storage. [2][3][4][5][6][7] Among them, aqueous zinc batteries have aroused extensive interest and attention, which benefits from many advantages of zinc anode, including high theoretical capacity (820 mAh g −1 ), appropriate redox potential (−0.762 V vs the standard hydrogen electrode (SHE)), and intrinsic safety in aqueous system. [8][9][10][11][12][13][14][15][16][17][18][19][20] Inspired by conventional Li + storage reaction, intercalation reaction of transition metal oxides are employed to storage Zn 2+ in the mild aqueous solution. For example, Zn 0.25 V 2 O 5 ·nH 2 O, [9] Prussian blue analogue, [15] VO 2 , [17] MnO 2 , [18] Zn 3 V 2 O 7 (OH) 2 ·2H 2 O, [19] CuV 2 O 6 [20] have been used as cathodes for zinc batteries. However, the hydrated Zn 2+ and H + usually result in large volumetric change and serious structural collapse of these inorganic compounds with the insertion of a large amount of hydrated Zn 2+ , [21][22][23][24][25] showing significant capacity fading and limited cycle life. In recent years, the organic compounds containing carbonyl groups have been employed to store Li + and Na + through reversible coordination reaction (i.e., the CO/C-O-Li + /Na + conversion), and thus many batteries based on organic electrodes were proposed by using monovalent ion (Li + /Na + ) as charge carrier. [26][27][28][29][30][31] Then, it was demonstrated that such coordination reaction can also be used to store divalent ions (e.g., Mg 2+ and Zn 2+ ), which evoked the enthusiasm for developing divalent ion batteries using organic electrode. [32][33][34][35][36][37] Very recently, Chen's group reported the first Zn-organic (C 4 Q//Zn) battery with high energy and long life. [38] Chen and co-workers work indicates that it should be a good choice for building zinc batteries to use organics as the alternative to inorganic host materials to store Zn 2+ . However, many organics with carbonyl groups (CO) and/or their reduced products (C-O-) suffer from the inherent instability and solubility in electrolyte. [39][40][41][42][43] It is well known that the solubility can lead to the crossover of electrode active materials between cathode and anode. As a result, expensive ion exchange membranes generally are required to prevent the crossover. [38] Furthermore, owing to the inevitable presence of H + in mild aqueous electrolyte (e.g., aqueous ZnSO 4 electrolyte generally shows a pH value of 4-5), H + can also react with carbonyl groups of organic compounds before or in parallel with the storage of Zn 2+ , which might aggravate the poor cycle life arising from the inherent The newly emerged aqueous Zn-organic batteries are attracting extensive attention as a promising candidate for energy storage. However, most of them suffer from the unstable and/or soluble nature of organic molecules, showing limited cycle life (≤3000 cycles) that is far away from the requirement (10 000 cycles) for grid-scale energy storage. Here, a new aqueous zinc battery is proposed by using sulfur heterocyclic quinone dibenzo[b,i]thianthrene-5,7,12,1...

The cluster-in-molecule (CIM) local correlation approach with an accurate distant pair correlation energy correction is presented. For large systems, the inclusion of distant pair correlation energies is essential for the accurate predictions of absolute correlation energies and relative energies. Here we propose a simple and efficient scheme for evaluating the distant pair correlation energy correction. The corrections can be readily extracted from electron correlation calculations of clusters with almost no additional effort. Benchmark calculations show that the improved CIM approach can recover more than 99.97% of the conventional correlation energy. By combining the CIM approach with the domain based local pair natural orbital (DLPNO) local correlation approach, we have provided accurate binding energies at the CIM-DLPNO-CCSD(T) level for a test set consisting of eight weakly bound complexes ranging in size from 200 to 1027 atoms. With these results as the reference data, the accuracy and applicability of other electron correlation methods and a few density functional methods for large systems have been assessed.

Zn–organic batteries are attracting extensive attention, but their energy density is limited by the low capacity (<400 mAh g–1) and potential (<1 V vs Zn/Zn2+) of organic cathodes. Herein, we propose a long-life and high-rate Zn–organic battery that includes a poly­(1,5-naphthalenediamine) cathode and a Zn anode in an alkaline electrolyte, where the cathode reaction is based on the coordination reaction between K+ and the CN group (i.e., CN/C–N–K conversion). Interestingly, we find that the discharged Zn–organic battery can recover to its initial state quickly with the presence of O2, and the theoretical calculation demonstrates that the K–N bond in the discharged cathode can be easily broken by O2 via redox reaction. Accordingly, we design a chemically self-charging aqueous Zn–organic battery. Benefiting from the excellent self-rechargeability, the organic cathode exhibits an accumulated capacity of 16264 mAh g–1, which enables the Zn–organic battery to show a record high energy density of 625.5 Wh kg–1.

The p‐type or n‐type redox reactions of organics are being used as the reversible electrodes to build the next‐generation rechargeable batteries with sustainable and tunable characteristics. However, the n‐type organics that store cations generally exhibit low potential (<0.8 V vs. Zn/Zn2+), while the p‐type organics that store anions suffer from limited capacity (<100 mAh g−1). Herein, we demonstrate that bis(phenylamino)phenothiazin‐5‐ium iodide (PTD‐1) containing both n‐type and p‐type redox moieties exhibits a hybrid charge storage mechanism (n/p‐type at low potential, p‐type at high potential). Such a hybrid mechanism combines the advantages of n‐ and p‐type reactions and compensates for the associated drawbacks of each. Accordingly, the aqueous Zn//PTD‐1 full cell shows a high voltage (1.8 Vmaximum or 1.1 Vaverage), a high capacity 188.24 mAh gPTD‐1−1 (achieved at 40 mA g−1), a long‐life and a supercapacitor‐like high power. These results shed new light on the design of advanced organic electrodes.

A fully optimized implementation of the cluster-in-molecule (CIM) local correlation method for faster and more accurate electron correlation calculations of large systems is reported. The speedup comes from the new procedure of constructing virtual localized molecular orbitals of clusters. In the new procedure, Boughton-Pulay projection method is employed instead of a much more expensive Boys localization procedure. In addition, basis set superposition error correction for binding energy calculations and parallelized electron correlation calculations of clusters are now implemented. Benchmark calculations and illustrative applications at the Møller-Plesset perturbation theory, coupled cluster singles and doubles (CCSD), and CCSD with perturbative triples correction levels show that this newly optimized CIM approach is a reliable theoretical tool for electron correlation calculations of various large chemical systems.

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In this article, the cluster-in-molecule (CIM) local correlation approach for periodic systems with periodic boundary condition has been developed, which allows electron-correlation calculations of various crystals computationally tractable. In this approach, the correlation energy per unit cell of a periodic system can be evaluated as the summation of the correlation contributions from electroncorrelation calculations on a series of finite-sized clusters. Each cluster is defined to contain a subset of localized Wannier functions (WFs) (for the occupied space) and projected atomic orbitals (for the virtual space), which can be derived from a periodic Hartree−Fock calculation. Electron-correlation calculations on clusters at second-order Møller−Plesset perturbation theory (MP2) or coupled cluster singles and doubles (CCSD) can be performed with well-established molecular quantum chemistry packages. We perform illustrative calculations at the MP2 and CCSD levels on several types of crystals (neon lattice, carbon monoxide and ammonia crystals, two ionic liquid crystals, and diamond). The results show that CIM is a powerful framework for accurate electron-correlation calculations of crystals.

The generalized energy-based fragmentation (GEBF) method has been applied to investigate relative energies of large water clusters (HO) (n = 32, 64) with the coupled-cluster singles and doubles with noniterative triple excitations (CCSD(T)) and second-order Møller-Plesset perturbation theory (MP2) at the complete basis set (CBS) limit. Here large water clusters are chosen to be representative structures sampled from molecular dynamics (MD) simulations of liquid water. Our calculations show that the GEBF method is capable of providing highly accurate relative energies for these water clusters in a cost-effective way. We demonstrate that the relative energies from GEBF-MP2/CBS are in excellent agreement with those from GEBF-CCSD(T)/CBS for these water clusters. With the GEBF-CCSD(T)/CBS relative energies as the benchmark results, we have assessed the performance of several theoretical methods widely used for ab initio MD simulations of liquids and aqueous solutions. These methods include density functional theory (DFT) with a number of different functionals, MP2, and density functional tight-binding (the third generation, DFTB3 in short). We find that MP2/aug-cc-pVDZ and several DFT methods (such as LC-ωPBE-D3 and ωB97XD) with the aug-cc-pVTZ basis set can provide satisfactory descriptions for these water clusters. Some widely used functionals (such as B3LYP, PBE0) and DFTB3 are not accurate enough for describing the relative energies of large water clusters. Although the basis set dependence of DFT is less than that of ab initio electron correlation methods, we recommend the combination of a few best functionals and large basis sets (at least aug-cc-pVTZ) in theoretical studies on water clusters or aqueous solutions.