| 1. |
- Cuevas, Ignacio, et al.
(författare)
-
Li7La3Zr2O12 interface functionalization via boric acid treatment : A step to contact improvement
- 2024
-
Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 656
-
Tidskriftsartikel (refereegranskat)abstract
- Realization of a functional surface layer of lithium metaborate at the interface of garnet-type lithium lanthanum zirconium oxide (LLZO) electrolyte pellets is achieved via a mild, scalable solution-based route employing boric acid to transform and remove detrimental Li2CO3 typically formed on LLZO during exposure to humid air. The effects of this boric acid treatment are evaluated by systematic morphological and structural characterization of LLZO pellets that were subjected to different conditions. Surface-sensitive analyses via X-ray photoelectron spectroscopy, combined with in situ Ar-ion etching and reflection electron energy loss spectroscopy (REELS) measurements, are purposely employed to probe the extent and efficacy of resulting LiBO2 in removing Li2CO3 and protecting the modified LLZO surface from unwanted carbonation that disrupts its interfacial Li-ion conductivity. This key aspect has been corroborated by an aimed comparison of the different LLZO surface energy bandgap values extracted from the REELS measurements, which provides further insight into the actual impact of Li2CO3 and its replacement with a beneficial, ionically conducting LiBO2 layer. The latter substantially improves the surface adhesion of the modified LLZO pellets to molten lithium without introducing metallic-like species and provides an overall reduced impedance by unlocking the interfacial Li-ion conduction otherwise severely hampered by Li2CO3.
|
|
| 2. |
- Elbouazzaoui, Kenza, et al.
(författare)
-
Ionic transport in solid-state composite poly(trimethylene carbonate)-Li6.7Al0.3La3Zr2O12 electrolytes : The interplay between surface chemistry and ceramic particle loading
- 2023
-
Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 462
-
Tidskriftsartikel (refereegranskat)abstract
- The ionic transport in solid-state composite electrolytes based on poly(trimethylene carbonate) (PTMC) with LiTFSI salt and garnet-type ion-conducting Li6.7Al0.3-La3Zr2O12 (LLZO) ceramic particles is here investigated for a range of different compositions. Positive effects on ionic conductivity have previously been reported for LLZO incorporated into poly(ethylene oxide) (PEO), but the origin of these effects is unclear since the inclusion of particles also affects polymer crystallinity. PTMC is, in contrast to PEO, a fully amorphous polymer, and therefore here chosen for the design of a more straight-forward composite electrolyte (CPE) system to study ionic transport. With LLZO loadings ranging from 5 to 70 wt%, the CPE with 30 wt% of LLZO exhibits the highest ionic conductivity with a cationic transference number of 0.94 at 60 degrees C. This is significantly higher than for the pristine PTMC polymer electrolyte. Generally, low to moderate LLZO loadings display a gradual increase of the ionic conductivity, transference number and also of the polymer-cation coordination number. The combined contributions of ionic transport along polymer-ceramic interfaces and Lewis acid-base interaction between the LLZO particles and the LiTFSI salt can explain this enhancement. With loadings of LLZO above 50 wt%, a detrimental effect on the ionic conductivity was however observed. This could be explained by agglomeration of ceramic particles, and by a partial coverage of LLZO particles with a Li2CO3 layer. Consequently, inner polymer-particle interfaces become more resistive, and Li+conduction is prevented along interfacial pathways. The presence of Li2CO3 has more detrimental impact at higher LLZO loadings, since inter-particle connectivity will be hampered, and this is vital for efficient ionic transport. This suggests that there is an interplay between the LLZO particle surface chemistry with its loading, which ultimately controls the Li-ion transport.
|
|
| 3. |
- Nkosi, Funeka P., et al.
(författare)
-
Garnet-Poly(epsilon-caprolactone-co-trimethylene carbonate) Polymer-in-Ceramic Composite Electrolyte for All-Solid-State Lithium-Ion Batteries
- 2021
-
Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 4:3, s. 2531-2542
-
Tidskriftsartikel (refereegranskat)abstract
- A composite electrolyte based on a garnet electrolyte (LLZO) and polyester-based co-polymer (80:20 epsilon-caprolactone (CL)-trimethylene carbonate, PCL-PTMC with LiTFSI salt) is prepared. Integrating the merits of both ceramic and co-polymer electrolytes is expected to address the poor ionic conductivity and high interfacial resistance in solid-state lithium-ion batteries. The composite electrolyte with 80 wt % LLZO and 20 wt % polymer (PCL-PTMC and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) at 72:28 wt %) exhibited a Li-ion conductivity of 1.31 X 10(-4) S/cm and a transference number (t(Li+)) of 0.84 at 60 degrees C, notably higher than those of the pristine PCL-PTMC electrolyte. The prepared composite electrolyte also exhibited an electrochemical stability of up to 5.4 V vs Li+/Li. The interface between the composite electrolyte and a LiFePO4 (LFP) cathode was also improved by direct incorporation of the polymer electrolyte as a binder in the cathode coating. A Li/composite electrolyte/LFP solid-state cell provided a discharge capacity of ca. 140 mAh/g and suitable cycling stability at 55 degrees C after 40 cycles. This study clearly suggests that this type of amorphous polyester-based polymers can be applied in polymer-in-ceramic composite electrolytes for the realization of advanced all-solid-state lithium-ion batteries.
|
|
| 4. |
- Nkosi, Funeka P., et al.
(författare)
-
Understanding Lithium-Ion Conductivity in NASICON-Type Polymer-in-Ceramic Composite Electrolytes
- 2024
-
Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 7:10, s. 4609-4619
-
Tidskriftsartikel (refereegranskat)abstract
- Composite electrolytes comprising distinctive polyether (PEO) or polyester (PCL, P(CL-co-TMC)) polymers in combination with a high loading of Li1.4Al0.4Ti1.6(PO4)3 NASICON-type ceramic powders (LATP, 70 wt %) are investigated to gain insights into the limitations of their ion conductivity in resulting polymer-in-ceramic solid-state electrolyte systems. Here, LATP constitutes an advantageous ceramic Li-ion conductor with fair ionic conductivity that does not immediately suffer from limitations arising from interface issues due to the detrimental formation of surface species (e.g., Li2CO3) in contact with air and/or surrounding polymers. The Li-ion transport in all these composite electrolytes is found to follow a slow-motion regime in the polymer matrix, regardless of the nature of the polymer used. Interestingly, the weakly Li-coordinating polyester-based polymers PCL and P(CL-co-TMC) exhibit an exchange of Li+ ions between the polymer and ceramic phases and high Li-ion transference numbers compared to the polyether PEO matrix, which has strong Li–polymer coordination. LATP particle agglomeration is nevertheless observed in all the composite electrolytes, and this most likely represents a dominating cause for the lower Li-ion conductivity values of these composites when compared to those of their solid polymer electrolyte (SPE) counterparts. These findings add another step toward the development of functional composite electrolytes for all-solid-state batteries.
|
|
| 5. |
- Raju, Kumar, et al.
(författare)
-
Rational Design of 2D Manganese Phosphate Hydrate Nanosheets as Pseudocapacitive Electrodes
- 2020
-
Ingår i: ACS Energy Letters. - : AMER CHEMICAL SOC. - 2380-8195. ; 5:1, s. 23-30
-
Tidskriftsartikel (refereegranskat)abstract
- A new class of 2D nanosheets of nitrogen-integrated phosphate-rich ammonium manganese phosphate hydrate, (NH4MnPO4 center dot H2O) (AMP), has been developed as pseudocapacitive electrode materials. The optimized electrodes exhibited device capacitances of 48.4 and 65.4 F/g for symmetric and asymmetric configurations, respectively. The devices showed excellent energy and power (e.g., 29.4 Wh/kg and 133 kW/kg for asymmetric cells) with extraordinary capacitance retention (e.g., >93%, 100 000 cycles at 5 A/g for asymmetric cells) that surpass those of most of the reported values. The huge pseudocapacitance of AMP is attributed to several factors, including the electroactive sites containing NH4+ ions, the conductive inorganic layers, intercalated water interactions of Mn2+center dot center dot center dot H2O, redox-active phosphate ions, and the 2D nanosheets. AMP-based all-solid-state flexible asymmetric devices exhibited >95% capacitance retention upon 1000 repetitive charge-discharge cycles. This study opens doors to elegant strategies of unlocking the rich physicoelectrochemical properties of 2D AMP for next-generation pseudocapacitors.
|
|
