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A water-soluble conductive composite binder consisting of carboxymethyl chitosan (CCTS) as a binder and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as a conduction-promoting agent is reported for the LiFePO 4 (LFP) cathode in Li-ion batteries. The introduction of conductive PEDOT:PSS as a conductive composite binder facilitates the formation of homogeneous and continuous conducting bridges throughout the electrode and raises the compaction density of the electrode sheet by decreasing the amounts of the commonly used conducting agent of acetylene black. The optimized replacement ratios of acetylene black with PEDOT:PSS (acetylene black/PEDOT:PSS = 1:1, by weight) are obtained by measuring electrical conductivity, peel strength and compaction density of the electrode sheets. The LFP half-cell with the optimized conductive binder exhibits better cycling and rate performance and more favorable electrochemical kinetics than that using only acetylene black conducting agent. The pilot application of PEDOT:PSS/CCTS binder in 10 Ah CCTS-LFP prismatic cell exhibits a comparable cycling performance, retaining 89.7% of capacity at 1 C/2 C (charge/discharge) rate as compared with 90% for commercial PVDF-LFP over 1000 cycles, and better rate capability than that of commercial PVDF-LFP, retaining 98% capacity of 1 C at 7 C rate as compared with 95.4% for PVDF-LFP.

Two fluorosilanes with oligo(ethylene oxide) unites were synthesized through hydrosilylation of chlorosilane with allyl substituted oligo(ethylene oxide) ether followed by fluorination with potassium fluoride. The synthesized fluorosilane compounds exhibited lower viscosity, higher dielectric constant and higher oxidation potential, compared with their non-fluorination counterparts. Difluoro(3-(2-(2-methoxyethoxy)ethoxy)propyl)methylsilane (DFSM 2 ), one of the two compounds, was evaluated as high-voltage and thermal stable electrolyte co-solvent with the conventional carbonate-based electrolytes. Using an optimized electrolyte of 1M LiPF 6 in EC/DFSM 2 /EMC (2/3/5 in vol .) with addition of 5 wt % fluoroethylene carbonate (FEC), high-voltage LiCoO 2 (LCO)/graphite full cell displayed outstanding cycling stability of 92.5% capacity retention after 135 cycles at 4.4 V upper cutoff voltage. Characterized by differential scanning calorimetry (DSC) analysis, the DFSM 2 -based electrolyte demonstrated higher thermal stability with lithiated graphite anode and delithiated LCO cathode, thus better safety feature compared with the conventional electrolyte.

Three choline-based ionic liquids functionalized with trimethylsilyl, allyl, and cynoethyl groups are synthesized in an inexpensive route as safe electrolytes for high-voltage lithium-ion batteries. The thermal stabilities, viscosities, conductivities, and electrochemical windows of these ILs are reported. Hybrid electrolytes were formulated by doping with 0.6 M LiPF6/0.4 M lithium oxalydifluoroborate (LiODFB) as salts and dimethyl carbonate (DMC) as co-solvent. By using 0.6 M LiPF6/0.4 M LiODFB trimethylsilylated choline-based IL (SN1IL-TFSI)/DMC as electrolyte, LiCoO2/graphite full cell showed excellent cycling performance with a capacity of 152 mAh g-1 and 99% capacity retention over 90 cycles at a cut-off voltage of 4.4 V. The propagation rate of SN1IL-TFSI)/DMC electrolyte is only one quarter of the commercial electrolyte (1 M LiPF6 EC/DEC/DMC, v/v/v = 1/1/1), suggesting a better safety feature.

Al-substituted Ni(OH) 2 samples with Al 3+ /Ni 2+ mole ratio of 0%, 10% and 20% have been prepared by a very facile chemical co-precipitation method. The microstructure of the prepared samples are analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TGA), and Field emission scanning electron microscopy (FESEM). The results reveal that the pure Ni(OH) 2 sample is β -Ni(OH) 2 with nanosheets hierarchical structure; the sample with 10% Al is mixed phase α / β- Ni(OH) 2 with hybrid nanosheets/nanoparticles hierarchical structure; the sample with 20% Al is α- Ni(OH) 2 with irregular nanoparticles hierarchical structure. The lithium storage performances of the prepared samples are characterized by cyclic voltammograms (CV), electrochemical impedance spectroscopy (EIS), and charge–discharge tests. The results demonstrate that Al substitution could improve the lithium storage performances of nickel hydroxide. In particular, the mixed phase α / β- Ni(OH) 2 with 10% Al exhibited the highest electrochemical activity, the best rate performance, and superior cycling stability. For example, after 30 charge/discharge cycles under a current density of 200 mA g −1 , the mixed phase α / β- Ni(OH) 2 with 10% Al can still deliver a specific discharge capacity of 964 mAh g −1 , much higher than of for the α- Ni(OH) 2 with 20% Al (681 mAh g −1 ) and the pure Ni(OH) 2 (419 mAh g −1 ).

A novel aminoakyldisiloxane compound, (3-(N,N-dimethylamino)diethoxypropyl) pentamethyldisiloxane (DSON), is reported as an effective electrolyte additive for improving the electrochemical performances of high energy density power batteries of nickel-rich LiNi0.6Co0.2Mn0.2O2 (NCM622)/graphite. The NCM622/graphite cells using DSON addition in the carbonate-based reference electrolyte exhibit enhanced electrochemical performances, especially high temperature performances including long cycle life and high temperature storage. The pouch cell (1 Ah) with 0.2 wt% DSON retained a capacity of 88% as compared with 84% for that without DSON in electrolyte after 200 cycles at 45 °C. The mechanism investigation reveals that DSON acts as a film-forming additive for constructing uniform conductive cathode electrolyte interphase (CEI) layer upon NCM622 particles, which suppresses the internal cracks and prohibits the irreversible phase transformation of NCM622. DSON also serves as an effective water/acid scavenger and inhibits the hydrolysis of LiPF6, thus effectively blocking the occurrence of side reactions and the dissolution of transition metal ions from cathode. Therefore, NCM622 cathode sheet maintains a better integrity surface morphology after 100 cycles. This work demonstrates that aminoakyldisiloxane is promising for practical use as effective electrolyte additive for high energy density power batteries of nickel-rich NCM/graphite.

Selenium-sulfur solid solutions (SexSy) attracts soaring attention owing to its improved electrical conductivity over sulfur and higher theoretical specific capacity than selenium. Herein, high-performance lithium-selenium/sulfur batteries with a dual-confined cathode configuration by encapsulating SeS2 in double-layered hollow micro/mesoporous carbon spheres (DSMCs) with a conductive polyaniline (PANI) protection sheath are proposed. Polysulfides/polyselenides are efficiently restricted in the cathode via physical and chemical entrapment from DSMCs and PANI as well as chemical binding between selenium and sulfur. Benefiting from the distinct advantages of SeS2 and the well-constructed host framework, the cathode achieves high capacity utilization of 1018 mAh g−1 at 0.2 A g−1, together with outstanding rate capability of 619 mAh g−1 at 2 A g−1 and excellent cycle life over 500 cycles with almost 100% Coulombic efficiency. The novel SexSy-based cathode demonstrates a promising route to surmount some bottlenecks of current lithium-sulfur systems for high-performance rechargeable batteries.

Novel nanostructured silicon composites, Si/Poly(3,4-ethylenedioxythiophene) nanowire network (Si/PNW) and Si/(S-doped-carbon nanowire network) (Si/S-CNW), are prepared by a soft-template polymerization of 3,4-ethylenedioxythiophene (EDOT) using sodium dodecyl sulfate (SDS) as surfactant with the presence of Si nanoparticles and a subsequent carbonization of Si/PNW, respectively. The presence of Si nanoparticles in the soft-template polymerization of EDOT plays a critical role in the formation of PEDOT nanowire network instead of 1D nanowire. After the carbonization of PEDOT, the S-doped-carbon nanowire network matrix shows higher electrical conductivity than PNW counterpart, which facilitates to construct robust conductive bridges between Si nanoparticles and provide large electrode/electrolyte interfaces for rapid charge transfer reactions. Thus, Si/S-CNW composite exhibits excellent cycling stability and rate capability as anode material, retaining a specific capacity of 820 mAh g−1 after 400 cycles with a very small capacity fade of 0.09% per cycle.

Organosilicon compounds containing nitrile and oligo(ethylene oxide) substituents are synthesized as safe electrolytes for high-voltage lithium-ion batteries. We firstly report that these organosilicon electrolytes could be stably cycled at an upper cutoff voltage of 4.4 V in LiCoO2/graphite full cells.

Carboxymethyl chitosan (C-chitosan) is investigated as a new water soluble binder for Si anode of Li-ion batteries. The Fourier transformation infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements reveal that the strong hydrogen bonding is formed between the hydroxylated Si surface and the polar groups (–OH, –COOH and –NH 2 ) of C-chitosan. The Si/C-chitosan anode (Si:carbon black:C-chitosan = 62:30:8 in weight ratio) exhibits a high first discharge capacity (4270 mAh g −1 ) with a first coulombic efficiency of 89%, and maintains a capacity of 950 mAh g −1 at the current density of 500 mA g −1 over 50 cycles.