Ao Li,Binfang He,Guangchao Jin,Dongmei Liu,Jingbo Chen
Li-rich manganese-based cathode material is expected to be extremely promising for next-generation lithium-ion batteries due to its high specific capacity derived from additional anion redox behavior and low cost of the main element manganese. However, the irreversible release of lattice oxygen results in poor structural stability and inferior electrochemical performances , such as low initial Coulomb efficiency, irreversible capacity decay and serious voltage decay, which limits its commercialization. Herein, a simple strategy to improve the structural stability and electrochemical performances by one-step treatment with triethylamine (TEA) at moderate temperature is reported. TEA was used as a surface treatment reagent to prepare the modified Li-rich manganese-based cathode materials with oxygen vacancies and local structural distortion on the surface. The presence of surface distortion layer and oxygen vacancies inhibits irreversible oxygen release. The result exhibits that initial Coulomb efficiency, rate performance and initial discharge specific capacities are improved. After 100 cycles at a current density of 1 C, the specific capacity of the surface-treated material is 204.3 mAh g -1 (172.6 mAh g -1 for the pristine material), with a capacity retention of 81.26%. Even at a high current density of 10 C, the discharge specific capacity of 139.4 mAh g -1 is still achieved, demonstrating the excellent electrochemical performance. This study provides a simple and effective strategy for constructing special surface structures on Li-rich manganese-based materials to achieve high performance.
This study focuses on suppressing the voltage decay and improving the electrochemical performance of Li-rich and manganese-based (LRM) material by Nb 2 O 5 coating, which is realized by an effective soft-chemical route using a mixture of ethanol and water as co-solvent. After Nb 2 O 5 coating, the resulted material demonstrates superior electrochemical performance as cathode material for LIBs. Particularly, it shows an excellent capacity retention of 98 % after 200 cycles at 1 C (1 C=250 mA g −1 ). Voltage decay within cycling is also obviously suppressed by Nb 2 O 5 coating. Moreover, it exhibits superior rate capacities, delivering 189 and 152 mAh g −1 at high current densities of 2 and 5 C, respectively. The improved electrochemical performance of Nb 2 O 5 coated sample can be attributed to that Nb 2 O 5 can suppress the phase transformation and voltage decay by acting as not only a fast ion conductor to accelerate the lithium ion diffusion at the cathode/electrolyte interface, but also an inert protective layer to reduce the direct contact between the cathode and electrolyte.
危险品化学品经营许可证（带存储）