Enabling LiNi_0.88Co_0.09Al_0.03O₂ Cathode Materials with Stable Interface by Modifying Electrolyte with Trimethyl Borate

Abstract

As one of the most promising cathode materials in lithium-ion batteries, nickel-rich cathode materials have been widely studied due to their high specific capacity and high operating voltage to realize the energy density of 300 Wh kg −1 . However, the oxidative decomposition of electrolyte catalyzed by transition metal ions and the crack of secondary particles have brought great challenges to their further development. In order to solve this problem, functionalized electrolyte is often used to stabilize the interface and structure of cathode materials. Herein, it is proposed to add trimethyl borate (TMB) in commercial electrolyte to enhance the interfacial stability of Li-Ni 0.88 Co 0.09 Al 0.03 O 2 cathode material. By adjusting the content of TMB in the electrolyte, it is found that a volume ratio of 10% can achieve the best electrochemical performance. In the voltage range of 3.0−4.3 V, the LiNi 0.88 Co 0.09 Al 0.03 O 2 electrode with the 10% TMB-containing electrolyte can achieve a capacity retention of up to 82% after 300 cycles at 1C rate (1C = 200 mA g −1 ), while the electrode with blank electrolyte is only 61%. Through a systematic analysis toward cycled electrode materials, it is indicated that the cracking degree of secondary particles decreases and a thin, stable, and conductive cathode electrolyte interface film is formed on the electrode with 10% TMB-containing electrolyte. This simple and effective method of improving the interfacial and structural stability of nickel-rich cathode materials via adding TMB in the electrolyte provides a practical strategy for the development of highperformance lithium-ion batteries.

Heterostructured Gel Polymer Electrolyte Enabling Long-Cycle Quasi-Solid-State Lithium Metal Batteries

“…For the fresh GPE-ZIF8-Al 2 O 3 film, the main signal of F 1s located at 687.2 eV is from C–F bonds of PVDF-HFP, and the shoulder peak that appeared at 684.6 eV can be well-attributed to Zn–F bonds, suggesting there is a strong interfacial interaction between the ZIF-8 layer and polymer matrix . The signals of C 1s located at 284.8, 285.6, 286.8, and 289.1 eV are assigned to C–C, C–H, C–O, and CO bonds of ZIF-8 and CA, respectively . Moreover, the single peak of Al 2p of Al 2 O 3 appears at 74.4 eV .…”

“…50 The signals of C 1s located at 284.8, 285.6, 286.8, and 289.1 eV are assigned to C−C, C−H, C−O, and CO bonds of ZIF-8 and CA, respectively. 51 Moreover, the single peak of Al 2p of Al 2 O 3 appears at 74.4 eV. 52 On the one side, after the system is cycled for 1000 h, the main signal of F 1s of GPE-ZIF8-Al 2 O 3 appears at 685.0 eV, and a single peak for Li 1s, meanwhile, rises at 55.6 eV, clearly declaring the formation of LiF.…”

Progress in electrode and electrolyte materials: path to all-solid-state Li-ion batteries

“…In contrast, the cathode prepared via the co-precipitation method delivered only 130.3 mA h g À1 after 100 cycles, with a capacity retention of 63.31%. Xiao et al 81 reported the synthesis of an LiNi 0.88 -Co 0.09 Al 0.03 O 2 cathode with the addition of trimethyl borate (TMB) in the commercial electrolyte, which enhanced the interfacial stability. The LiNi 0.88 Co 0.09 Al 0.03 O 2 electrode with 10% TMB-containing electrolyte could achieve a capacity retention of up to 82% after 300 cycles at 1C rate (1C = 200 mA h g À1 ).…”

Organo-Soluble Decanoic Acid-Modified Ni-Rich Cathode Material LiNi0.90Co0.07Mn0.03O2 for Lithium-Ion Batteries

“…Li-ion batteries are the most popular rechargeable power source for portable electronics and electric vehicles due to their relatively high energy density. − To seek further improvement in energy density, Ni-rich layered oxides such as LiNi x Co y Mn z O 2 ( x ≥ 0.6) are considered to be one of the most promising cathode materials for Li-ion batteries in the near future. − Normally, the higher the Ni content of Ni-rich cathode materials, the higher the capacity. However, the higher Ni content in Ni-rich cathode materials poses more serious challenges in terms of surface slurrying, structural deterioration, interfacial parasitic reaction, and mechanical cracking, in which the structural degradation initiating at the surface and extending to the bulk inherently leads to the sluggish lithium-ion diffusion and, thereby, the worsened electrochemical performance, causing the rapid decay of capacity and potential. , Therefore, surface modification is usually used to improve the cycle stability of Ni-rich cathodes. − On the surface of cathodes, electrolyte decomposition occurs upon cycling because of oxygen evolution of the highly delithiated cathodes to inevitably form a cathode/electrolyte interface (CEI) layer whose properties such as conductivity of Li-ion and stability can influence the strong electrochemical performance of the cathodes. − The nonuniform coverage of the CEI leads to transition metal dissolution and surface structural degradation of the Ni-rich cathode materials because of the uneven lithium transport rate across the interface . In addition, hydrofluoric acid resulting from lithium hexafluorophosphate decomposition attacks the surface to leach transition metal out from the oxide structure, accelerating surface reconstruction .…”