Advances on Na-K liquid alloy-based batteries

Sodium-potassium(Na^(-)K)liquid alloys attract increasing research attention,as an ideal alternative of Li metal for metal-based batteries,attributing to their high abundance,low redox potential,high capacity,and dendrite-free properties.In addition,the liquid and self-healing features of Na^(-)K alloys endow good electrode/electrolyte interfacial contact.The recent advances on the Na^(-)K liquid alloy-based batteries(NKBs)are reviewed herein.The anode designs for immobilization of the liquid alloy are introduced.The influences of the electrolyte and cathode materials on the battery performances are discussed.In addition,considering the co-existence of both K^(+)and Na^(+)in the electrolyte,the working mechanisms of the NKBs are elaborated.We also show that despite the improvement,challenges of the NKBs remain.The compatibility between Na^(-)K liquid alloy and electrolyte,as well as disputed working mechanisms,request detailed surface analyses of the liquid alloy and local element distribution evolution in the battery.This review would shed light on the fundamental understanding of Na^(-)K alloy electrochemistry and the development of dendrite-free metal-based energy storage systems with high energy density.

Recent advances in modification strategies of silicon-based lithiumion batteries

As potential alternatives to graphite,silicon(Si)and silicon oxides(SiO_(x))received a lot of attention as anode materials for lithiumion batteries owing to their relatively low working potentials,high theoretical specific capacities,and abundant resources.However,the commercialization of Si-based anodes is greatly hindered by their massive volume expansion,low conductivity,unstable solid electrolyte interface(SEI),and low initial Coulombic efficiency(ICE).Continuous endeavors have been devoted to overcoming these challenges to achieve practical usage.This review is centered on the major challenges and latest developments in the modification strategies of Si-based anodes,including structure optimization,surface/interface regulation,novel binders,and innovative design of electrolyte.Finally,outlooks and perspectives of Si-based anodes for future development are presented.

Challenges and progresses of energy storage technology and its application in power systems

As a flexible power source,energy storage has many potential applications in renewable energy generation grid integration,power transmission and distribution,distributed generation,micro grid and ancillary services such as frequency regulation,etc.In this paper,the latest energy storage technology profile is analyzed and summarized,in terms of technology maturity,efficiency,scale,lifespan,cost and applications,taking into consideration their impact on the whole power system,including generation,transmission,distribution and utilization.The application scenarios of energy storage technologies are reviewed and investigated,and global and Chinese potential markets for energy storage applications are described.The challenges of large-scale energy storage application in power systems are presented from the aspect of technical and economic considerations.Meanwhile the development prospect of global energy storage market is forecasted,and application prospect of energy storage is analyzed.

Efficient oxygen electrocatalysts with highly-exposed Co-N4 active sites on N-doped graphene-like hierarchically porous carbon nanosheets enhancing the performance of rechargeable Zn-air batteries

Designing bifunctional oxygen electrocatalysts with high activity,lasting stability,and low-cost for rechargeable zinc-air batteries(RZABs)is a tough challenge.Herein,an advanced electrocatalyst is prepared by anchoring atomically dispersed Co atoms on Ndoped graphene-like hierarchically porous carbon nanosheets(SA-Co-N4-GCs)and thereby forming Co-N4-C architecture.Its unique structure with excellent conductivity,large surface area,and three dimensional(3D)interconnected hierarchically porous architecture exposes not only more Co-N4 active sites to accelerate the kinetics of both oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),but also provides an efficient charge/mass transport environment to reduce diffusion barrier.Consequently,SA-Co-N4-GCs exhibits excellent ORR/OER bifunctional activities and durability,surpassing noble-metal catalysts.Liquid RZABs using SA-Co-N4-GCs cathodes display a high open-circuit voltage of 1.51 V,a remarkable power density of 149.3 mW·cm−2,as well as excellent stability and rechargeability with faint increase in polarization even at a large depth of charge–discharge cycle with 16 h per cycle over an entire 600 h long-term test.Moreover,flexible quasi-solid-state RZABs with SA-Co-N4-GCs cathodes also deliver a considerable power density of 124.5 mW·cm−2,which is even higher than that of liquid batteries using noble-metal catalysts.This work has thrown new insight into development of high-performance and low-cost electrocatalysts for energy conversion and storage.