Non-flammable Inorganic Liquid Electrolyte Lithium-Ion Batteries

Abstract

Reduced safety of conventional organic electrolyte (OE) lithium-ion batteries (LIBs) during abusive failure conditions pose a technical barrier and the state of uncertainty in the market penetration of electrification of vehicles and stationary storage. To address this, we report nonflammable inorganic liquid electrolyte LiFePO4/Graphite (LFP/G) batteries for commercial high energy/power applications. The inorganic electrolyte (IE) is prepared by solvating the molten LiAlCl4 salts using liquid/gaseous xSO2 (x = 1 to 22 moles SO2, proprietary formulae is used) which shows remarkably high Li+ ion conductivity of 121 mS cm−1 at 22 °C. IE LFP/Li half-cell exhibits outstanding rate capability up to 8 C with the capacity of 74 mAh g−1 at room temperature (RT). For the first time, IE-based commercial prototype LFP/G prismatic cells with the capacity of 1.08 Ah shows ultrahigh longevity (50,000 cycles at 2 C up to 20% residual capacity) with coulombic efficiency of ∼99.99% and constant internal resistance at RT. We also demonstrate depth of discharge up to 0 V for 150 cycles using IE LFP/G cells at RT, which shows comparable cycling stability of cells which are discharged to 2.5 V, in contrast to OE LIBs. Further, the capacity retention is improved by 5% using dip-coating process of positive electrodes.

In situ UV-cured composite electrolytes for highly efficient quasi-solid-state lithium ion batteries with wide temperature range applications

“…8,9 However, using commercial LIBs generally causes safety concerns associated with leakage, burning, and explosion because of the utilization of volatile and ammable liquid electrolytes. [10][11][12][13] Extensive research has demonstrated that the degradation of the LiPF 6 salt and the solid electrolyte interface (SEI) occurs in conventional electrolytes when the operating temperature exceeds 80 °C, and this is accompanied by the decomposition of the solvent to release gases, ultimately resulting in potential re risks. [14][15][16] In contrast, solid-state lithium batteries (SSLBs) utilize solid electrolytes and hence can avoid the aforementioned leakage and combustion hazards.…”

Non-flammable liquid electrolytes for safe batteries

“…The inorganic liquid electrolyte LiAlCl 4 with SO 2 was recently studied in LIBs. 79 This IE displayed an exceptionally high Li + ion conductivity of 121 mS cm À1 at 22 1C, remarkable longevity in LFP//graphite prismatic cells (50 000 cycles reaching 20% of residual capacity) and outstanding discharge and rate capability in LFP//Li half cells up to 8C with a capacity of 74 mA h g À1 .…”

Recent progress in nonflammable electrolytes and cell design for safe Li-ion batteries

“…55 In LIBs, emerging liquified gas electrolytes (LGEs) such as LiAlCl 4 : SO 2 (1 : 3 in molar) and NaBF 4 : NH 3 (1 : 2.5 in molar) are demonstrated to be nonflammable owing to the intrinsic fire-extinguishing properties of inert SO 2 and NH 3 , respectively. 56,57…”