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A Nanostructured Cathode Material with Varied Chemical Composition for High Energy Density Sodium Ion Batteries
A Nanostructured Cathode Material with Varied Chemical Composition for High Energy Density Sodium Ion Batteries
Sunday, October 11, 2015: 15:40
Phoenix West (Hyatt Regency)
Lithium batteries currently dominate the secondary battery market because of their high energy and good power density.[1] Despite their feasibility, the mass production of such large-scale batteries would likely contribute to the future exhaustion of limited lithium resources. This concern has led us to look for alternative systems to replace current lithium-related chemistries. Because of sodium’s abundance in nature, sodium-based rechargeable batteries have recently received intensive attentions [2]Our prior works36,37, we suggested that the nanorod-structured full concentration gradient materials are beneficial in performing outstanding electrochemical properties and excellent safety in lithium-ion batteries system, because the dense rod assembly could minimize surface area contacting with electrolyte.[3] We introduce a new concept: a radially aligned hierarchical columnar structure (RAHC) in spherical particles with varied chemical composition from the inner end (Na[Ni0.75Co0.02Mn0.23]O2) to the outer end (Na[Ni0.58Co0.06Mn0.36]O2) of the structure.Using this concept, we suggest that an electrochemical reaction based on Ni2+/3+/4+ is readily available to deliver a high discharge capacity of 157 mAh (g-oxide)-1 (15 mA g-1), an excellent capacity retention of 80% (125 mAh g-1) during 300 cycles in combination with a hard carbon anode, and a reasonable rate capability of 132.6 mAh g-1 (1500 mA g-1, 10 C-rate). In addition, the RAHC electrode exhibits good temperature performance even at -20°C. The chemistry of the RAHC material, which utilizes the Ni redox reaction and minimizes the surface area contacting corrosive electrolyte, is responsible for the excellent electrochemical properties and the satisfactory thermal stability, which exhibits a main exothermic reaction at 293.5oC with low heat generation.
References
(1) Scrosati, B. & Garche, J. Lithium batteries: status, prospects and future. J. Power Sources 195, 2419 (2010).
(2) Stevens, D. A., Dahn, J. R. High capacity anode materials for rechargeable sodium-ion batteries. J. Electrochem. Soc. 147(4), 1271 (2000).
(3) Sun, Y.-K. et al. Nanostructured high-energy cathode materials for advanced lithium batteries. Nat. Mater. 11, 942 (2012).