Wang Xinzhi,Jiang Qianqian,Zhang Yichi,Yuan Nannan,Tang Jianguo
PLA-1-Al2O3@LNCM synthesized using an efficient and facile plasma-enhanced method exhibits markedly improved capacity retention of 98.6% after 100 cycles, which is much larger than that of LNCM at 80% after 100 cycles. What is more, it also exhibits significantly enhanced cyclicity compared to that of 1-Al2O3@LNCM cathodes prepared using the normal solid state method, which further illustrates the efficiency and superiority of this plasma-enhanced method. More importantly, the rate performance of PLA-1-Al2O3@LNCM is improved because of the better electrolyte storage of the assembled hierarchical architecture of the Al2O3 coating layer according to unimpeded Li+ diffusion from electrode to electrolyte. When cycling at 55°C, the PLA-1-Al2O3@LNCM shows 93.6% capacity retention after 100 cycles, which is greatly enhanced due to the uniform Al2O3 layer. Further, growth of polarization impedance during cycling can be effectively suppressed by the Al2O3 layer, which can further confirm the effect the Al2O3 layer coated on the surface of the LNCM. The enhanced cycling performance and thermal stability illustrates that this facile surface modification, using the plasma-enhanced method, can form an effective structured coating layer, which indicates its prospects as an application in the modification of other electrode materials.
Chen Liang,Lihua Jiang,Shuliang Ye,Zhaoyu Wang,Zesen Wei,Qingsong Wang,Jinhua Sun
Multiple mode calorimetry and C80 micro-calorimeter are used to investigate the impact of cathode and anode on heat generation of lithium ion battery. The thermal behaviors of LiNi x Co y Mn z O 2 /graphite full cell are discussed under normal operating and elevating temperature. Affected by negative entropy change, lithium intercalation presents more exotherms than deintercalation for both electrode materials. The contributions of irreversible and reversible heat to the total heat generation of graphite are evaluated. The phase transitions correlated with voltages and lithium contents are determined. Based on the analysis of half-cell, the effect of two electrodes (with the same capacity) on overall heat generation is nearly the same and anode of full cell plays a key role in charging while cathode dominates in discharging. Thermal behaviors of lithiated graphite and delithiated LiNi x Co y Mn z O 2 , electrolyte and their coexisting system are identified to further explore their influence on battery safety. The breakdown of solid electrolyte interface (SEI) at around 82 °C is considered as a crucial factor affecting the thermal stability of full cell. The oxidation of electrolyte induced by oxygen released from cathode material turns out to be one of the main heat sources. These accurate results are of great significance to improve the existing thermal management system and provide basic data for the prediction of battery performance.
Jun Pan,Huili Peng,Yehao Yan,Yuzhou Bai,Jian Yang,Nana Wang,Shixue Dou,Fuqiang Huang
Polymer solid-state batteries (SSBs) possess the advantages of good interfacial contact, but their application faces low ionic conductivity. Here, three-dimensional (3D) porous composite polymer electrolytes with propylene carbonate plasticizer (3D-PPLLP-CPEs) fabricated effectively, displaying high ionic conductivity even at room temperature. Electrochemical in-situ polymerization of 3D-PPLLP-CPEs occurs during the first discharge process, avoiding safety issues caused by the liquid plasticizer without sacrificing the ionic conductivity of the electrolyte. Besides, the controllable in-situ generated LiF-enriched interface can avoid the Li dendrite growth. To further promote the practical value of SSBs, micro-sized Si@Li 3 PO 4 @C with high initial Coulombic efficiency was adopted to replace lithium foil. The LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM111)//Micro Si@Li 3 PO 4 @C full cell has achieved capacity of 129.1 mAh g −1 at a current density of 0.2 C, with capacity retention of 98.5% after 100 cycles, which is the best performance based on the Si anode in SSBs. Even at the high current density of 2.0 A g −1 , the capacity remains 92.5 mAh g −1 . This design of CPEs and electrodes has paved a new way to construct practical SSBs.
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