High voltage is necessary for high energy lithium-ion batteries but difficult to achieve because of the highly deteriorated cyclability of the batteries.A novel strategy is developed to extend cyclability of a high vo...High voltage is necessary for high energy lithium-ion batteries but difficult to achieve because of the highly deteriorated cyclability of the batteries.A novel strategy is developed to extend cyclability of a high voltage lithium-ion battery,LiNi_(0.5)Mn_(1.5)O_(4)/Graphite(LNMO/Graphite)cell,which emphasizes a rational design of an electrolyte additive that can effectively construct protective interphases on anode and cathode and highly eliminate the effect of hydrogen fluoride(HF).5-Trifluoromethylpyridine-trime thyl lithium borate(LTFMP-TMB),is synthesized,featuring with multi-functionalities.Its anion TFMPTMB-tends to be enriched on cathode and can be preferentially oxidized yielding TMB and radical TFMP-.Both TMB and radical TFMP can combine HF and thus eliminate the detrimental effect of HF on cathode,while the TMB dragged on cathode thus takes a preferential oxidation and constructs a protective cathode interphase.On the other hand,LTFMP-TMB is preferentially reduced on anode and constructs a protective anode interphase.Consequently,a small amount of LTFMP-TMB(0.2%)in 1.0 M LiPF6in EC/DEC/EMC(3/2/5,wt%)results in a highly improved cyclability of LNMO/Graphite cell,with the capacity retention enhanced from 52%to 80%after 150 cycles at 0.5 C between 3.5 and 4.8 V.The as-developed strategy provides a model of designing electrolyte additives for improving cyclability of high voltage batteries.展开更多
Although the operating mechanism of sodium-ion battery(SIB)resembles that of lithium-ion battery,common film-forming additive for lithium-ion battery does not play its role in SIB.Therefore,it is essential to tailor n...Although the operating mechanism of sodium-ion battery(SIB)resembles that of lithium-ion battery,common film-forming additive for lithium-ion battery does not play its role in SIB.Therefore,it is essential to tailor new additives for SIB.Hard carbon(HC),as the most used anode material of SIB,has the disadvantage of interphasial instability,especially under the condition of long-term cycling.The incessant accumulation of electrolyte decomposition products leads to a significant increase in interphasial impedance and a sharp decline in discharge capacity.In this work,N-phenyl-bis(trifluoromethanesulfonimide)(PTFSI)was proposed as a novel film-forming electrolyte additive,which effectively enhances the long-term cycling performance for HC anode in SIB.The passivation film generated from the preferential reduction of PTFSI improves the capacity retention of HC/Na half-cell from 0%to 68%after 500 cycles.Profoundly,the enhanced interphasial stability of HC anode results in a 52%increase in capacity retention of HC/Na_(3)V_(2)(PO_(4))_(3)full-cells after 100 cycles.展开更多
基金supported by the National Natural Science Foundation of China(22179041)。
文摘High voltage is necessary for high energy lithium-ion batteries but difficult to achieve because of the highly deteriorated cyclability of the batteries.A novel strategy is developed to extend cyclability of a high voltage lithium-ion battery,LiNi_(0.5)Mn_(1.5)O_(4)/Graphite(LNMO/Graphite)cell,which emphasizes a rational design of an electrolyte additive that can effectively construct protective interphases on anode and cathode and highly eliminate the effect of hydrogen fluoride(HF).5-Trifluoromethylpyridine-trime thyl lithium borate(LTFMP-TMB),is synthesized,featuring with multi-functionalities.Its anion TFMPTMB-tends to be enriched on cathode and can be preferentially oxidized yielding TMB and radical TFMP-.Both TMB and radical TFMP can combine HF and thus eliminate the detrimental effect of HF on cathode,while the TMB dragged on cathode thus takes a preferential oxidation and constructs a protective cathode interphase.On the other hand,LTFMP-TMB is preferentially reduced on anode and constructs a protective anode interphase.Consequently,a small amount of LTFMP-TMB(0.2%)in 1.0 M LiPF6in EC/DEC/EMC(3/2/5,wt%)results in a highly improved cyclability of LNMO/Graphite cell,with the capacity retention enhanced from 52%to 80%after 150 cycles at 0.5 C between 3.5 and 4.8 V.The as-developed strategy provides a model of designing electrolyte additives for improving cyclability of high voltage batteries.
基金supported by the National Natural Science Foundation of China(No.21972049)the Guangdong Program for Distinguished Young Scholar(No.2017B030306013).
文摘Although the operating mechanism of sodium-ion battery(SIB)resembles that of lithium-ion battery,common film-forming additive for lithium-ion battery does not play its role in SIB.Therefore,it is essential to tailor new additives for SIB.Hard carbon(HC),as the most used anode material of SIB,has the disadvantage of interphasial instability,especially under the condition of long-term cycling.The incessant accumulation of electrolyte decomposition products leads to a significant increase in interphasial impedance and a sharp decline in discharge capacity.In this work,N-phenyl-bis(trifluoromethanesulfonimide)(PTFSI)was proposed as a novel film-forming electrolyte additive,which effectively enhances the long-term cycling performance for HC anode in SIB.The passivation film generated from the preferential reduction of PTFSI improves the capacity retention of HC/Na half-cell from 0%to 68%after 500 cycles.Profoundly,the enhanced interphasial stability of HC anode results in a 52%increase in capacity retention of HC/Na_(3)V_(2)(PO_(4))_(3)full-cells after 100 cycles.
