Graphite interfaces are an important part of the anode in lithium-ion batteries(LIBs),significantly influencing Li intercalation kinetics.Graphite anodes adopt different stacking sequences depending on the concentrati...Graphite interfaces are an important part of the anode in lithium-ion batteries(LIBs),significantly influencing Li intercalation kinetics.Graphite anodes adopt different stacking sequences depending on the concentration of the intercalated Li ions.In this work,we performed first-principles calculations to comprehensively address the energetics and dynamics of Li intercalation and Li vacancy diffusion near the no n-basal edges of graphite,namely the armchair and zigzag-edges,at high Li concentration.We find that surface effects persist in stage-Ⅱ that bind Li strongly at the edge sites.However,the pronounced effect previously identified at the zigzag edge of pristine graphite is reduced in LiC_(12),penetrating only to the subsurface site,and eventually disappearing in LiC_(6).Consequently,the distinctive surface state at the zigzag edge significantly impacts and restrains the charging rate at the initial lithiation of graphite anodes,whilst diminishes with an increasing degree of lithiation.Longer diffusion time for Li hopping to the bulk site from either the zigzag edge or the armchair edge in LiC_(6) was observed during high state of charge due to charge repulsion.Effectively controlling Li occupation and diffusion kinetics at this stage is also crucial for enhancing the charge rate.展开更多
Alloying is an established strategy to tune the properties of bulk compounds for desired applications.With the advent of nanotechnology,the same strategy can be applied to 2D materials for technological applications,l...Alloying is an established strategy to tune the properties of bulk compounds for desired applications.With the advent of nanotechnology,the same strategy can be applied to 2D materials for technological applications,like single-layer transistors and solid lubricants.Here we present a systematic analysis of the phase behaviour of substitutional 2D alloys in the Transition Metal Disulfides(TMD)family.The phase behaviour is quantified in terms of a metastability metric and benchmarked against many-body expansion of the energy landscape.We show how the metastability metric can be directly used as starting point for setting up rational search strategies in phase space,thus allowing for targeted further computational prediction and analysis of properties.The results presented here also constitute a useful guideline for synthesis of TMDs binary alloys via a range of synthesis techniques.展开更多
基金financial support from the National Natural Science Foundation of China(52203303)the International Partnership Program of the Chinese Academy of Sciences(321GJHZ2023189FN)+2 种基金the Natural Science Foundation of Guangdong Province(2022A1515010076)the Shenzhen Science and Technology Program(SGDX20211123151002003)the Shenzhen International Cooperation Program(GJHZ20220913142812025)。
文摘Graphite interfaces are an important part of the anode in lithium-ion batteries(LIBs),significantly influencing Li intercalation kinetics.Graphite anodes adopt different stacking sequences depending on the concentration of the intercalated Li ions.In this work,we performed first-principles calculations to comprehensively address the energetics and dynamics of Li intercalation and Li vacancy diffusion near the no n-basal edges of graphite,namely the armchair and zigzag-edges,at high Li concentration.We find that surface effects persist in stage-Ⅱ that bind Li strongly at the edge sites.However,the pronounced effect previously identified at the zigzag edge of pristine graphite is reduced in LiC_(12),penetrating only to the subsurface site,and eventually disappearing in LiC_(6).Consequently,the distinctive surface state at the zigzag edge significantly impacts and restrains the charging rate at the initial lithiation of graphite anodes,whilst diminishes with an increasing degree of lithiation.Longer diffusion time for Li hopping to the bulk site from either the zigzag edge or the armchair edge in LiC_(6) was observed during high state of charge due to charge repulsion.Effectively controlling Li occupation and diffusion kinetics at this stage is also crucial for enhancing the charge rate.
基金This project has received funding from the European Union’s Horizon2020 research and innovation programme under grant agreement No.721642:SOLUTIONTP acknowledges support of the project CAAS CZ.02.1.010.00.016_0190000778.
文摘Alloying is an established strategy to tune the properties of bulk compounds for desired applications.With the advent of nanotechnology,the same strategy can be applied to 2D materials for technological applications,like single-layer transistors and solid lubricants.Here we present a systematic analysis of the phase behaviour of substitutional 2D alloys in the Transition Metal Disulfides(TMD)family.The phase behaviour is quantified in terms of a metastability metric and benchmarked against many-body expansion of the energy landscape.We show how the metastability metric can be directly used as starting point for setting up rational search strategies in phase space,thus allowing for targeted further computational prediction and analysis of properties.The results presented here also constitute a useful guideline for synthesis of TMDs binary alloys via a range of synthesis techniques.
