Ni-MOF-INTEGRATED FUNCTIONAL SEPARATORS FOR LITHIUM-ION BATTERIES

Kurzfassung

In recent years, Metal−organic frameworks (MOFs) have emerged as promising advanced materials for electrochemical energy storage and conversion systems due to their highly ordered and tunable compositions, excellent thermal stability, ultra-high specific surface area, adjustable porosity and structures [1]. In the field of electrochemical energy storage devices, rechargeable lithium-ion batteries (LIBs) have become the most popular and widely used in portable electronics, electric vehicles, aerospace and many other applications due to their remarkable performance. However, with the advancement and demand of modern energy technologies, LIBs are facing several challenges in meeting the expectations of current customers [2]. Along with the cathode, anode and electrolyte, the separator is one of the most important components for LIBs which prevents the physical contact between the cathode and anode while facilitating the movements of Li+ ions. However, typical polymer separators suffer from poor electrolyte wettability, inhomogeneous pore distribution and insufficient thermal stability, which stimulates the need for novel functional separators [3]. In this work, Ni-MOF-74 nanomaterials have been synthesized by hydrothermal process and integrated with glass fiber (GF) separator for LIB applications in the framework of PHOENIX project (grant agreement no. 101103702). Microstructural and morphological analysis have been performed using sophisticated XRD, SEM and EDX studies. Afterwards, the electrochemical LIB performance of this Ni-MOF integrated GF-separators have been initially conducted using CR2032 type half– coin cells composed of synthesized LiNi0.6Mn0.2Co0.2O2 (NMC622) active cathode material, pure Li-anode and 1 M LiPF6 in EC/DMC (50/50) (v/v) electrolyte. The Ni-MOF integrated GF-separators have been fabricated using different wt% such as 5 wt%, 10 wt% and 15 wt% of Ni-MOF. The capacity retention, cycling stability and internal resistance have been evaluated via galvanostatic charge-discharge (GCD) testing in the voltage range of 2.7 V to 4.2 V at C/10 and electrochemical impedance spectroscopy (EIS) analysis. Ni-MOF-74 (5 wt%) integrated GFseparator based LIB shows excellent capacity retention after 50 cycles offering capacity of 96.6 mAh/g in the 1st cycle and reduced to 94.1 mAh/g after 50 cycles, which indicates the stable performance of Ni-MOF-integrated separator-based LIBs compared to pure GF-based LIBs (Figure 1). Finally, the Ni-MOF integrated GF separator also improves the cyclic stability and electrochemical performance of the full cell LIB composed of NMC811 cathode and Gr/SiOx anode over 200 cycles at C/3. Overall, this work demonstrates the potential future of MOFintegrated functional separators in battery technologies and energy storage systems.