Sophisticated efficient electrocatalysts are essential to rectifying the shuttle effect and realizing the high performance of flexible lithium-sulfur batteries(LSBs).Phase transformation of MoSe_(2) from the 2H phase ...Sophisticated efficient electrocatalysts are essential to rectifying the shuttle effect and realizing the high performance of flexible lithium-sulfur batteries(LSBs).Phase transformation of MoSe_(2) from the 2H phase to the 1T phase has been proven to be a significant method to improve the catalytic activity.However,precisely controllable phase engineering of MoSe_(2) has rarely been reported.Herein,by in situ Li ions intercalation in MoSe_(2),a precisely controllable phase evolution from 2H-MoSe_(2) to 1T-MoSe_(2) was realized.More importantly,the definite functional relationship between cut-off voltage and phase structure was first identified for phase engineering through in situ observation and modulation methods.The sulfur host(CNFs/1T-MoSe_(2))presents high charge density,strong polysulfides adsorption,and catalytic kinetics.Moreover,Li-S cells based on it display capacity retention of 875.3mAh g^(-1) after 500 cycles at 1 C and an areal capacity of 8.71mAh cm^(-2) even at a high sulfur loading of 8.47mg cm^(-2).Furthermore,the flexible pouch cell exhibiting decent performance will endow a promising potential in the wearable energy storage field.This study proposes an effective strategy to precisely control the phase structure of MoSe_(2),which may provide the reference to fabricate the highly efficient electrocatalysts for LSBs and other energy systems.展开更多
First-principles calculations have been performed to study the lithium intercalations in MoS2. The formation energies, changes of volumes, electronic structures and charge densities of the lithium intercalations in Mo...First-principles calculations have been performed to study the lithium intercalations in MoS2. The formation energies, changes of volumes, electronic structures and charge densities of the lithium intercalations in MoS2 are presented. Our calculations show that during lithium intercalations in MoS2, the lithium intercalation formation energies per lithium atom are between 2.5 eV to 3.0 eV. The volume expansions of MoS2 due to lithium intercalations are relatively small展开更多
Compared with conventional graphite anode,hard carbons have the potential to make reversible lithium storage below 0 V accessible due to the formation of dendrites is slow.However,under certain conditions of high curr...Compared with conventional graphite anode,hard carbons have the potential to make reversible lithium storage below 0 V accessible due to the formation of dendrites is slow.However,under certain conditions of high currents and lithiation depths,the irreversible plated lithium occurs and then results in the capacity losses.Herein,we systematically explore the true reversibility of hard carbon anodes below 0 V.We identify the lithiation boundary parameters that control the reversible capacity of hard carbon anodes.When the boundary capacity is controlled below 400 mAh g−1 with current density below 50 mA g−1,no lithium dendrites are observed during the lithiation process.Compared with the discharge cut-off voltage to 0 V,this boundary provides a nearly twice reversible capacity with the capacity retention of 80%after 172 cycles.The results of characterization and finite element model reveal that the large reversible capacity below 0 V of hard carbon anodes is mainly benefited from the dual effect of lithium intercalation and reversible lithium film.After the lithium intercalation,the over-lithiation induces the quick growth of lithium dendrites,worsening the electrochemical irreversibility.This work enables insights of the potentially low-voltage performance of hard carbons in lithium-ion batteries.展开更多
Lithium-ion batteries(LIBs)have been used to power various electric devices and store energy,but their toxic components by using inorganic materials generally cause serious environmental issues when disused.Recently,e...Lithium-ion batteries(LIBs)have been used to power various electric devices and store energy,but their toxic components by using inorganic materials generally cause serious environmental issues when disused.Recently,environmentally friendly and naturally abundant organic compounds have been adopted as promising electrode materials for next-generation LIBs.Herein,a new organic anode electrode based on sodium citrate is proposed,which shows gradually activated electrochemical behavior and delivers a high reversible capacity of 776.8 mAh·g^(-1)after 1770 cycles at a current density of 2 A·g^(-1).With the aid of the electrochemical characterization,Fourier-transform infrared(FTIR)and X-ray photoelectron spectroscopy(XPS)analysis,the lithium uptake mechanism of sodium citrate-based anodes is identified to be a combination of three-electron lithiation/delithiation and fast Li+intercalation/deintercalation processes,in which Faradaic reactions could offer a theoretical contribution of312 mAh·g^(-1)and intercalation pseudocapacitance would provide extra capacity.This work demonstrates the great potential for developing high-capacity organic electrodes for LIBs in future.展开更多
基金National Natural Science Foundation of China,Grant/Award Numbers:U2004172,51972287 and 51502269the Foundation for University Key Teachers of Henan Province,Grant/Award Number:2020GGJS009Natural Science Foundation of Henan Province,Grant/Award Number:202300410368。
文摘Sophisticated efficient electrocatalysts are essential to rectifying the shuttle effect and realizing the high performance of flexible lithium-sulfur batteries(LSBs).Phase transformation of MoSe_(2) from the 2H phase to the 1T phase has been proven to be a significant method to improve the catalytic activity.However,precisely controllable phase engineering of MoSe_(2) has rarely been reported.Herein,by in situ Li ions intercalation in MoSe_(2),a precisely controllable phase evolution from 2H-MoSe_(2) to 1T-MoSe_(2) was realized.More importantly,the definite functional relationship between cut-off voltage and phase structure was first identified for phase engineering through in situ observation and modulation methods.The sulfur host(CNFs/1T-MoSe_(2))presents high charge density,strong polysulfides adsorption,and catalytic kinetics.Moreover,Li-S cells based on it display capacity retention of 875.3mAh g^(-1) after 500 cycles at 1 C and an areal capacity of 8.71mAh cm^(-2) even at a high sulfur loading of 8.47mg cm^(-2).Furthermore,the flexible pouch cell exhibiting decent performance will endow a promising potential in the wearable energy storage field.This study proposes an effective strategy to precisely control the phase structure of MoSe_(2),which may provide the reference to fabricate the highly efficient electrocatalysts for LSBs and other energy systems.
基金This work was supported by the National Natural Science Foundation of China under Grant No.10374076by the Natural Science Foundation of Fujian Province under Grant Nos.E0410025 and E032001.
文摘First-principles calculations have been performed to study the lithium intercalations in MoS2. The formation energies, changes of volumes, electronic structures and charge densities of the lithium intercalations in MoS2 are presented. Our calculations show that during lithium intercalations in MoS2, the lithium intercalation formation energies per lithium atom are between 2.5 eV to 3.0 eV. The volume expansions of MoS2 due to lithium intercalations are relatively small
基金This work gratefully acknowledges the support of National Key Research and Development(R&D)Program of China(grant No.2020YFB1505800)National Science Foundation for Excellent Young Scholars of China(grant No.2192285)+2 种基金the Youth Innovation Promotion Association of CAS(grant No.2019178)Research and Development Project of Key Core and Common Technology of Shanxi Province(grant No.2020xxx014)Key Research and Development(R&D)Projects of Shanxi Province(grant No.202102040201003).
文摘Compared with conventional graphite anode,hard carbons have the potential to make reversible lithium storage below 0 V accessible due to the formation of dendrites is slow.However,under certain conditions of high currents and lithiation depths,the irreversible plated lithium occurs and then results in the capacity losses.Herein,we systematically explore the true reversibility of hard carbon anodes below 0 V.We identify the lithiation boundary parameters that control the reversible capacity of hard carbon anodes.When the boundary capacity is controlled below 400 mAh g−1 with current density below 50 mA g−1,no lithium dendrites are observed during the lithiation process.Compared with the discharge cut-off voltage to 0 V,this boundary provides a nearly twice reversible capacity with the capacity retention of 80%after 172 cycles.The results of characterization and finite element model reveal that the large reversible capacity below 0 V of hard carbon anodes is mainly benefited from the dual effect of lithium intercalation and reversible lithium film.After the lithium intercalation,the over-lithiation induces the quick growth of lithium dendrites,worsening the electrochemical irreversibility.This work enables insights of the potentially low-voltage performance of hard carbons in lithium-ion batteries.
基金financially supported by the National Natural Science Foundation of China(Nos.21875155,51675275 and 21473119)the Scientific and Technological Research Program of Chongqing Municipal Education Commission(No.KJQN201900527)the support from the Key Laboratory for Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province,Suzhou,China。
文摘Lithium-ion batteries(LIBs)have been used to power various electric devices and store energy,but their toxic components by using inorganic materials generally cause serious environmental issues when disused.Recently,environmentally friendly and naturally abundant organic compounds have been adopted as promising electrode materials for next-generation LIBs.Herein,a new organic anode electrode based on sodium citrate is proposed,which shows gradually activated electrochemical behavior and delivers a high reversible capacity of 776.8 mAh·g^(-1)after 1770 cycles at a current density of 2 A·g^(-1).With the aid of the electrochemical characterization,Fourier-transform infrared(FTIR)and X-ray photoelectron spectroscopy(XPS)analysis,the lithium uptake mechanism of sodium citrate-based anodes is identified to be a combination of three-electron lithiation/delithiation and fast Li+intercalation/deintercalation processes,in which Faradaic reactions could offer a theoretical contribution of312 mAh·g^(-1)and intercalation pseudocapacitance would provide extra capacity.This work demonstrates the great potential for developing high-capacity organic electrodes for LIBs in future.