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A novel electrolyte additive, 3, 3, 3‐trifluoropropylmethyldimethoxysilane (TFPMDS), is first proposed to modify both the cathode and the anode of lithium‐ion batteries at the same time. Charging/discharging tests demonstrate that the electrolyte with 1 wt% TFPMDS not only greatly improves the capacity retention of LiNi0.5Mn1.5O4 (LNMO)//Li cell (29.6%→90.8%) and graphite//Li cell (68.1%→98.3%), but also successfully ensures the long‐term cycle stability of LNMO//graphite pouch cell at 4.9 V. Further electrochemical measurements combining with spectroscopic characterization and theoretical calculations indicate that TFPMDS additive displays three principal functions: 1) Be preferentially oxidized to build a robust cathode electrolyte interphase (CEI) enriched in F/Si species with F‐rich nature of strong oxidation‐resistance. 2) Be able to scavenge the hazardous HF, F−, and H+ through its strong binding with these species and thus to protect LNMO at high‐voltage. 3) Be preferentially adsorbed on the graphite surface to form a "framework", and to co‐construct an elastic solid electrolyte interphase (SEI) after the reduction of ethylene carbonate. Importantly, the Si─O group within TFPMDS is especially important for constructing a "molecular bridge" at the CEI/SEI interphase coupling the inorganic and organic species to improve its compatibility, stability, and elasticity. [ABSTRACT FROM AUTHOR]

LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811)/graphite battery is extensively concerned due to its high specific energy and low-cost. However, the unstable cathode/solid electrolyte interface (CEI/SEI) in carbonate-based electrolyte limits its development, especially under high voltage and high temperature. Herein, a novel electrolyte with 3-cyano-2,5,6-trifluoronicotinonitrile (CTFP) as an additive is proposed to construct a highly stable interface film on both cathode and anode to improve the electrochemical performance of NCM811/graphite battery. The experimental characterizations and theoretical calculations demonstrate that CTFP can preferentially catch PF 6 − on the NCM811 surface and then be oxidized to generate a N-containing polymer which can strongly absorb PF 5 and inhibit the formation of HF and the dissolution of transition metal (TM) ions on the cathode, and meanwhile, it is reduced to form a LiF-rich SEI on the anode. As a result, by adding 0.5 wt% CTFP into the basic electrolyte, the capacity retention of commercial NCM811/graphite pouch cell with 1800 mAh can be enhanced from 48 % to 75 % at 1 C after 200 cycles between 3.0 V and 4.35 V at 25 °C and the capacity retention of NCM811/graphite pouch cell with 16 mAh is improved from 46 % to 69 % at 1 C after 300 cycles between 3.0 V and 4.25 V at 55 °C. This new additive provides a universal strategy to establish a highly stable interface film on both NCM811 and graphite for high performance lithium-ion batteries. [Display omitted] • CTFP as a novel electrolyte additive can construct a highly stable interface film on both cathode and anode, and increase cycling performance of NCM811/graphite pouch cell with 1.8 Ah conspicuously. • CTFP preferentially catches PF 6 − on the NCM811 surface and then is oxidized to generate a N-containing polymer to inhibit the formation of HF and the dissolution of transition metal ions on the cathode. • CTFP is preferentially reduced to form a LiF-rich SEI on the anode. [ABSTRACT FROM AUTHOR]

Two novel donor-acceptor (D-A)-conjugated polymers, poly[(thiophene-2,5-yl)-((benzo[1,2-b:6,5-b′]dithiophene-4,5-dione)-2,7-yl)] (PTDT) and poly[((2,3-dihydrothieno[3,4-b] [1-2]dioxine)-5,7-diyl)-((benzo[1,2-b:6,5-b′]dithiophene-4,5-dione)-2,7-diyl)] (PTDO), have been synthesized with the same acceptor unit of benzo[1,2-b:6,5-b′]dithiophene-4,5-dione and different donor units of thiophene (Th) and 3,4-ethylenedioxothiphene (EDOT), respectively. And then, two composites (PTDT@C and PTDO@C) are made by coating the polymers on the surface of active carbon with an in situ method, which are used as the electrode materials of lithium-ion battery. The reversible capacities of PTDT@C and PTDO@C are 246.9 and 322.3 mAh g−1 at 0.1 A g−1 after 300 cycles running, respectively. By deducing the capability contribution of pure carbon, the theoretical capacities of the pure polymers are calculated to be 596 and 991 mAh g−1, respectively, for PTDT and PTDO, which correspond to the lithium storage number of 6.7 and 13.3, respectively, for the least repeating unit of the polymers. With the help of theoretical calculations, the underlying mechanisms for the different electrochemical performances of the polymers are discussed and revealed. The structure-activity relationship discussed in this work may provide the design principle for the construction of the D-A-type polymers used as high-capacity electrode materials for organic rechargeable batteries. [ABSTRACT FROM AUTHOR]

As a new type of electrode material, transition metal silicates anode has drawn increasing attention owing to high theoretical capacity, sufficient reserves and nontoxicity. Herein, a unique flower-shaped cobalt silicate was fabricated via an alkali-assisted hydrothermal synthesis method, which feathered large specific surface area and abundant meso-pores. Serving as an anode material for lithium ion batteries, the hierarchical CoSiO 2 material exhibited excellent cycling stability (1111 mAh g−1 at 0.1 A g−1 after 200 cycles) and superior rate capability (411 mAh g−1 at 10 A g−1). The novel structure of F–CoSiO 2 anode not only provided abundant active sites for electrochemical reactions and effectively facilitated the migration of Li ions during charge-discharge process, but also contributed to the primary pseudocapacitive charge storage behaviors. This work may open up opportunities in structure design and represent the enormous potential of hierarchical transition metal silicate as practical advanced electrode for lithium storage. [Display omitted] • A novel flower-shaped CoSiO 2 anode material for lithium ion batteries was designed and fabricated firstly. • The 3D architecture assembled by 2D nanosheets generated large surface area and abundant mesopores. • The hierarchical structure greatly shortened mass diffusion and fascinated the transport of Li ions. • The CoSiO 2 material exhibited remarkable cycling and rate performance. [ABSTRACT FROM AUTHOR]