LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)is the most promising cathode for high-energy Li-ion batteries,despite its poor cycling stability that originates from the reactions that occur with the electrolyte.Herein,to sol...LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)is the most promising cathode for high-energy Li-ion batteries,despite its poor cycling stability that originates from the reactions that occur with the electrolyte.Herein,to solve this interfacial issue,a facile electrolytic electrochemical polymerization process was introduced in this paper,and a uniform conductive electrolyte interface(polyaniline)was successfully constructed on the surface of the NCM811 porous electrode(PANI-NCM),which facilitated the charge transfer during charge/discharge.The side reactions at the interface between the cathode and the electrolyte are suppressed,and thereby,the cycling performance and rate capability are considerably improved.PANI-NCM delivers an initial capacity of 157.2 mAh·g^(-1)as well as excellent cyclability(capacity retention of 88%after 500 cycles at 2C),whereas the capacity of the bare NCM811 has dropped to 31.3 mAh·g^(-1).In addition,polypyrrole and polythiophene also can be formed through electrolytic electrochemical polymerization process,which provides a practicable tactic to modify the interfacial stability of cathodes for high-energy Li-ion batteries.展开更多
High-capacity Li-rich cathode materials can significantly improve the energy density of lithium-ion batteries, which is the key limitation to miniaturization of electronic devices and further improvement of electrical...High-capacity Li-rich cathode materials can significantly improve the energy density of lithium-ion batteries, which is the key limitation to miniaturization of electronic devices and further improvement of electrical-vehicle mileage. However, severe voltage decay hinders the further commercialization of these materials. Insights into the relationship between the inherent structural stability and external appearance of the voltage decay in high-energy Li-rich cathode materials are critical to solve this problem. Here, we demonstrate that structural evolution can be significantly inhibited by the intentional introduction of certain adventive cations （such as Ni2~） or by premeditated reservation of some of the original Li~ ions in the Li slab in the delithiated state. The voltage decay of Li-rich cathode materials over 100 cycles decreased from 500 to 90 or 40 mV upon introducing Ni2~ or retaining some Li~ ions in the Li slab, respectively. The cations in the Li slab can serve as stabilizers to reduce the repulsion between the two neighboring oxygen layers, leading to improved thermodynamic stability. Meanwhile, the cations also suppress transition metal ion migration into the Li slab, thereby inhibiting structural evolution and mitigating voltage decay. These findings provide insights into the origin of voltage decay in Li-rich cathode materials and set new guidelines for designing these materials for high-energy-density Li-ion batteries.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52172227 and Z190010)。
文摘LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)is the most promising cathode for high-energy Li-ion batteries,despite its poor cycling stability that originates from the reactions that occur with the electrolyte.Herein,to solve this interfacial issue,a facile electrolytic electrochemical polymerization process was introduced in this paper,and a uniform conductive electrolyte interface(polyaniline)was successfully constructed on the surface of the NCM811 porous electrode(PANI-NCM),which facilitated the charge transfer during charge/discharge.The side reactions at the interface between the cathode and the electrolyte are suppressed,and thereby,the cycling performance and rate capability are considerably improved.PANI-NCM delivers an initial capacity of 157.2 mAh·g^(-1)as well as excellent cyclability(capacity retention of 88%after 500 cycles at 2C),whereas the capacity of the bare NCM811 has dropped to 31.3 mAh·g^(-1).In addition,polypyrrole and polythiophene also can be formed through electrolytic electrochemical polymerization process,which provides a practicable tactic to modify the interfacial stability of cathodes for high-energy Li-ion batteries.
文摘High-capacity Li-rich cathode materials can significantly improve the energy density of lithium-ion batteries, which is the key limitation to miniaturization of electronic devices and further improvement of electrical-vehicle mileage. However, severe voltage decay hinders the further commercialization of these materials. Insights into the relationship between the inherent structural stability and external appearance of the voltage decay in high-energy Li-rich cathode materials are critical to solve this problem. Here, we demonstrate that structural evolution can be significantly inhibited by the intentional introduction of certain adventive cations （such as Ni2~） or by premeditated reservation of some of the original Li~ ions in the Li slab in the delithiated state. The voltage decay of Li-rich cathode materials over 100 cycles decreased from 500 to 90 or 40 mV upon introducing Ni2~ or retaining some Li~ ions in the Li slab, respectively. The cations in the Li slab can serve as stabilizers to reduce the repulsion between the two neighboring oxygen layers, leading to improved thermodynamic stability. Meanwhile, the cations also suppress transition metal ion migration into the Li slab, thereby inhibiting structural evolution and mitigating voltage decay. These findings provide insights into the origin of voltage decay in Li-rich cathode materials and set new guidelines for designing these materials for high-energy-density Li-ion batteries.
