Coating of a Novel Lithium-Containing Hybrid Oligomer Additive on Nickel-Rich LiNi_0.8Co_0.1Mn_0.1O₂ Cathode Materials for High-Stability and High-Safety Lithium-Ion Batteries

Abstract

In this study, we synthesized a Li-containing "BTJ-L" hybrid oligomerobtained through polymerization of bismaleimide (BMI) with a polyether monoamine (i.e., Jeffamine-M1000, JA), trithiocyanuric acid (TCA), and LiOHand coated it as an additive in various amounts (0.5−2 wt %) onto the surface of a Ni-rich LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathode active material, forming BTJ-L@NCM811 electrodes for lithiumion batteries (LIBs). Relative to CR2032 coin-type cells incorporating a pristine NCM811 electrode, the cells with the 1 wt % BTJ-L@NCM811 electrode demonstrated a slightly higher initial discharge capacity (173 mAh g −1 vs171 mAh g −1 ) and higher values of average Coulombic efficiency, CE avg (99.5% vs98.9%) and capacity retention, CR (86.1% vs72.9%) after 100 cycles at 1C. Electrochemical impedance spectroscopy revealed that the decrease in the charge transfer resistance (R ct : 46.7 Ω vs171.1 Ω) and the superior Li + ion diffusivity (D Li + : ∼1.09 × 10 −12 cm 2 s −1 vs ∼1.61 × 10 −13 cm 2 s −1 ) of the cells incorporating the BTJ-L@NCM811 electrode after cycling at 1C could be attributed to the excellent wettability toward the electrolyte and the extra Li + ions contributed by the hybrid BTJ-L oligomer additive. Therefore, the BTJ-L oligomer coating layer functioned much like an artificial cathode electrolyte interphase (CEI) layer, impairing the dissolution of transition metals (TMs) from the cathode materials into the carbonate-based electrolytes. Furthermore, in situ microcalorimetry manifested that the total exothermic heat generation (Q t ) of the coin cells containing the 1 wt % BTJ-L@NCM811 electrode operating at 1C in isothermal modes (35 and 55 °C) during the charging process was dramatically lower (by ca. 45%) relative to that of the cells incorporating the pristine NCM811 electrode. On the basis of an ARC-HWS analysis, the delithiated pristine NCM811 electrode shows thermal reactivity with the electrolyte at a much earlier stage in comparison to the 1 wt % BTJ-L@NCM811 counterpart (843 min vs 1039 min) between 171 and 192 °C. Thus, Ni-rich NCM811 cathode materials coated with trace amounts (i.e., 1 wt %) of the BTJ211-L1 hybrid oligomer additives displayed both enhanced electrochemical performance and remarkably improved thermal stability. Accordingly, this Li-containing BTJ-L hybrid oligomer appears to be a great candidate material for coating high-Ni oxide cathode materials to enhance the safety and electrochemical performance of LIB cells.

Concerted Effect of Ion- and Electron-Conductive Additives on the Electrochemical and Thermal Performances of the LiNi0.8Co0.1Mn0.1O2 Cathode Material Synthesized by a Taylor-Flow Reactor for Lithium-Ion Batteries

“…Moreover, we presented the comparative cycling performance of the bare NCM811 ( Q sp,ini dchg : ∼177.2 mA h g –1 ), NCM811@Li-BTJ ( Q sp,ini dchg : ∼176.1 mA h g –1 ) and NCM811@Li-BTJ + 1% PDA-VGCF ( Q sp,ini dchg : ∼172.6 mA h g –1 ) electrode-based cells at 1C/1C and 45 °C, as displayed in Figure S5b. After 100 cycles, the NCM811@Li-BTJ + 1% PDA-VGCF//Li cells delivered high CR and CE avg values of 85.5 and 99.0%, superior to those of the NCM811@LI-BTJ (77.47 and 99.1%) and bare NCM811 (73.6% and 98.7%) counterparts; as compared in Figure S5a,b, the cells’ initial discharge specific capacities at 45 °C were higher than those at RT since the elevated temperature accelerated charge transfer kinetics . When compared to the RT, however, the capacity fading was faster at the elevated temperature upon cycling owing to the electrolyte decomposition, which also induced the dissolution of TMs and unwanted side reactions.…”

Stabilizing Commercial LiMn2O4 Cathode by Constructing Protective Saccharin Coating

“…Correspondingly, the peak area ratio of CO (at 531.7 eV) and Mn–O is 0.41 for 1.0S-LMO, higher than that for P-LMO (0.39), indicative of the presence of SAC coating on the surface of LMO. , In the Mn 2p spectra of the 1.0S-LMO (Figure c), the 2p 1/2 peak at 641.3 eV and 2p 3/2 peak at 653.5 eV represent Mn 3+ oxidation state, while the 2p 1/2 peak at 642.7 eV and 2p 3/2 peak at 654.3 eV are associated with the Mn 4+ oxidation state. Compared with P-LMO, the binding energy of Mn 2p for 1.0S-LMO shifts slightly to a higher value, denoting the enhanced stability of Mn 4+ /Mn 3+ after the SAC modification . In the S 2p spectrum of 1.0S-LMO, the peaks at 168.7 eV (S 2p 3/2 ) and 169.9 eV (S 2p 1/2 ) are attributable to the −SO 2 – groups of SAC , (Figure d).…”

“…Compared with P-LMO, the binding energy of Mn 2p for 1.0S-LMO shifts slightly to a higher value, denoting the enhanced stability of Mn 4+ /Mn 3+ after the SAC modification. 21 In the S 2p spectrum of 1.0S-LMO, the peaks at 168.7 eV (S 2p 3/2 ) and 169.9 eV (S 2p 1/2 ) are attributable to the −SO 2 − groups of SAC 22,23 (Figure 3d). In the N 1s 4a).…”

Theoretical Revelation and Experimental Verification Synergistic Electronic Interaction of V-Doped RuNi as an Efficient Bifunctional Electrocatalyst for Overall Water Splitting

“…The long-term stability of RuNiVO was determined by time potentiometry. 68 When the current density is 10 mA cm −2 , the catalytic performance of the RuNiVO catalyst is very stable after 48 h, and the overpotential is slightly reduced (Figure 7d). It can be observed that the composition and distribution of elements in RuNiVO remain nearly unchanged before and after the stability test, as shown in Figure S30.…”

“…Hence, the enhanced reaction kinetics of RuNiVO comes down to the generation of a rapid electron transfer pathway facilitated by V doping and oxidation treatment, leading to an increased charge transfer rate. The long-term stability of RuNiVO was determined by time potentiometry . When the current density is 10 mA cm –2 , the catalytic performance of the RuNiVO catalyst is very stable after 48 h, and the overpotential is slightly reduced (Figure d).…”