Suppression of Co(Ⅱ)ion deposition and hazards:Regulation of SEI film composition and structure

Despite the presence of Li F components in the solid electrolyte interphase(SEI)formed on the graphite anode surface by conventional electrolyte,these Li F components primarily exist in an amorphous state,rendering them incapable of effectively inhibiting the exchange reaction between lithium ions and transition metal ions in the electrolyte.Consequently,nearly all lithium ions within the SEI film are replaced by transition metal ions,resulting in an increase in interphacial impedance and a decrease in stability.Herein,we demonstrate that the SEI film,constructed by fluoroethylene carbonate(FEC)additive rich in crystalline Li F,effectively inhibits the undesired Li^(+)/Co^(2+)ion exchange reaction,thereby suppressing the deposition of cobalt compounds and metallic cobalt.Furthermore,the deposited cobalt compounds exhibit enhanced structural stability and reduced catalytic activity with minimal impact on the interphacial stability of the graphite anode.Our findings reveal the crucial influence of SEI film composition and structure on the deposition and hazards associated with transition metal ions,providing valuable guidance for designing next-generation electrolytes.

宣肺败毒汤治疗新型冠状病毒感染肺炎的随机对照试验

[目的]评价宣肺败毒汤治疗普通型新型冠状病毒感染(COVID-19)的有效性和安全性。[方法]将符合条件的普通型COVID-19患者随机分为A组(宣肺败毒汤联合常规治疗)、B组(甘露消毒汤联合常规治疗)、C组(仅常规治疗)。疗程14天。主要结局指标为SARS-CoV-2核酸转阴时间和住院天数。次要结局指标是症状消失率。安全性指标为药物相关不良事件。[结果]共纳入103例普通型COVID-19患者,随机分为A组(34例)、B组(35例)和C组(34例)。SARS-CoV-2核酸转阴时间最短的是A组(9.88±3.62天),其次是C组(11.20±2.93天)和B组(12.69±4.11天)。三组间差异有统计学意义(P=0.010)。A组住院天数最短(14.00±6.55天),其次是B组(15.40±4.02天)和C组(16.38±5.73天)。组间差异有统计学意义(P=0.019)。各组症状消失率比较,差异无统计学意义(P>0.05)。三组均未发生药物相关不良事件。[结论]宣肺败毒汤治疗普通型COVID-19安全有效,可缩短SARS-CoV-2核酸转阴时间及住院时间。

Synergistic interphase modification with dual electrolyte additives to boost cycle stability of high nickel cathode for all-climate battery

B-containing electrolyte additives are widely used to enhance the cycle performance at low temperature and the rate capability of lithium-ion batteries by constructing an efficient cathode electrolyte interphase(CEI)to facilitate the rapid Li+migration.Nevertheless,its wide-temperature application has been limited by the instability of B-derived CEI layer at high temperature.Herein,dual electrolyte additives,consisting of lithium tetraborate(Li_(2)TB)and 2,4-difluorobiphenyl(FBP),are proposed to boost the widetemperature performances of LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM)cathode.Theoretical calculation and electrochemical performances analyses indicate that Li_(2)TB and FBP undergo successive decomposition to form a unique dual-layer CEI.FBP acts as a synergistic filming additive to Li_(2)TB,enhancing the hightemperature performance of NCM cathode while preserving the excellent low-temperature cycle stability and the superior rate capability conferred by Li_(2)TB additive.Therefore,the capacity retention of NCM‖Li cells using optimal FBP-Li_(2)TB dual electrolyte additives increases to 100%after 200 cycles at-10℃,99%after 200 cycles at 25℃,and 83%after 100 cycles at 55℃,respectively,much superior to that of base electrolyte(63%/69%/45%).More surprisingly,galvanostatic c ha rge/discharge experiments at different temperatures reveal that NCM‖Li cells using FBP-Li_(2)TB additives can operate at temperatures ranging from-40℃to 60℃.This synergistic interphase modification utilizing dual electrolyte additives to construct a unique dual-layer CEI adaptive to a wide temperature range,provides valuable insights to the practical applications of NCM cathodes for all-climate batteries.

Tackling application limitations of high-safetyγ-butyrolactone electrolytes:Exploring mechanisms and proposing solutions

Developing wide-temperature and high-safety lithium-ion batteries(LIBs)presents significant challenges attributed to the absence of suitable solvents possessing broad liquid range and non-flammability properties.γ-Butyrolactone(GBL)has emerged as a promising solvent;however,its incompatibility with graphite anode has hindered its application.This limitation necessitates a comprehensive investigation into the underlying mechanisms and potential solutions.In this study,we achieve a molecular-level understanding of the perplexing interphase formation process by employing in-situ spectroelectrochemical techniques and density function calculations.Our findings reveal that,even at high salt concentrations,GBL consistently occupies the primary Li^(+)solvation sheath,leading to extensive GBL decomposition and the formation of a high-impedance and inorganic-poor solid-electrolyte interphase(SEI)layer.Contrary to manipulating solvation structures,our research demonstrates that the utilization of filmforming additives with higher reduction potential facilitates the pre-establishment of a robust SEI film on the graphite anode.This approach effectively inhibits GBL decomposition and significantly enhances the battery's lifespan.This study provides the first reported intrinsic understanding of the unique GBLgraphite incompatibility and offers valuable insights for the development of wide-temperature and high-safety LIBs.

Carboxymethyl chitosan/poly(ethylene oxide)water soluble binder:Challenging application for 5V LiNi0.5Mn1.5O4 cathode

Carboxymethyl chitosan/poly(ethylene oxide)(CCTS/PEO) composite is firstly reported as a water soluble binder for the application of 5V LiNi_(0.5)Mn_(1.5)O_4 cathode in Li-ion batteries. Both CCTS and PEO show a high electrochemical oxidation potential of above 5.0 V(vs. Li/Li+). The electrochemical performances of LiNi_(0.5)Mn_(1.5)O_4(LNMO) cathodes with CCTS/PEO composite binders of different mass rates are investigated, it is found that LiNi_(0.5)Mn_(1.5)O_4 cathode with an optimized CCTS/PEO(85/15, w/w) composite exhibits a slightly better cycling performance than that of polyvinylidene fluoride(PVDF), retaining 81.4% capacity as compared with 79.8% for PVDF at 0.5C rate after 200 cycles. LNMO with PEO/CCTS(85/15,w/w) exhibited the better rate capability than that of PVDF. These results demonstrate that CCTS/PEO composite can be potentially used as a water-soluble binder for 5 V LNMO cathode.