Concurrently Approaching Volumetric and Specific Capacity Limits of Lithium Battery Cathodes via Conformal Pickering Emulsion Graphene Coatings

Abstract

To achieve the high energy densities demanded by emerging technologies, lithium battery electrodes need to approach the volumetric and specific capacity limits of their electrochemically active constituents, which requires minimization of the inactive components of the electrode. However, a reduction in the percentage of inactive conductive additives limits charge transport within the battery electrode, which results in compromised electrochemical performance. Here, we introduce an electrode design that achieves efficient electron and lithium-ion transport kinetics at exceptionally low conductive additive levels and industrially relevant active material areal loadings. Using a scalable Pickering emulsion approach, Ni-rich LiNi 0.8 Co 0.15 Al 0.05 O 2 cathode powders are conformally coated using only 0.5 wt% of solution-processed graphene, resulting in an electrical conductivity that is comparable to 5 wt% carbon black. Moreover, the conformal graphene coating mitigates degradation at the cathode surface, thus This article is protected by copyright. All rights reserved.3 providing improved electrochemical cycle life. The morphology of the electrodes also facilitates rapid lithium-ion transport kinetics, which provides superlative rate capability.Overall, this electrode design concurrently approaches theoretical volumetric and specific capacity limits without tradeoffs in cycle life, rate capability, or active material areal loading.

Graphene/PVDF Composites for Ni-rich Oxide Cathodes toward High-Energy Density Li-ion Batteries

“…These results confirm that the lowdensity CB-containing Ref. electrode with conventional electrode parameters have a limited ρ (≤3.3 g cm −3 ) and hence, a Q vol limit [34,35]. The Q areal and Q vol of NCA electrodes with respect to areal current are depicted in Figure 6e,f, respectively.…”

Graphene collage on Ni-rich layered oxide cathodes for advanced lithium-ion batteries

“…Although direct comparison between the Gr-coated NCA electrodes and their NCM811/CNT electrodes is difficult, our Gr-coated cathodes show meaningful performance metrics, when compared to their data of Q areal = 5-6 mAh cm −2 at~5 mA cm −2 (projected from the corresponding graph at m areal = 43-98 mg cm −2 ) and their less dense electrode architectures (≥200 μm in thickness and ρ ≤ 3.3 g cm −3 ). Recently, we found a similar study on Gr coatings by Hersam's group, who achieved a Gr-coated NCA cathode (m areal ~11 mg cm −2 ) with a high Q vol (~675 mAh cm −3 at 0.1 C) through a Pickering emulsion coating method without CB 44 . Nonetheless, the performance metrics of our Gr-coated, dense NCA cathodes still exceeded their values and the projected Q vol limit (~690 mAh cm −3 ) 37,44 , owing to the conformal Gr coating and highly dense electrode architecture (refer to Supplementary Table 1).…”

“…Recently, we found a similar study on Gr coatings by Hersam's group, who achieved a Gr-coated NCA cathode (m areal ~11 mg cm −2 ) with a high Q vol (~675 mAh cm −3 at 0.1 C) through a Pickering emulsion coating method without CB 44 . Nonetheless, the performance metrics of our Gr-coated, dense NCA cathodes still exceeded their values and the projected Q vol limit (~690 mAh cm −3 ) 37,44 , owing to the conformal Gr coating and highly dense electrode architecture (refer to Supplementary Table 1).…”

Elucidating and Mitigating High‐Voltage Degradation Cascades in Cobalt‐Free LiNiO2 Lithium‐Ion Battery Cathodes

“…[37] Figure 3a shows the galvanostatic profiles of bare LNO (black) and ≈1 wt% graphene-coated LNO (red, G-LNO). The inset SEM image shows that coating the LNO particles with graphene using a Pickering emulsion method [38] yields a surface coating with high conformality (additional SEM images are provided in Figure S15 in the Supporting Information). An abnormal overpotential exceeding 4.1 V, corresponding to the H2-H3 phase transition region, is observed in the G-LNO profile.…”