Synthesis of Highly Dispersible Functionalized Carbon Nanotubes as Conductive Material through a Facile Drying Process for High‐Power Lithium‐ion Batteries

Abstract

Herein, surface‐functionalized carbon nanotubes (CNTs) were successfully synthesized by dry ball milling that facilitates industrial application. The optimal conditions were determined by analyzing the physicochemical characteristics of CNTs, including the content of the carboxyl group (−COOH) induced on the surface of CNTs by co‐existing dry ice based on the ball milling time. Among them, 30 s ball milling (CNTs‐30s) showed a high dispersibility in N‐methyl‐2‐pyrrolidone (NMP) while retaining most carboxyl groups and maintaining the intrinsic high conductivity. In the evaluation of rate capability and 5 C/5 C cyclability applied to the Li1+x(Ni1−y−zCoyMnz)1−xO2 with 60 % Ni (NCM622) cathode, CNTs‐30s showed excellent performance based on a well‐formed conductive network. Regarding improved dispersion properties and electrochemical performance, the optimal surface functionalization conditions, dispersibility, and electrode properties according to the processing time were analyzed; based on these, the correlation with electrochemical performance was confirmed.

LiMn0.8Fe0.2PO4/C Nanoparticles via Polystyrene Template Carburizing Enhance the Rate Capability and Capacity Reversibility of Cathode Materials

“…After 200 cycles at 1C, the discharge capacity of CP 1 -LMFP/C is 115.8 mAh g –1 , the capacity retention rate is 95.5%, and the capacity of sample CP 0 -LMFP/C is 81.7 mAh g –1 , with a 86.5% capacity retention. The improvement of electrochemical performance of CP 1 -LMFP/C materials may be attributed to the decomposition of polystyrene microspheres during carbonization, resulting in finer particles and more uniform distribution of carbon coatings, which optimizes the lithium-ion diffusion channel. , Strikingly, the capacity of CP 0 -LMFP/C decreased and fluctuated slightly in the following dozens of cycles and finally stabilized at about 83 mAh g –1 , which may be due to the slight dissolution of the electrode material and the inevitable side reactions during the cycle, which is common in many electrode materials. , In the following cycles, the stability of capacity can be attributed to the gradual thinning and stability of SEI, , while the CP 1 -LMFP/C cycle is relatively stable, which may be benefited from the uniform coating of carbon to reduce the occurrence of side reactions. To investigate the impact of a composite organic carbon source on the material’s electrochemical capabilities, tests were conducted on the electrical properties of SP 0 -LMFP/C and SP 1 -LMFP/C samples.…”

“…The improvement of electrochemical performance of CP 1 -LMFP/C materials may be attributed to the decomposition of polystyrene microspheres during carbonization, resulting in finer particles and more uniform distribution of carbon coatings, which optimizes the lithiumion diffusion channel. 14,16 Strikingly, the capacity of CP 0 -LMFP/C decreased and fluctuated slightly in the following dozens of cycles and finally stabilized at about 83 mAh g −1 , which may be due to the slight dissolution of the electrode material and the inevitable side reactions during the cycle, which is common in many electrode materials. 43,44 In the following cycles, the stability of capacity can be attributed to the gradual thinning and stability of SEI, 45,46 while the CP 1 -LMFP/C cycle is relatively stable, which may be benefited from the uniform coating of carbon to reduce the occurrence of side reactions.…”

“…Undoubtedly, the issues of low electronic conductivity and sluggish lithium-ion diffusion must be resolved in order to encourage the practical application of olivine structure LiMnPO 4 materials in the cathode of lithium-ion batteries. , In this regard, various strategies have been reported; for example, the electrical conductivity may be efficiently increased by covering carbon-based compounds, ,, reducing the grain size to nanoscale can promote the diffusion of lithium ions, − forming solid solution stable crystal structure with the help of doped ions can reduce the influence of Jahn–Teller effect, − and selecting the crystal plane direction that facilitates lithium-ion diffusion can optimize the reversible capacity of materials. , …”

Research on the Performance Improvement Method for Lithium-Ion Battery in High-Power Application Scenarios

“…For the electrode, materials with poor conductivity, especially the cathode materials, the role of the conductive agent is to form a conductive network to connect the active material particles and provide a fast electron transfer channel. Conductive networks have a very important impact on the performance of lithium-ion batteries [32]. Conductive agents mainly include carbon black, carbon fiber, and carbon nanotubes; Figure 4 shows SEM photos of three different types of conductive agents.…”