Abstract
Doping is a well-known strategy to enhance the electrochemical energy storage performance of layered cathode materials. Many studies on various dopants have been reported; however, a general ...relationship between the dopants and their effect on the stability of the positive electrode upon prolonged cell cycling has yet to be established. Here, we explore the impact of the oxidation states of various dopants (i.e., Mg
2+
, Al
3+
, Ti
4+
, Ta
5+
, and Mo
6+
) on the electrochemical, morphological, and structural properties of a Ni-rich cathode material (i.e., LiNi
0.91
Co
0.09
O
2
). Galvanostatic cycling measurements in pouch-type Li-ion full cells show that cathodes featuring dopants with high oxidation states significantly outperform their undoped counterparts and the dopants with low oxidation states. In particular, Li-ion pouch cells with Ta
5+
- and Mo
6+
-doped LiNi
0.91
Co
0.09
O
2
cathodes retain about 81.5% of their initial specific capacity after 3000 cycles at 200 mA g
−1
. Furthermore, physicochemical measurements and analyses suggest substantial differences in the grain geometries and crystal lattice structures of the various cathode materials, which contribute to their widely different battery performances and correlate with the oxidation states of their dopants.
The steady increase in global sales of electric vehicles (EVs) owes much to high-energy-density lithium-ion batteries, whose energy density and cost are largely dictated by the cathodes. Although ...Ni-rich, layer-structured cathodes have been adequate for application in the existing fleet of EVs, there are compelling reasons to eliminate Co from the current family of layered oxide cathodes. However, the realization of Co-free cathodes poses significant technical challenges. In this perspective, we compare the performances and cost efficiencies of Co-free LiNi
x
Mn
1−
x
O
2
(NM), Co-poor LiNi
x
Co
y
Mn
1−
x
−
y
O
2
(NCM), with
x
> 0.9, and LiFePO
4
(LFP) cathodes, to evaluate their commercial viability for future EVs. We then systematically outline the intrinsic challenges and possible strategies for the development of advanced Co-free/Co-poor layered and LFP cathodes. As battery requirements vary depending on their application, a range of distinct Co-free/Co-poor cathodes will be required to address diverse commercial needs.
This perspective discusses the challenges to, and strategies for, the commercially viable development of these three classes of cathodes for LIBs.
Nickel adds to the capacity of layered oxide cathodes of lithium-ion batteries but comprises their stability. We report a petal-grained LiNi0.89Co0.10Sb0.01O2 cathode that is, nevertheless, stable. ...The stability originates from the ordering of the nanosized grains in a dense, flower-petal-like array, where the elongated and nearly parallel grains radiate from the center to the surface. The ordering of the grains prevents microcrack generation from abrupt lattice changes of the stressful H2–H3 phase transition. The tight packing of the nanograins is conserved upon cycling, preventing destructive seepage of the electrolytic solution into the particles. The half-cell, cycling between 2.7–4.3 V versus Li/Li+ at a 0.5 C rate retains 95.0% of its initial capacity of 220 mAh g–1 after 100 cycles. The full-cell, cycling with a graphite anode and between 3.0–4.2 V at a 1 C rate, retains 83.9% of its initial capacity after 1000 cycles.
This Perspective discusses the prospective strategies for overcoming the stability and capacity trade-off associated with increased Ni content in layered Ni-rich LiNi x Co y Mn z O2 (NCM) and LiNi ...x Co y Al z O2 (NCA) cathodes. The Ni-rich NCM and NCA cathodes have largely replaced the LiCoO2 cathodes in commercial batteries because of their lower cost, higher energy density, good rate capability, and reliability that has been extensively field-tested. Nevertheless, they suffer from microcrack generation along grain boundaries and Ni3+/4+ reactivity that rapidly deteriorate electrochemical performance. Doping and coating have been efficient strategies in delaying the onset of the damage, but they fail to overcome the degradation. There are, however, alternative strategies that directly counter the inherent degradation through micro- and nanostructural modifications of the Ni-rich NCM and NCA cathodes.
Electrochemical water splitting is one of the most promising approaches for sustainable energy conversion and storage toward a future hydrogen society. This demands durable and affordable ...electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). In this study, we report the preparation of uniform Ni-P-O, Ni-S-O, and Ni-S-P-O electrocatalytic films on nickel foam (NF) substrates
via
flow cell-assisted electrodeposition. Remarkably, electrodeposition onto 12 cm
2
substrates was optimized by strategically varying critical parameters. The high quality and reproducibility of the materials is attributed to the use of a 3D-printed flow cell with a tailored design. Then, the as-fabricated electrodes were tested for overall water splitting in the same flow cell under alkaline conditions. The best-performing sample, NiSP/NF, required relatively low overpotentials of 93 mV for the HER and 259 mV for the OER to produce a current density of 10 mA cm
−2
. Importantly, the electrodeposited films underwent oxidation into amorphous nickel (oxy)hydroxides and oxidized S and P species, improving both HER and OER performance. The superior electrocatalytic performance of the Ni-S-P-O films originates from the unique reconstruction process during the HER/OER. Furthermore, the overall water splitting test using the NiSP/NF couple required a low cell voltage of only 1.85 V to deliver a current density of 100 mA cm
−2
. Overall, we demonstrate that high-quality electrocatalysts can be obtained using a simple and reproducible electrodeposition method in a robust 3D-printed flow cell.
A reproducible and efficient electrodeposition method in a 3D-printed flow cell is used to synthesize high-quality Ni-S-P-O films on nickel foam for overall water splitting.
In this work, practical ways of using first-principles and machine learning calculations in rechargeable Li batteries to understand the associated electrochemical Li storage reactions as well as ...support researchers in identifying the suitable electrode and electrolyte materials are described. We summarize in detail the theoretical approaches for different components of lithium-ion batteries (LIBs) in the simplest possible way by categorizing them into two sections: the first section describes the computational approaches for battery investigations, such as structural (DFT and AIMD-based), electronic, thermoelectric, mechanical, adsorption, ion transport, electrochemical properties, and machine learning (ML) over DFT while the second section discusses the use of these computational approaches to investigate the experimental studies on LIBs. This review will be useful to both experimental and theoretical researchers in understanding the electrochemical Li-ion storage mechanism and enable time- and cost-effective fabrication of LIBs with an emphasis on significantly increasing the energy density, lifetime, and safety.
This study provides deep insights into how computational methods complement and enhance experimental investigations.
Among lithium–sulfur (Li–S) battery materials, sulfurized polyacrylonitrile (SPAN) has attracted substantial attention as a cathode material owing to its potential to bypass the problematic ...polysulfide formation and shuttling effect. Carbonate-based electrolytes have been eschewed compared with ether-based electrolytes because of their poor compatibility with Li metal anodes. In this work, we design and study an electrolyte comprising 0.8 M of lithium bis(trifluoromethanesulfonyl)imide, 0.2 M of lithium difluoro(oxalate)borate, and 0.05 M of lithium hexafluorophosphate in ethyl methyl carbonate/fluoroethylene carbonate = 3:1 v/v solution in the Li–S battery coupled with a Li metal anode and SPAN cathode. The well-designed carbonate-based electrolyte effectively stabilizes both electrodes, delivering high Coulombic efficiencies with stable cyclability. Studies using operando optical microscopy and atomic force microscopy demonstrate that dense, uniform Li deposition is promoted to suppress dendrite growth even at a high current density. Operando Raman spectroscopy reveals a reversible Li+ storage behavior in the SPAN structure through the cleavage of disulfide bonds and their redimerization during lithiation and delithiation. As a result, the proposed Li–S battery delivers an overall capacity retention of 73.5% over 1000 cycles, with high Coulombic efficiencies over 99.9%.
The synthesis and electrochemical insertion of lithium into the Wadsley–Roth NaNb13O33 phase is studied. Lithium intercalation to form LixNaNb13O33 reaches a value of up to x~15, between 3.0 and 1.0 ...V vs. Li+/Li at a slow cycling rate, a capacity of 233 mAh g−1. Within this voltage window, two sharp peaks and one broad peak are observed in the differential capacity plots of lithium intercalation suggesting multiple two‐phase regions. High Li‐ion conductivity and rate capability was demonstrated. The lithium diffusion constant is about an order of magnitude greater than TiNb2O7. The average voltage is about 1.6 V and its high‐rate capability makes NaNb13O33 potentially useful as an anode in a fast‐charge Li‐ion battery application.
Abstract
The synthesis and electrochemical insertion of lithium into the Wadsley–Roth NaNb
13
O
33
phase is studied. Lithium intercalation to form Li
x
NaNb
13
O
33
reaches a value of up to x~15, ...between 3.0 and 1.0 V vs. Li
+
/Li at a slow cycling rate, a capacity of 233 mAh g
−1
. Within this voltage window, two sharp peaks and one broad peak are observed in the differential capacity plots of lithium intercalation suggesting multiple two‐phase regions. High Li‐ion conductivity and rate capability was demonstrated. The lithium diffusion constant is about an order of magnitude greater than TiNb
2
O
7
. The average voltage is about 1.6 V and its high‐rate capability makes NaNb
13
O
33
potentially useful as an anode in a fast‐charge Li‐ion battery application.
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