A Li-ion sulfur full cell with ambient resistant Al-Li alloy anode
Graphical abstract
Herein we report Li-metal-free Li-ion sulfur battery assembled with an Al-Li alloy anode, a sulfurized polyacrylonitrile cathode and a carbonate electrolyte. Pairing Al-Li alloy with sulfur (S) could be a promising strategy to achieve high-energy rechargeable batteries with improved safety due to the improved dendrite suppression and ambient resistance of the anode.
Introduction
Rechargeable batteries based on sulfur cathodes have attracted considerable attention because of the extraordinary capacity (1675 mAh/g) and natural abundance of sulfur. The sulfur cathode can pair with a range of metal anodes, including lithium (Li) [1], [2], [3], sodium (Na) [4], [5], magnesium (Mg) [6], [7] and aluminium (Al) [8], [9]. Among many, Li-S battery is more advantageous on account of the high theoretical capacity of Li metal (3860 mAh/g), high cell voltage (average 2.15 V), and extraordinary energy density of 2500 Wh/kg. As a result, Li-S batteries have triggered remarkable attention since the report by Nazar et al. [3]. In spite of such merits of Li-S cells, however, a number of great challenges including the dendrite and the ambient instability of Li metal, as well as polysulfides shuttling need to be addressed [10]. The dissolution of polysulfides have been studied extensively [11], [12], while the anode part is still uncertain.
The Li dendrite initiated by the inhomogeneous Li deposition could trigger short circuit of the cell, and cause explosion issues. On the other side, the solid electrolyte interphase (SEI) at lithium surface could break off due to the repetitive Li stripping/plating, resulting in the consumption of electrolyte, as well as the low coulombic efficiency. A range of optimized approaches are underway to tackle with this problem. For instance, constructing protective layers containing poly(vinylidene-co-hexafluoropropylene) (PVDF-HFP) and LiF composites on Li metal was proposed [13], [14]. These kinds of protective layers could effectively suppress the random Li deposition and avoid the consumption of excess electrolyte. Electrolyte additives, like LiF-rich layer [15], were also studied to stabilize the SEI on Li metal and alleviate the uncontrolled Li deposition. Surface coating on the electrode materials could suppress the structure change during charge/discharge, and further stabilize the cell performance [16]. Other approaches like electrolyte modification, interfacial engineering, and solid-state electrolyte incorporation could also be found to improve the safety and performance of Li anode [17]. However, the sensitivity of Li metal to air and moisture is still a severe challenge that has not been fully solved.
Meanwhile, Li-based alloy anode represents possible approaches to minimizing the lithium dendrite problem [18], [19]. Among them, aluminium (Al) has shown a great potential because of its high capacity (2980 mAh/g and 8046 mAh/cm3), abundance in earth's crust (8.32%), safety and low market price (~ $0.5–1.5 USD/lb) [20]. The merit of Al alloy lies in the moderate potential versus Li°/Li+. The measured potential of Al alloy vs Li°/Li+ is around 0.2–0.3 V, and it could disadvantage the lithium dendrite growth that occurs with silicon or graphite anodes (<0.05 V vs Li°/Li+), which is crucial for battery safety. It is worth noting that the electrode expansion/shrinkage upon alloying/de-alloying could potentially be a challenge for the alloy anode [21], [22], [23]. Even though, Al has much smaller volume change (~ 96%), compared with other alloy anodes, such as Si alloy (320%), Sn alloy (260%) and Sb alloy (200%) [24]. Another advantage for Al alloy is the existence of surface Al2O3, which could likely provide a stable oxide cover to isolate the alloy from air or moisture, and slow down the rigorous oxidation. It is expected that Al-Li alloy might be a safe replacement anode for lithium metal in the Li-metal-free sulfur battery in order to simultaneously address both the dendrite and air instability issues of lithium metal.
In this work, we report a rechargeable 1.5 V Li-ion sulfur battery with Al-Li alloy anode and sulfurized polyacrylonitrile (SPAN) cathode, where Li ions as charge carrier to shuttle between both electrodes. SPAN was confirmed to undergo solid-state reaction in the carbonate electrolyte without any shuttle phenomenon, which would happen in ether electrolyte [25]. Al-Li alloy as anode material could operate as alternative anodes to minimizing the lithium dendrite problem, along with the merits of mitigating oxidation of Al-Li surface in air. In the meanwhile, the low potential (0.28 V, vs. Li°/Li+) of the alloying reaction of Al anode with Li ions (Li+) enables a relatively high cell voltage of 1.5 V, in contrast to Al-S cell (<1 V). It is further demonstrated that the cell performance is largely improved by applying pre-lithiation to either the Al anode or the sulfur cathode. The optimised cells have initial cathode capacity of 550 mAh/g at 200 mA/g and endure 200 cycles with a decaying rate of 0.09% per cycle. The specific energy based on the total weight of active materials in the full cell ranges from 589 Wh/kg to 762 Wh/kg, which is a function of the specific electrode compositions.
Section snippets
Preparation of sulfurized polyacrylonitrile (SPAN) particles
SPAN was fabricated by heating a mixture of polyacrylonitrile and sulfur with a mass ratio of 1:3 in a tube furnace under the nitrogen atmosphere at 500 °C.
Preparation of SPAN cathodes
Then as-prepared SPAN material was mixed with binder (Alginate, Sigma Aldrich) and carbon black at a ratio of 70 wt%: 15 wt%: 15 wt%. The mixture was grounded in water to get homogenous slurry. The slurry casted onto the carbon-coated aluminium foil and dried in a vacuum oven under 80 °C for 24 h. The slurry-loaded foil was punched into
Results and discussion
The alloy/de-alloy process of Al-Li half-cell was measured using galvanostatic charge/discharge method. As shown in Fig. 1(a), the alloy reaction between Al and Li was around 0.28 V while the de-alloy process occurred at 0.42 V vs. Li/Li+. The Al-Li alloy could consist of three different structures, including AlLi, Al2Li3 and Al4Li9. The composition of the Al-Li alloy was dependent on the charging time (alloy formation) as displayed by the ex situ XRD in Fig. S1. With the reaction time
Acknowledgements
We acknowledge the support from Faculty of Engineering, The University of New South Wales, and the Australian Research Council (DP160103244). The authors acknowledge the facilities and the scientific and technical assistance from Mark Wainwright Analytical Centre, The University of New South Wales.
References (39)
- et al.
Research on sodium sulfur battery for energy storage
Solid State Ion.
(2008) - et al.
A novel non-aqueous aluminum sulfur battery
J. Power Sources
(2015) - et al.
Multi-functional separator/interlayer system for high-stable lithium-sulfur batteries: progress and prospects
Energy Storage Mater.
(2015) - et al.
Pre-modified Li3PS4 based interphase for lithium anode towards high-performance Li-S battery
Energy Storage Mater.
(2018) - et al.
Enabling reliable lithium metal batteries by a bifunctional anionic electrolyte additive
Energy Storage Mater.
(2018) - et al.
Engineering of lithium-metal anodes towards a safe and stable battery
Energy Storage Mater.
(2018) - et al.
Li-ion battery materials: present and future
Mater. Today
(2015) - et al.
Lithium reactions with intermetallic-compound electrodes
J. Power Sources
(2002) - et al.
Nano- and bulk-silicon-based insertion anodes for lithium-ion secondary cells
J. Power Sources
(2007) A review of the electrochemical performance of alloy anodes for lithium-ion batteries
J. Power Sources
(2011)
Charge/discharge characteristics of sulfurized polyacrylonitrile composite with different sulfur content in carbonate based electrolyte for lithium batteries
Electrochim. Acta
Implantable solid electrolyte interphase in lithium-metal batteries
Chemistry
Stabilizing Li/electrolyte interface with a transplantable protective layer based on nanoscale LiF domains
Nano Energy
Rechargeable lithium – sulfur batteries
Chem. Rev.
Nanostructured sulfur cathodes
Chem. Soc. Rev.
A highly ordered nanostructured carbon–sulphur cathode for lithium–sulphur batteries
Nat. Mater.
Development of sodium-sulfur batteries
Int. J. Appl. Ceram. Technol.
Progress in rechargeable magnesium battery technology
Adv. Mater.
Performance improvement of magnesium sulfur batteries with modified non-nucleophilic electrolytes
Adv. Energy Mater.
Cited by (45)
New insights into Li-argyrodite solid-state electrolytes based on doping strategies
2024, Coordination Chemistry ReviewsHighly reversible lithium metal batteries enabled by spontaneous alloying anode
2024, Journal of Physics and Chemistry of SolidsA lithium metal foil counter/reference electrode with surface enriched by Li<inf>1+x</inf>Al alloy
2023, Journal of Power SourcesPursuing high voltage and long lifespan for low-cost Al-based rechargeable batteries: Dual-ion design and prospects
2023, Energy Storage MaterialsMXene-based composites for high-performance and fire-safe lithium-ion battery
2023, Current Applied PhysicsUltrathin Li-rich Li-Cu alloy anode capped with lithiophilic LiC<inf>6</inf> headspace enabling stable cyclic performance
2023, Journal of Colloid and Interface Science