A Li/CO 2 -O 2 (2 : 1, volume ratio) battery and a Li/CO 2 battery with discharging specific capacities of 1808 mA h g À1 and 1032 mA h g À1 , respectively, are reported. Li 2 CO 3 is the main discharge product in the Li/CO 2 -O 2 (2 : 1) battery and can be decomposed during charging. In the Li/CO 2 battery, the main discharge products could be Li 2 CO 3 and carbon. Both batteries can be cycled reversibly at room temperature. Experimental sectionHigh pure anhydrous LiCF 3 SO 3 ($99.995%, Sigma Aldrich Co.) was used as received. TEGDME ($99%, Sigma Aldrich Co.) was purchased and dehydrated with 0.3 nm molecular sieves (Metrohm Ltd., Switzerland). Then, LiCF 3 SO 3 was dissolved in TEGDME in a molar ratio of 1 : 4 to form the electrolyte. The cathode composition was Ketjen Black (KB) and PTFE

The microstructure and mechanical properties of the solid electrolyte interphase (SEI) in non-aqueous lithium ion batteries are key issues for understanding and optimizing the electrochemical performance of lithium batteries. In this report, the three-dimensional (3D) multi-layered structures and the mechanical properties of the SEI formed on a silicon anode material for next generation lithium ion batteries have been visualized directly for the first time, through a scanning force spectroscopy method. The coverage of the SEI on silicon anodes is also obtained through 2D projection plots. The effects of temperature and the function of additives in the electrolyte on the SEI can be understood accordingly. A modified model about dynamic evolution of the SEI on the silicon anode material is also proposed, which aims to explain why the SEI is very thick and how the multi-layered structure is formed and decomposed dynamically.

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High-Ni layered oxide cathode is considered as one of the most promising cathodes for high-energydensity lithium-ion batteries due to its high capacity and low cost. However, surficial residues, such as NiO-type rock-salt phase and Li 2 CO 3 , are often formed at the particle surface due to the high reactivity of Ni 3+ , and inevitably result in an inferior electrochemical performance, hindering the practical application. Herein, unprecedentedly clean surfaces without any surficial residues are obtained in a representative LiNi 0.8 Co 0.2 O 2 cathode by Ti gradient doping. High-resolution TEM reveals that the particle surface is composed of disordered layered phase (~ 6 nm in thickness) with the same rhombohedra structure as its interior. The formation of this disordered layered phase at the particle surface is electrochemically-favored. It leads to the highest rate capacity ever reported and a superior cycling stability. First-principles calculations further confirm that the excellent electrochemical performance roots in the great chemical/structural stability of such a disordered layered structure, mainly arising from the improved robustness of the oxygen framework by Ti doping. This strategy of constructing the disordered layered phase at the particle surface could be extended to other high-Ni layered transition metal oxides, which will contribute to the enhancement of their electrochemical performance. Received: ((will be filled in by the editorial staff)) Revised: ((will be filled in by the editorial staff))

The dominated hole transport material (HTM) used in state-ofthe-art perovskite solar cells (PSCs) is Spiro-OMeTAD, which needs to be doped to improve its conductivity and mobility. The inevitable instability induced by deliquescent dopants and the necessary oxidation process in air hinders the commercialization of this technology. Here, an alloy strategy using two conjugated polymers with highly similar structures but different crystallinities for dopant-free HTM and high-performance PSCs has been demonstrated. We found that the polymeric packing and crystallinity of a polymer alloy could be regulated finely by blending the polymer PM6 and our developed polymer PMSe, which exhibits a shorter π−π stacking distance due to the improved planarity of the polymer backbone with strong CO•••Se noncovalent interactions. The structure−property relationship of the polymer alloy is investigated by theoretical and experimental analyses. The optimized PSCs using the polymer alloy HTM without any ionic dopants feature an excellent power conversion efficiency of 24.53% and a high open circuit voltage (V OC ) of 1.19 V with much improved stability. This efficiency is much higher than that of the control device using doped Spiro-OMeTAD HTM (PCE = 22.54%). Our work provides a very effective strategy to design and construct dopant-free hole transport materials for highly efficient perovskite solar cells and other applications.

This article reports a self-healing composite polymer electrolyte formed via supramolecular networks for high-performance lithium-ion batteries.

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When testing the electrochemical performance of metal oxide anode for lithium-ion batteries (LIBs), binder played important role on the electrochemical performance. Which binder was more suitable for preparing transition metal oxides anodes of LIBs has not been systematically researched. Herein, five different binders such as polyvinylidene fluoride (PVDF) HSV900, PVDF 301F, PVDF Solvay5130, the mixture of styrene butadiene rubber and sodium carboxymethyl cellulose (SBR+CMC), and polyacrylonitrile (LA133) were studied to make anode electrodes (compared to the full battery). The electrochemical tests show that using SBR+CMC and LA133 binder which use water as solution were significantly better than PVDF. The SBR+CMC binder remarkably improve the bonding capacity, cycle stability, and rate performance of battery anode, and the capacity retention was about 87% after 50th cycle relative to the second cycle. SBR+CMC binder was more suitable for making transition metal oxides anodes of LIBs.