Lithium(Li) metal is widely considered as a promising anode for next-generation lithium metal batteries(LMBs) due to its high theoretical capacity and lowest electrochemical potential. However, the uncontrollable form...Lithium(Li) metal is widely considered as a promising anode for next-generation lithium metal batteries(LMBs) due to its high theoretical capacity and lowest electrochemical potential. However, the uncontrollable formation of Li dendrites has prevented its practical application. Herein, we propose a kind of multifunctional electrolyte additives(potassium perfluorinated sulfonates) from the multi-factor principle for electrolyte additive molecular design(EDMD) view to suppress the Li dendrite growth. The effects of these additives are revealed through experimental results, molecular dynamics simulations and firstprinciples calculations. Firstly, K^(+)can form an electrostatic shield on the surface of Li anode to prevent the growth of Li dendrites. Secondly, potassium perfluorinated sulfonates can improve the activity of electrolytes as co-conductive salts, and lower the electro-potential of Li nucleation. Thirdly, perfluorinated sulfonate anions not only can change the Li^(+)solvation sheath structure to decrease the desolvation energy barrier and increase the ion migration rate, but also can be partly decomposed to form the superior solid electrolyte interphase(SEI). Benefited from the synergistic effects, an outstanding cycle life over250 h at 1 m A cm^(-2) is achieved in symmetric Li||Li cells. In particular, potassium perfluorinated sulfonate additives(e.g., potassium perfluorohexyl sulfonate, denoted as K+PFHS) can also contribute to the formation of high-quality cathode electrolyte interphase(CEI). As a result, Li||LiNi_(0.6)Mn_(0.2)Co_(0.2)O_(2) full cells exhibit significantly enhanced cycling stability. This multi-factor principle for EDMD offers a unique insight on understanding the electrochemical behavior of ion-type electrolyte additives on both the Li metal anode and high-voltage cathode.展开更多
The application of rechargeable lithium metal batteries(LMBs)has been hindered by the fast growth of lithium dendrites during charge and the limited cycling life because of the decomposition of the electrolyte at the ...The application of rechargeable lithium metal batteries(LMBs)has been hindered by the fast growth of lithium dendrites during charge and the limited cycling life because of the decomposition of the electrolyte at the interface.Here,we have developed a non-flammable triethyl phosphate(TEP)-based electrolyte with tris(hexafluoroisopropyl)phosphate(THFP)as an additive.The polar nature of the C–F bonding and the rich CF3 groups in THFP lowers its LUMO energy and HOMO energy to help form a stable,Li F-rich solid electrolyte interphase(SEI)layer through the reduction of THFP and increases the binding ability of the PF6-anions,which significantly suppresses lithium dendrite growth and reduces the electrolyte decomposition.Moreover,THFP participates in the formation of a thin,C–F rich electrolyte interphase(CEI)layer to provide the stable cycling of the cathode at a high voltage.The symmetric Li||Li and full Li/NCM622 cells with THFP additive have small polarization and long cycling life,which demonstrates the importance of the additive to the application of the LMBs.展开更多
Solid electrolyte interphase(SEI)is derived from electrolyte decomposition,and considered as extremely crucial interface,which has a huge influence on the reversible operation of lithium-ion batteries(LIBs)and lithium...Solid electrolyte interphase(SEI)is derived from electrolyte decomposition,and considered as extremely crucial interface,which has a huge influence on the reversible operation of lithium-ion batteries(LIBs)and lithium metal batteries(LMBs)[1-3],e.g.,the irreversible capacity,internal resistance,Coulombic efficiency,and cycling life of batteries[4-10].However,our knowledge on SEI components and structures is still limited although SEI has been studied for several decades.展开更多
基金supported by the National Natural Science Foundation of China (11675051)the China Postdoctoral Science Foundation (2020M672477)the Key Research and Development Program of Hunan Province,China (2018GK2031)。
文摘Lithium(Li) metal is widely considered as a promising anode for next-generation lithium metal batteries(LMBs) due to its high theoretical capacity and lowest electrochemical potential. However, the uncontrollable formation of Li dendrites has prevented its practical application. Herein, we propose a kind of multifunctional electrolyte additives(potassium perfluorinated sulfonates) from the multi-factor principle for electrolyte additive molecular design(EDMD) view to suppress the Li dendrite growth. The effects of these additives are revealed through experimental results, molecular dynamics simulations and firstprinciples calculations. Firstly, K^(+)can form an electrostatic shield on the surface of Li anode to prevent the growth of Li dendrites. Secondly, potassium perfluorinated sulfonates can improve the activity of electrolytes as co-conductive salts, and lower the electro-potential of Li nucleation. Thirdly, perfluorinated sulfonate anions not only can change the Li^(+)solvation sheath structure to decrease the desolvation energy barrier and increase the ion migration rate, but also can be partly decomposed to form the superior solid electrolyte interphase(SEI). Benefited from the synergistic effects, an outstanding cycle life over250 h at 1 m A cm^(-2) is achieved in symmetric Li||Li cells. In particular, potassium perfluorinated sulfonate additives(e.g., potassium perfluorohexyl sulfonate, denoted as K+PFHS) can also contribute to the formation of high-quality cathode electrolyte interphase(CEI). As a result, Li||LiNi_(0.6)Mn_(0.2)Co_(0.2)O_(2) full cells exhibit significantly enhanced cycling stability. This multi-factor principle for EDMD offers a unique insight on understanding the electrochemical behavior of ion-type electrolyte additives on both the Li metal anode and high-voltage cathode.
基金the National Natural Science Foundation of China(51971090 and U21A20311)。
文摘The application of rechargeable lithium metal batteries(LMBs)has been hindered by the fast growth of lithium dendrites during charge and the limited cycling life because of the decomposition of the electrolyte at the interface.Here,we have developed a non-flammable triethyl phosphate(TEP)-based electrolyte with tris(hexafluoroisopropyl)phosphate(THFP)as an additive.The polar nature of the C–F bonding and the rich CF3 groups in THFP lowers its LUMO energy and HOMO energy to help form a stable,Li F-rich solid electrolyte interphase(SEI)layer through the reduction of THFP and increases the binding ability of the PF6-anions,which significantly suppresses lithium dendrite growth and reduces the electrolyte decomposition.Moreover,THFP participates in the formation of a thin,C–F rich electrolyte interphase(CEI)layer to provide the stable cycling of the cathode at a high voltage.The symmetric Li||Li and full Li/NCM622 cells with THFP additive have small polarization and long cycling life,which demonstrates the importance of the additive to the application of the LMBs.
基金supported by the National Natural Science Foundation of China(51971090 and U21A20311)。
文摘Solid electrolyte interphase(SEI)is derived from electrolyte decomposition,and considered as extremely crucial interface,which has a huge influence on the reversible operation of lithium-ion batteries(LIBs)and lithium metal batteries(LMBs)[1-3],e.g.,the irreversible capacity,internal resistance,Coulombic efficiency,and cycling life of batteries[4-10].However,our knowledge on SEI components and structures is still limited although SEI has been studied for several decades.
