Advanced nickel-based composite materials for supercapacitor electrodes Jiangfeng Li, Zhihong Dong, Rui Chen, Qingsheng Wu, Guangtao Zan Abstract: In the era of technological advancement, the increasing energy consumption necessitates sustainable and eco-friendly energy solutions. Supercapacitors (SCs), known for their high capacitance and minimal environmental impact, have become a focus. Nickel-based compounds are prominent due to their high theoretical capacitance, affordability, ecological compatibility, ease of synthesis, and chemical stability. However, challenges such as inadequate rate capability and cycling property hinder their broader applications. This review summarizes the latest advancements in nickel-based composite materials for SC electrodes, discussing their characteristics, fabrication techniques, morphological attributes, and performance enhancement strategies. It also explores the diverse electrochemical properties of SCs, offering insights into the underlying causes. The review concludes with a discussion on prevailing challenges and potential resolutions, anticipating future directions in nickel-based supercapacitor electrode material development. Keywords: Nickel-based electrodes · Composites · Synthetic method · Electrochemical performance · Supercapacitors Introduction: In recent years, the intersection of advancing science and technology with the energy crisis and environmental pollution has increasingly encroached upon the human living environment. This has prompted attention toward novel energy storage devices, including various batteries and supercapacitors. Supercapacitors have higher power density, extended lifespan, enhanced safety, cost-effectiveness, and environmental friendliness compared to batteries. However, their lower energy density limits widespread application. The capacitance characteristics of a supercapacitor are fundamentally influenced by the electrode material, the electrolyte, and the synthesis method. Electrode materials are primarily categorized into two types: electrochemical double-layer capacitive (EDLC) type and pseudocapacitive (PC) type. PC-type materials generally exhibit much higher specific capacitances than EDLC-type materials, making them strong candidates for high-energy-density supercapacitors. Nickel-based materials have garnered extensive interest for their advantages including higher theoretical thermal and chemical stability, lower cost, simpler preparation process, and environmental friendliness. However, inherent challenges such as the irreversibility of Faraday redox reactions, volume expansion/contraction instability, and low conductivity in primitive nickel oxide and nickel hydroxide necessitate further innovation. Research has pivoted toward manipulating the morphology and structure of nickel-based materials through various synthesis methods. Additionally, research has illuminated that the electrochemical properties of nickel-based composites can be notably enhanced through integration of additional materials. This review systematically encapsulates the research progression in nickel-based materials, covering new materials from the perspectives of their properties, preparation methods, and application potentials. It outlines prospective future directions for the development of nickel-based composites as electrodes in supercapacitors.Advanced nickel-based composite materials for supercapacitor electrodes Jiangfeng Li, Zhihong Dong, Rui Chen, Qingsheng Wu, Guangtao Zan Abstract: In the era of technological advancement, the increasing energy consumption necessitates sustainable and eco-friendly energy solutions. Supercapacitors (SCs), known for their high capacitance and minimal environmental impact, have become a focus. Nickel-based compounds are prominent due to their high theoretical capacitance, affordability, ecological compatibility, ease of synthesis, and chemical stability. However, challenges such as inadequate rate capability and cycling property hinder their broader applications. This review summarizes the latest advancements in nickel-based composite materials for SC electrodes, discussing their characteristics, fabrication techniques, morphological attributes, and performance enhancement strategies. It also explores the diverse electrochemical properties of SCs, offering insights into the underlying causes. The review concludes with a discussion on prevailing challenges and potential resolutions, anticipating future directions in nickel-based supercapacitor electrode material development. Keywords: Nickel-based electrodes · Composites · Synthetic method · Electrochemical performance · Supercapacitors Introduction: In recent years, the intersection of advancing science and technology with the energy crisis and environmental pollution has increasingly encroached upon the human living environment. This has prompted attention toward novel energy storage devices, including various batteries and supercapacitors. Supercapacitors have higher power density, extended lifespan, enhanced safety, cost-effectiveness, and environmental friendliness compared to batteries. However, their lower energy density limits widespread application. The capacitance characteristics of a supercapacitor are fundamentally influenced by the electrode material, the electrolyte, and the synthesis method. Electrode materials are primarily categorized into two types: electrochemical double-layer capacitive (EDLC) type and pseudocapacitive (PC) type. PC-type materials generally exhibit much higher specific capacitances than EDLC-type materials, making them strong candidates for high-energy-density supercapacitors. Nickel-based materials have garnered extensive interest for their advantages including higher theoretical thermal and chemical stability, lower cost, simpler preparation process, and environmental friendliness. However, inherent challenges such as the irreversibility of Faraday redox reactions, volume expansion/contraction instability, and low conductivity in primitive nickel oxide and nickel hydroxide necessitate further innovation. Research has pivoted toward manipulating the morphology and structure of nickel-based materials through various synthesis methods. Additionally, research has illuminated that the electrochemical properties of nickel-based composites can be notably enhanced through integration of additional materials. This review systematically encapsulates the research progression in nickel-based materials, covering new materials from the perspectives of their properties, preparation methods, and application potentials. It outlines prospective future directions for the development of nickel-based composites as electrodes in supercapacitors.