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Sodium ions have been successfully doped into LiNi0.8Co0.1Mn0.1O2 (NCM811) by solid phase method. The influences of Na doping on the electrochemical properties of the electrode at high current intensities were studied. The experimental results show that 3% Na modified LiNi0.8Co0.1Mn0.1O2 has superior rate performance and cycling behavior due to the cation mixing is suppressed and the structural stability is enhanced by Na doping. The capacity retention of Li0.97Na0.03Ni0.8Co0.1Mn0.1O2 is 64.33% after 100th cycles at 10 C (1 C = 200 mA · g–1) in the potential range from 2.8 V to 4.3 V, which is greatly higher than the pristine NCM (only 35.01%). Li0.97Na0.03Ni0.8Co0.1Mn0.1O2 also shows excellent rate performance of 140.5 mAh · g–1 at 10 C, and the discharge capacity of 3% Na-NCM is higher than that of the pristine NCM when the current intensity is returned from 10 C to 0.5 C. The analysis of the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements confirm that the Na doping plays an important role in inhibiting the electrochemical polarization of LiNi0.8Co0.1Mn0.1O2 and improving the diffusion of lithium ions.

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Zn-ion hybrid supercapacitors (ZHSCs) are emerging charge storage devices that inherit many of the advantages of supercapacitors and batteries. However, problems such as unsatisfactory cycling stability and low energy density need to be solved urgently, which can be accomplished by developing cathode materials with excellent properties. Herein, we report the development of performance-enhanced ZHSCs obtained by incorporating N and S heteroatoms into orange peel-based hierarchical porous carbon (NS-OPC) to facilitate Zn 2+ adsorption. The results of ex situ photoelectron spectroscopy and X-ray diffraction demonstrated the presence of −OH and Zn 2+ chemisorbed and Zn 4 SO 4 (OH) 6 •5H 2 O during charging and discharging, respectively. Density functional theory calculations show that double doping can promote the chemisorption/desorption kinetics of Zn 2+ and thus promote the electrochemical charge storage of C materials. Impressively, when used to assemble ZHSCs, the device still has an energy density of 53.9 Wh kg −1 , a high power density of 6063.75 W kg −1 , and an 86.2% capacity retention after 10,000 cycles. This study not only provides a reasonable technique for developing superior C-based electrode materials but also contributes to the understanding of the charge storage process in heteroatom-doped C materials.