TiO₂ Nanoparticles Assisted LiNbO₃-Coated LiNi_0.8Co_0.1Mn_0.1O₂ Cathode for Lithium-Ion Batteries

Abstract

Ni-rich layered-oxide cathode materials (NCM) are widely recognized for their high capacity and low cost, so that they have become the most promising cathode materials, but the low cycle performance limits their application. Therefore, LiNbO 3 with high Li + conductivity was considered as a coating design for NCM. However, the traditional LiNbO 3 wet coating method adopts an expensive Nb source to be prepared. Herein, we first prepared LiNbO 3 using niobium hydroxide as a Nb source to replace niobium ethoxide and designed a coating strategy that nano-TiO 2 a s a c a r r i e r t o f u l fi l l L i N b O 3 c o a t e d o n L i -Ni 0.8 Co 0.1 Mn 0.1 O 2 (NCM811). The coating strategy promotes Li + conductivity between the cathode particles and helps to shield the contact between the cathode and electrolyte. Moreover, the high specific surface area of nano-TiO 2 was used to control the coating size of LiNbO 3 . At 700 °C sintering temperature, a slight amount of the Ti element was doped into LiNbO 3 to further improve its ionic conductivity. Thus, 1 wt % TiO 2 and LiNbO 3 -modified NCM811 exhibited 25 mAh g −1 capacity improvement (at 1 C, 25 °C) for liquid lithium-ion battery, then showed 24.7 and 49.1 mAh g −1 capacity improvement (0.2 and 1 C, respectively) and higher capacity retention (79.52% vs 58.60% for bare NCM811 after 100 cycles) for PVDF-based solid-state batteries.

Nanostructured LiNi0.8Co0.1Mn0.1O2 with a Hollow Morphology Boosting Cycling Stability as Cathode Materials for Lithium-Ion Batteries

“…Meanwhile, the other pair of redox peaks occurring at 4.2 V is attributed to the redox reaction of Co 3+ /Co 4+ . Notably, the potential interval (Δ V ) between oxidation and reduction peaks indicates the electrode polarization and reversibility of Li ions insertion/extraction . As shown in Figure a,b, the Δ V of the main redox peaks of H-NCM811 is 0.109 V, which is smaller than that of C-NCM811 (0.228 V).…”

B/Al Codoped/Coated Ultra-High Nickel Cobalt-Free Material with Excellent High Voltage/Rate Cycle Stability

“…The LiF at 684.9 eV comes from the decomposition of electrolyte LiPF 6 and the side reaction of HF with the surface residual alkali. The peak at 687.2 eV corresponds to Li x PO y F z /Li x PF y , which are products of LiPF 6 decomposition, and the PVDF at 688.1 eV comes from the electrode binder. , The larger the ratio is of peak areas of LiF and Li x PO y F z /Li x PF y to the peak area of PVDF, the higher is the degree of electrolyte decomposition. It can be clearly seen that the ratio corresponding to the NM90-1%AB material is smaller, indicating that B/Al modification helps suppress the side reactions between the cathode material and the electrolyte.…”

“…Among all coating materials, Li + conductors, such as LiNbO 3 , LiW 2 O 4 , LiBO 2 , LiAlO 2 , and so on, are more favored by researchers because they have better ionic conductivity than that of simple oxides, flurides, and phosphates. − These Li + conductors can form on the surface of the materials by using the harmful alkali residues as reactants, which not only facilitate the Li + insertion/extraction but also provide a physical protective layer to reduce the direct attack of the electrolyte on the electrode surface/interface . Considering that LiBO 2 and LiAlO 2 are excellent Li + conductors, and B and Al have different enhancement mechanisms to electrochemical properties, we adopt a B/Al codoping/coating strategy to synergistically enhance the surface/interface and crystal structure stability of the NM90 material.…”

Na Doping and CeO2 Nanoparticle Surface Modification Enhancing the Li-Rich Li1.2Mn0.54Ni0.13Co0.13O2 Cathode Material for a Lithium-Ion Battery

“…Nevertheless, during cycling, electrode materials are vulnerable to interact with the liquid electrolyte, resulting in structural degradation that moves from the surface into the interior. − This means that surface modification can decrease this structural degradation. Indeed, the surface modification can regulate the thickness of the cathode electrolyte interphase (CEI) and isolate side reactions at the electrode–electrolyte interface by serving as a buffer layer. − To date, many surface modification materials such as AlF 3 , CaF 2 , Li 3 PO 4 , and Li 2 TiO 3 have been used to improve electrochemical performance effectively. − For example, Yuan et al proposed a comodification strategy involving W doping and in situ interfacial-induced preparation of a layered@spinel@Li 2 WO 4 structure, which effectively regulates the lattice oxygen activity, mitigates side reactions, and enhances the structural stability of the oxide. Our group found that codoping K + and PO 4 3– could effectively mitigate capacity and voltage decay, and the modified sample exhibited greater rate performance and cycling stability than the pristine material .…”