suitability of AIRSS as a tool for accelerating the discovery of novel cathode materials.
Carbon dioxide capture is essential to achieve net-zero emissions. A hurdle to the design of improved capture materials is the lack of adequate tools to characterise how CO
adsorbs. Solid-state ...nuclear magnetic resonance (NMR) spectroscopy is a promising probe of CO
capture, but it remains challenging to distinguish different adsorption products. Here we perform a comprehensive computational investigation of 22 amine-functionalised metal-organic frameworks and discover that
O NMR is a powerful probe of CO
capture chemistry that provides excellent differentiation of ammonium carbamate and carbamic acid species. The computational findings are supported by
O NMR experiments on a series of CO
-loaded frameworks that clearly identify ammonium carbamate chain formation and provide evidence for a mixed carbamic acid - ammonium carbamate adsorption mode. We further find that carbamic acid formation is more prevalent in this materials class than previously believed. Finally, we show that our methods are readily applicable to other adsorbents, and find support for ammonium carbamate formation in amine-grafted silicas. Our work paves the way for investigations of carbon capture chemistry that can enable materials design.
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