Specific Electrolyte for High-Voltage Lithium-Ion Battery {>4.35V NCM (Ni<80%) + Graphite}, 200 g/bottle, CHVLIBSEMNCMG

Operating a high-voltage lithium-ion cell with a medium-to-high nickel NCM cathode (such as NCM523, NCM622, or NCM711, where {Ni} < 80%) charged to >4.35 V (typically up to 4.4 V–4.5 V) paired with a Graphite anode requires a carefully formulated electrolyte. At these elevated cutoff voltages, standard carbonate electrolytes undergo accelerated oxidative decomposition, leading to transition-metal dissolution (Ni^{2+}, Co^{2+}, Mn^{2+}), reactive oxygen release from the lattice, and continuous structural micro-cracking at the secondary particle boundaries.

The recommended electrolyte recipe are shown below: (1) Salt Framework: The primary salt is 1.0 M to 1.2 M LiPF6 (essential for passivating the aluminum current collector against pitting corrosion at potentials >4.3 V). The secondary salt additive can be 0.1 M to 0.2 M Lithium bis(fluorosulfonyl)imide (LiFSI) to enhance ionic conductivity and assist in forming a robust, inorganic-rich Solid Electrolyte Interphase (SEI) on the graphite anode. (2) Solvent Architecture: (i) Core Solvents: Ethylene Carbonate (EC) + Ethyl Methyl Carbonate (EMC) + Dimethyl Carbonate (DMC). A balanced weight ratio like EC:EMC:DMC = 2:4:4 or a restricted-EC formulation (EC:EMC = 3:7) minimizes excessive solvent oxidation while maintaining excellent separator wetting and low bulk viscosity. Incorporation of a minor fraction (e.g., 5–15 wt.%) of a fluorinated ether (such as TTE or TFEE) or a fluorinated carbonate (like ETFEC or MHFPC) to suppress free solvent activity and widen the electrochemical stability window. (3) Essential Functional Interphase Additives: (i) 1.5 wt% to 2.0 wt% Fluoroethylene Carbonate (FEC): Vital for building a dense, elastic, LiF-rich SEI on the graphite anode that prevents exfoliation and continuous solvent reduction. (ii) 1.0 wt% Lithium difluoro(oxalato)borate (LiDFOB) or LiBOB: Forms a stable, protective boron- and oxalate-based passivating film (CEI) on the high-voltage NCM surface, mitigating transition-metal dissolution and surface phase transitions. (iii) 0.5 wt% Tris(trimethylsilyl) phosphite (TMSPi) or Succinonitrile (SN): Scavenges trace hydrofluoric acid (HF) and moisture, neutralizing acid-catalyzed degradation and coordinating with dissolved transition-metal ions to prevent them from poisoning the anode SEI.

Notes: Please store the specific LIB electrolyte in the glovebox due to its sensitivity to humidity.

References: 

1. S. Klein, et al. Understanding the Outstanding High-Voltage Performance of NCM523||Graphite Lithium Ion Cells after Elimination of Ethylene Carbonate Solvent from Conventional Electrolyte, Adv. Energy Mater., 2021, 11, 2003738
2. S. Klein, et al. On the Beneficial Impact of Li2CO3 as Electrolyte Additive in NCM523 ∥ Graphite Lithium Ion Cells Under High-Voltage Conditions, Adv. Energy Mater., 2021, 11, 2003756