Multilayer Approach for Advanced Hybrid Lithium Battery Jun Ming,* Mengliu Li, Pushpendra Kumar, and Lain-Jong Li* Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia S Supporting Information *
ABSTRACT: Conventional intercalated rechargeable batteries have shown their capacity limit, and the development of an alternative battery system with higher capacity is strongly needed for sustainable electrical vehicles and handheld devices. Herein, we introduce a feasible and scalable multilayer approach to fabricate a promising hybrid lithium battery with superior capacity and multivoltage plateaus. A sulfur-rich electrode (90 wt % S) is covered by a dual layer of graphite/Li4Ti5O12, where the active materials S and Li4Ti5O12 can both take part in redox reactions and thus deliver a high capacity of 572 mAh gcathode−1 (vs the total mass of electrode) or 1866 mAh gs−1 (vs the mass of sulfur) at 0.1C (with the definition of 1C = 1675 mA gs−1). The battery shows unique voltage platforms at 2.35 and 2.1 V, contributed from S, and 1.55 V from Li4Ti5O12. A high rate capability of 566 mAh gcathode−1 at 0.25C and 376 mAh gcathode−1 at 1C with durable cycle ability over 100 cycles can be achieved. Operando Raman and electron microscope analysis confirm that the graphite/Li4Ti5O12 layer slows the dissolution/migration of polysulfides, thereby giving rise to a higher sulfur utilization and a slower capacity decay. This advanced hybrid battery with a multilayer concept for marrying different voltage plateaus from various electrode materials opens a way of providing tunable capacity and multiple voltage platforms for energy device applications. KEYWORDS: hybrid battery, multilayer, sulfur, lithium titanium oxide, operando Raman
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polysulfide (Li2Sx, x = 4−8) intermediates which diffuse into the electrolyte and may deposit on anodes to promote further reactions (i.e., Li2S4 → 2Li2S2 → 4Li2S).14,15 The formation of insoluble and insulating Li2S on anodes, particularly those directly react with lithium anode in self-discharge,14 is the main cause of sulfur loss and internal resistance increase, thereby leading to low sulfur utilization and severe capacity fading. To reduce the loss of active sulfur materials in the cathode, encapsulation of sulfur in porous or hollow structures, such as carbon (e.g., mesoporous carbon,16,17 hollow carbon,18−20 carbon nanotubes,21,22 graphene oxide23−25), metal oxides,26 and polymers,27,28 has been reported. Other versatile strategies have also been developed to hamper the sulfur dissolution, including (1) choosing a stronger binder,29 (2) applying a polymeric30,31 or solid separator,32,33 (3) adding additives34,35 and/or compensating for polysulfide,36,37 (4) using a porous current collector38 and/or inserting an interlayer in the cell configuration,39,40 and (5) depositing a protective layer (e.g.,
he development of a versatile and sustainable rechargeable battery with high capacity has been pursued intensively in the past two decades, particularly with a strong demand from portable electronic devices and electric vehicles.1,2 The cathode capacity of the commonly used lithium metal oxide is normally less than ∼200 mAh g−1 (e.g.,
