Toward the Practical Use of Cobalt-Free Lithium-Ion Batteries by an Advanced Ether-Based Electrolyte

Abstract

The criticality of cobalt (Co) has been motivating the quest for Co-free positive electrode materials for building lithium (Li)-ion batteries (LIBs). However, the LIBs based on Co-free positive electrode materials usually suffer from relatively fast capacity decay when coupled with conventional LiPF 6 -organocarbonate electrolytes. To address this issue, a 1,2-dimethoxyethanebased localized high-concentration electrolyte (LHCE) was developed and evaluated in a Co-free Li-ion cell chemistry (graphite|| LiNi 0.96 Mg 0.02 Ti 0.02 O 2 ). Extraordinary capacity retentions were achieved with the LHCE in coin cells (95.3%), single-layer pouch cells (79.4%), and high-capacity loading double-layer pouch cells (70.9%) after being operated within the voltage range of 2.5−4.4 V for 500 charge/discharge cycles. The capacity retentions of counterpart cells using the LiPF 6 -based conventional electrolyte only reached 61.1, 57.2, and 59.8%, respectively. Mechanistic studies reveal that the superior electrode/electrolyte interphases formed by the LHCE and the intrinsic chemical stability of the LHCE account for the excellent electrochemical performance in the Co-free Liion cells.

Battery technology and recycling alone will not save the electric mobility transition from future cobalt shortages

“…• BT4 includes a revolutionary breakthrough with 'cobalt-free battery cathode technology' 72 , such as lithium-air, lithium-sulfur 73 , and solidstate batteries 74 . We assume that next-generation cobalt-free battery cathode technologies will start penetrating and substituting state-of-the-art battery technologies in 2030 45 .…”

Electrolytes for high-voltage lithium batteries

“…For instance, by substituting LiPF 6 with LiBF 4 , both the electrolyte decomposition and transition metal dissolution can be significantly reduced at high cutoff voltages [84,121]. Similar effects were observed in LiFSI-based LHCEs as well [107]. Therefore, substituting the common LiPF 6 in the state-of-the-art commercial electrolytes with alternative chemically stable conducting salts is considered to be a viable approach to mitigate the severity of transition metal dissolution.…”

“…Because of the extended anodic stability window and the improved SEI/CEI formation ability, HCEs and LHCEs have achieved significantly longer life cycles in high-voltage LIBs than in the conventional LiPF 6 -ogranic carbonate electrolytes (Table 3) [28,[105][106][107]. Meanwhile, because Li bis(fluorosulfonyl)imide (LiFSI) is employed as the conducting salt in most of the LHCEs, which is more chemically and thermally stable than LiPF 6 , the transition metal dissolution and the surface structural degradation of positive electrode materials caused or facilitated by LiPF 6 , are effectively suppressed.…”

Structural regulation chemistry of lithium ion solvation for lithium batteries

“…The excellent performance of LHCE mainly depends on the quality of the anion‐derived SEI, namely, it is related to the degree of anion decomposition 90–92 . Ren et al 48 explored the LHCEs based on lithium bis(fluorosulfonyl)imide (LiFSI) dissolved in dimethyl carbonate (DMC), tetramethylene sulfone (TMS), triethyl phosphate (TEP), and DME solvents with TTE diluent for NCM811 at a high cutoff voltage of 4.4 V, respectively.…”

“…65 Reproduced with permission: 2015, American Association for the Advancement of Science 65 related to the degree of anion decomposition. [90][91][92] Ren et al 48 explored the LHCEs based on lithium bis(fluorosulfonyl)imide (LiFSI) dissolved in dimethyl carbonate (DMC), tetramethylene sulfone (TMS), triethyl phosphate (TEP), and DME solvents with TTE diluent for NCM811 at a high cutoff voltage of 4.4 V, respectively. The DME-based LHCE exhibited the best cycle performance, since the anode surface with higher F and N signals and the least second particle microcracks on the cathode with thin CEI (Figure 2A).…”