Li-richl ayered oxides with high capacity are expected to be the next generation of cathode materials. However,t he irreversible and sluggish anionic redox reaction leads to the O 2 loss in the surface as well as the capacity and voltage fading.I nt he present study,asimple gas-solid treatment with ferrous oxalate has been proposed to uniformly coat at hin spinel phase layer with oxygen vacancy and simultaneously realize Fe-ion substitution in the surface.T he integration of oxygen vacancy and spinel phase suppresses irreversible O 2 release,p revents electrolyte corrosion, and promotes Li-ion diffusion. In addition, the surface doping of Fe-ion can further stabilizet he structure.A ccordingly,t he treated Feox-2 %c athode exhibits superior capacity retention of 86.4 %a nd 85.5 %a t1Ca nd 2C to that (75.3 %a nd 75.0 %) of the pristine sample after 300 cycles,r espectively. Then, the voltage fading is significantly suppressed to 0.0011 V per cycle at 2Cespecially.T he encouraging results may play asignificant role in paving the practical application of Li-rich layered oxides cathode.
Nickel‐rich layered transition metal oxides are considered as promising cathode candidates to construct next‐generation lithium‐ion batteries to satisfy the demands of electrical vehicles, because of the high energy density, low cost, and environment friendliness. However, some problems related to rate capability, structure stability, and safety still hamper their commercial application. In this Review, beginning with the relationships between the physicochemical properties and electrochemical performance, the underlying mechanisms of the capacity/voltage fade and the unstable structure of Ni‐rich cathodes are deeply analyzed. Furthermore, the recent research progress of Ni‐rich oxide cathode materials through element doping, surface modification, and structure tuning are summarized. Finally, this review concludes by discussing new insights to expand the field of Ni‐rich oxides and promote practical applications.
The interface structure of the electrode is closely related to the electrochemical performance of lithium‐metal batteries (LMBs). In particular, a high‐quality solid electrode interface (SEI) and uniform, dense lithium plating/stripping processes play a key role in achieving stable LMBs. Herein, a LiF‐rich SEI and a uniform and dense plating/stripping process of the electrolyte by reducing the electrolyte concentration without changing the solvation structure, thereby avoiding the high cost and poor wetting properties of high‐concentration electrolytes are achieved. The ultra‐low concentration electrolyte with an unchanged Li+ solvation structure can restrain the inhomogeneous diffusion flux of Li+, thereby achieving more uniform lithium deposition and stripping processes while maintaining a LiF‐rich SEI. The LiIICu battery with this electrolyte exhibits enhanced cycling stability for 1000 cycles with a coulombic efficiency of 99% at 1 mA cm–2 and 1 mAh cm–2. For the LiIILiFePO4 pouch cell, the capacity retention values at 0.5 and 1 C are 98.6% and 91.4%, respectively. This study offers a new perspective for the commercial application of low‐cost electrolytes with ultra‐low concentrations and high concentration effects.
Li- and Mn-rich layered oxide (LMR) materials are a promising candidates for next-generation Li-ion battery (LIB) anode materials because of their high specific capacity. However, their low initial Coulombic efficiency, voltage decay, and irreversible phase transition during cycling are the fatal drawbacks of LMR materials. This work reports on a cobalt-free LMR material composed of primary particles with a boron-induced exposed long- strip-like {010} plane. Because of this unique structure, the long strip-like cathode exhibits excellent electrochemical performance with a discharge capacity of 202 mAh g–1 at 1 C and a retention rate of 95.2% after 200 cycles. In addition, it is found that this long strip-like structure can modulate the redox of oxygen and enhance the reversibility. The irreversible phase transition process from the layered to a spinel and then to a rock-salt phase during cycling is also significantly suppressed. This work provides a feasible method for regulating the exposed {010} plane and a new idea for the structural design of LMR materials.
Li-richl ayered oxides with high capacity are expected to be the next generation of cathode materials. However,t he irreversible and sluggish anionic redox reaction leads to the O 2 loss in the surface as well as the capacity and voltage fading.I nt he present study,asimple gas-solid treatment with ferrous oxalate has been proposed to uniformly coat at hin spinel phase layer with oxygen vacancy and simultaneously realize Fe-ion substitution in the surface.T he integration of oxygen vacancy and spinel phase suppresses irreversible O 2 release,p revents electrolyte corrosion, and promotes Li-ion diffusion. In addition, the surface doping of Fe-ion can further stabilizet he structure.A ccordingly,t he treated Feox-2 %c athode exhibits superior capacity retention of 86.4 %a nd 85.5 %a t1Ca nd 2C to that (75.3 %a nd 75.0 %) of the pristine sample after 300 cycles,r espectively. Then, the voltage fading is significantly suppressed to 0.0011 V per cycle at 2Cespecially.T he encouraging results may play asignificant role in paving the practical application of Li-rich layered oxides cathode.
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