Na-based batteries are proposed as promising energy storage candidates for beyond Li-ion technology due to the higher natural earth of Na metal. For its high capacity and low potential, Na metal may carve itself a niche when directly used as anodes. Similar to or even more problematic than Li, however, uneven plating/stripping of Na leads to dendrite formation. As the plating substrates, current collectors have a paramount influence on the Na plating/stripping behaviors. Here we propose porous Al current collectors as the plating substrate to suppress Na dendrites. Al does not alloy with Na. It is advantageous over Cu current collectors in terms of cost and weight. The interconnected porous structure can increase available surface for Na to nucleate and decrease the Na flux distribution, leading to homogeneous plating. The Na metal anodes can run for over 1000 cycles on porous Al with a low and stable voltage hysteresis and their average plating/stripping Coulombic efficiency was above 99.9%, which is greatly improved compared to planar Al. We used the porous Al for Na-O, Na-NaV(PO) cells with low Na amount and anode free Na-TiS batteries and anticipate that using this strategy can be combined with further electrolyte and cathodes to develop high performance Na-based batteries.

With its high theoretical capacity and low electrochemical potential, Li metal itself would be the ideal anode for Li-ion batteries. However, practical use of Li anode has been hindered by its tendency for filament or dendritic growth. Here we report a highly effective scaffold based on crumpled paper ball-like graphene particles. We found that these crumpled graphene balls are suitable for constructing highperformance Li metal anodes.

Sodium-ion batteries are similar in concept and function to lithium-ion batteries, but their development and commercialization lag far behind. One obstacle is the lack of a standard reference electrode. Unlike Li foil reference electrodes, sodium is not easily processable or moldable and it deforms easily. Herein we fabricate a processable and moldable composite Na metal anode made from Na and reduced graphene oxide (r-GO). With only 4.5 % percent r-GO, the composite anodes had improved hardness, strength, and stability to corrosion compared to Na metal, and can be engineered to various shapes and sizes. The plating/stripping cycling of the composite anode was significantly extended in both ether and carbonate electrolytes giving less dendrite formation. We used the composite anode in both Na-O and Na-Na V (PO ) full cells.

Bendable energy-storage systems with high energy density are demanded for conformal electronics. Lithium-metal batteries including lithium-sulfur and lithium-oxygen cells have much higher theoretical energy density than lithium-ion batteries. Reckoned as the ideal anode, however, Li has many challenges when directly used, especially its tendency to form dendrite. Under bending conditions, the Li-dendrite growth can be further aggravated due to bending-induced local plastic deformation and Li-filaments pulverization. Here, the Li-metal anodes are made bending tolerant by integrating Li into bendable scaffolds such as reduced graphene oxide (r-GO) films. In the composites, the bending stress is largely dissipated by the scaffolds. The scaffolds have increased available surface for homogeneous Li plating and minimize volume fluctuation of Li electrodes during cycling. Significantly improved cycling performance under bending conditions is achieved. With the bending-tolerant r-GO/Li-metal anode, bendable lithium-sulfur and lithium-oxygen batteries with long cycling stability are realized. A bendable integrated solar cell-battery system charged by light with stable output and a series connected bendable battery pack with higher voltage is also demonstrated. It is anticipated that this bending-tolerant anode can be combined with further electrolytes and cathodes to develop new bendable energy systems.

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The continuous depletion of fossil fuels, the increase of oil prices, and the need to decrease CO 2 emissions have stimulated intensive research on developing alternative renewable and clean energy sources. [1] Among these alternative energy sources, rechargeable Li-ion batteries (LIBs) are one of the promising candidates. To date, the LIBs basically consisting of a positive electrode (cathode), an electrolyte, and a negative electrode (anode) have widespread applications, such as portable electronic devices, pure electric vehicles (PEVs), and hybrid electric vehicles (HEVs). [2] The state-of-the-art electrolytes are usually the lithium salts (LiPF 6 , LiBF 4 , and LiCF 3 SO 3 ) dissolved in organic solvents, i.e., ethylene carbonate, propylene carbonate, polyethylene oxide, and dimethyl carbonate, [3] which exhibit excellent wetting of the electrodes and produce a fast transfer of Li + ions upon charging and discharging. However, they suffer from flammability, poor electrochemical stability, limited temperature range of operation, and low power density. [4] There is an ever-increasing demand for batteries with a higher energy and power density, although current LIBs offer volumetric and gravimetric energy densities up to 770 Wh L −1 and 260 Wh kg −1 , respectively. [5] To improve the energy/power density of LIBs, one way is to adopt high-potential cathode materials such as LiNi 0.5 Mn 1.5 O 4 (LNMO). The high-voltage plateau of LNMO (≈4.7 V vs Li/Li + ) makes its energy density 20-30% higher than the energy density of commercial LiCoO 2 and LiFePO 4 . [6] However, successful commercialization of the LNMO is restricted in high-energy LIBs due to electrolyte decomposition and side reaction of the cathodes and liquid electrolytes when operating at high voltages. [7,8] The other way to improve the energy/power density is to replace the conventional graphite anode with Li metal. The Li metal, with a low anode potential (−3.04 V vs standard hydrogen electrode) and high specific capacity (3862 mAh g −1 for the Li anode versus 372 mAh g −1 for the graphite anode), [9][10][11] has been considered as the "Holy Grail" of battery technologies. When paired with sulfur and oxygen, the theoretical energy density of Li-S (≈2567 Wh kg −1 ) and Li-O 2 (≈3505 Wh kg −1 ) batteries is far higher than the theoretical energy density of conventional LIBs (≈387 Wh kg −1 ). [12][13][14][15] When Li metal approaches the liquid electrolytes, however, unstable Li/electrolyte interface Rechargeable Li-ion batteries (LIBs) are electrochemical storage device widely applied in electric vehicles, mobile electronic devices, etc. However, traditional LIBs containing liquid electrolytes suffer from flammability, poor electrochemical stability, and limited operational temperature range. Replacement of the liquid electrolytes with inorganic solid-state electrolytes (SSEs) would solve this problem. However, several critical issues, such as poor interfacial compatibility, low ionic conductivity at ambient temperatures, etc., need to be surmounted befor...

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