Construction of internal electric field to suppress oxygen evolution of Ni-rich cathode materials at a high cutoff voltage

Simultaneous Realization of Multilayer Interphases on a Ni-Rich NCM Cathode and a SiOx Anode by the Combination of Vinylene Carbonate with Lithium Difluoro(oxalato)borate

“…In the SEM analyses, a difference in the surface behavior of the cycled NCM83 cathodes is evident (Figure c,d). In the recovered NCM83 cathode cycled using a standard electrolyte, distinguishing the boundaries between primary particles proved challenging due to the occurrence of severe electrolyte decomposition during cycling . The surface of the recovered NCM83 cathode controlled by using the VL additive was relatively clean even after 100 cycles, which may be attributed to the prevention of parasitic reactions through the formation of CEI layers.…”

Review on Oxygen Release Mechanism and Modification Strategy of Nickel-Rich NCM Cathode Materials for Lithium-Ion Batteries: Recent Advances and Future Directions

“…The whole process of lattice oxygen release can be divided into two processes: (1) the Li–O and TM–O bonds could be easily broken by the oxygen under-coordinated at the surface to form new O–O chemical bonds, resulting in the loss of surface oxygen and leaving oxygen vacancies; (2) the internal O 2– migrates to the surface through the surface oxygen vacancies. During the cycling process, O 2– gradually expanded into the host phase region, forming continuous lattice oxygen migration in the lattice, leading to oxygen skeleton instability and oxygen precipitation, and may even lead to phase change and electrolyte decomposition. , In addition, the evolution of oxygen precipitated from nickel-rich NCM will induce phase transition, which inevitably triggers undesirable migration of transition metals and structural degradation and exacerbates the formation of oxygen vacancies . Panels h and I of Figure show the process of irreversible precipitation of oxygen in the lattice with voltage change under overcharge conditions.…”

Thermodynamically Stable Dual‐Modified LiF&FeF3 layer Empowering Ni‐Rich Cathodes with Superior Cyclabilities

“…[11,12] Meanwhile, O α− (α<2) in the subsurface gradually migrate to the outermost layer through oxygen vacancies under the external electrical field, further expanding outward from the interior structure during the long cycle, resulting in continuous oxygen loss. [13,14] The oxygen released, comprising oxygen (O 2 ) and O α− radicals with highly oxidative, might quickly break down the carbonateelectrolyte and generate a thick cathode electrolyte interface (CEI), reducing battery cycling. Furthermore, it has been established that lithium impurities (such as lithium hydroxide, LiOH and lithium carbonate, Li 2 CO 3 ) may break down at ∼3.9 voltages, releasing singlet oxygen and carbon dioxide (CO 2 ), the latter presumably causing electrolyte degradation and increased CO 2 .…”

“…In the delithiated state, the Li/Ni exchange energy of NCM@LFF3 is higher than that of NCM811 (Figure 6m). [13,64] It demonstrates that the energy barrier for Ni 2+ migration to the Li-layer is higher in NCM@LFF3 than in NCM811 (Figure S21, Supporting Information). Furthermore, the LiF&FeF 3 dual-modified coating efficiently prevents transition metal dissolution and inhibits undesired phase changes caused by the electrolyte.…”