Cost-Efficient Film-Forming Additive for High-Voltage Lithium–Nickel–Manganese Oxide Cathodes

Abstract

The operating voltage of lithium–nickel–manganese oxide (LiNi0.5Mn1.5O4, LNMO) cathodes far exceeds the oxidation stability of the commercial electrolytes. The electrolytes undergo oxidation and decomposition during the charge/discharge process, resulting in the capacity fading of a high-voltage LNMO. Therefore, enhancing the interphasial stability of the high-voltage LNMO cathode is critical to promoting its commercial application. Applying a film-forming additive is one of the valid methods to solve the interphasial instability. However, most of the proposed additives are expensive, which increases the cost of the battery. In this work, a new cost-efficient film-forming electrolyte additive, 4-trifluoromethylphenylboronic acid (4TP), is adopted to enhance the long-term cycle stability of LNMO/Li cell at 4.9 V. With only 2 wt % 4TP, the capacity retention of LNMO/Li cell reaches up to 89% from 26% after 480 cycles. Moreover, 4TP is effective in increasing the rate performance of graphite anode. These results show that the 4TP additive can be applied in high-voltage LIBs, which significantly increases the manufacturing cost while improving the battery performance.

Insight into the Contribution of the Electrolyte Additive LiBF4 in High-Voltage LiCoO2||SiO/C Pouch Cells

“…Obviously, the cycling performances of pouch cells with 1 and 2% LiBF 4 are similar, which suggests that 1% of LiBF 4 is already sufficient for CEI and SEI film formation, and additional LiBF 4 cannot provide further assistance in the composition and stability of the CEI and SEI films, respectively . Therefore, 1% LiBF 4 was sufficient to ensure the improved cycling performance of pouch cells . The pouch cells in the 1% LiBF 4 -containing electrolyte were called for short as the LiBF 4 system.…”

“…27 Therefore, 1% LiBF 4 was sufficient to ensure the improved cycling performance of pouch cells. 28 The pouch cells in the 1% LiBF 4 -containing electrolyte were called for short as the LiBF 4 system. In order to test whether the impurities can affect the test results, we compared the purity levels of 99 and 99.9% for LiBF 4 , as shown in Figure S2.…”

Construction of Low‐Impedance and High‐Passivated Interphase for Nickel‐Rich Cathode by Low‐Cost Boron‐Containing Electrolyte Additive

“…Besides, the second oxidation peak beyond 4.5 V could be ascribed to the secondary oxidation of PBA or the oxidation of decomposition products of PBA. It should be noted that the planar Pt electrode with smooth surface is not likely to be passivated and thus the responsive current primarily indicates the oxidative reactivity instead of the passivation ability of electrolyte [36] . Thus, the large corresponsive current beyond 4.5 V due to the oxidation of PBA could be mitigated when applied on active NCM811 cathode that can be passivated.…”

Industrial Recycling Process of Batteries for EVs

“…To reduce the consumption of chemicals and energy, reference [36] proposed a simple, green water treatment method to recover graphite from spent LiFePO 4 /graphite batteries. Due to the selfdischarge during battery cycling, the corrosion of hydrofluoric acid, the dissolution of transition metal elements in the positive electrode and the deposition on the negative electrode material, the composition of the SEI film on the waste graphite negative electrode is very complicated [37,38]. Through water treatment, the residual Li in graphite reacts with water to generate H 2 , which can separate the complex SEI film from graphite.…”