1,3,5-Trifluorobenzene endorsed EC-free electrolyte for high-voltage and wide-temperature lithium-ion batteries

Ethylene carbonate(EC)is susceptible to the aggressive chemistry of nickel-rich cathodes,making it undesirable for high-voltage lithium-ion batteries(LIBs).The arbitrary elimination of EC leads to better oxidative tolerance but always incurs interfacial degradation and electrolyte decomposition.Herein,an EC-free electrolyte is deliberately developed based on gradient solvation by pairing solvation-protection agent(1,3,5-trifluorobenzene,F_(3)B)with propylene carbonate(PC)/methyl ethyl carbonate(EMC)formulation.F_(3)B keeps out of inner coordination shell but decomposes preferentially to construct robust interphase,inhibiting solvent decomposition and electrode corrosion.Thereby,the optimized electrolyte(1.1 M)with wide liquid range(-70–77℃)conveys decent interfacial compatibility and high-voltage stability(4.6 V for LiNi_(0.6)Mn_(0.2)Co_(0.2)O_(2),NCM622),qualifying reliable operation of practical NCM/graphite pouch cell(81.1%capacity retention over 600 cycles at 0.5 C).The solvation preservation and interface protection from F_(3)B blaze a new avenue for developing high-voltage electrolytes in next-generation LIBs.

Wide-temperature range and high safety electrolytes for highvoltage Li-metal batteries

Along with the keeping growing demand for high-energy-density energy storage system,high-voltage Li-metal batteries(LMBs)have attracted many attentions.In view of many defects of the commercial electrolytes,such as flammability,limited operation temperature range,and severe Li dendrite growth,non-flammable phosphate-based localized highly concentrated electrolytes(LHCE)have been explored as one of the safe electrolytes for LMBs.But until now there is rare report on wide-temperature range LMBs using phosphate-based electrolytes.Here,we prepare a wide-temperature LHCE,which is composed of lithium difluoro(oxalato)borate(LiDFOB),triethyl phosphate(TEP),and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether(HFE),and explore the applicability in wide-temperature LMBs from−40 to 70℃.In the LHCE,both TEP and HFE are non-flammable,and Li^(+) is highly coordinated with TEP and DFOB^(−),which can effectively inhibit the TEP decomposition on anode,and facilitate the preferential reduction of DFOB^(−),thus obtain a robust solid electrolyte interphase(SEI)to suppress Li dendrite growth and side reactions.Therefore,this LHCE can not only endow Li/Cu and Li/Li cells with high Coulombic efficiency(CE)and long cycling lifespan,but also be applied to LiFePO_(4)(LFP)/Li and LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)(NCM523)/Li LMBs.Most importantly,the NCM523/Li LMBs with LHCE can deliver stable cycling performance at 4.5 V high-voltage and high-temperature(70℃),as well as excellent low-temperature capacity retention even though both charging and discharging process were carried out at−40℃.

Superior wide-temperature lithium storage in a porous cobalt vanadate

Lithium ion batteries(LIBs)that can be operated under extended temperature range hold significant application potentials.Here in this work,we successfully synthesized Co2V2O7 electrode with rich porosity from a facile hydrothermal and combustion process.When applied as anode for LIBs,the electrode displayed excellent stability and rate performance in a wide range of temperatures.Remarkably,a stable capacity of 206 mAhg 1 was retained after cycling at a high current density of 10 A·g-1 for 6,000 cycles at room temperature(25℃).And even when tested under extreme conditions,i.e.,-20 and 60℃,the battery still maintained its remarkable stability and rate capability.For example,at-20℃,a capacity of 633 mAh·g 1 was retained after 50 cycles at 0.1 A·g 1;and even after cycling at 60℃ at 10 A·g-1 for 1,000 cycles,a reversible capacity of 885 mAh·g-1 can be achieved.We believe the development of such electrode material will fciliate progress of the next-generation LIBs with wide operating windows.

High-power and low-cost sodium-ion batteries with a wide operation temperature from -70℃ to 130℃

Low-cost sodium-ion batteries(SIBs)are promising candidates for grid-scale energy-storage systems,and the wide-temperature operations of SIBs are highly demanded to accommodate extreme weather.Herein,a low-cost SIB is fabricated with a Na_(4)Fe_(3)(PO_(4))_(2)P_(2)O_(7)(NFPP)cathode,a natural graphite(NG)anode,and an ether-based electrolyte.The prepared NG/NFPP batteries deliver a long lifespan of 1000 cycles,high-power density of 5938 W/kg,and remarkable rate performance of 10 A/g with a high capacity retention of 60%.Benefiting from the solvent co-intercalation process of the NG anode and the high Na^(+) diffusion rate of the NFPP cathode,the NG//NFPP battery displays outstanding performance at-40℃ and even can work at an ultralow temperature of-70℃.Furthermore,the high boiling point of the electrolytes and high thermal stability of the electrode materials also enable the high-temperature operation of the full battery up to 130℃.This work will guide the design of the wide-temperature SIBs.