electrochemical reactions in SCs, which can take advantage of the anions in electrolyte to achieve the energy storage. [3] However, SCs store ions only at the interfaces between electrodes and electrolyte, making their energy densities too low to power the high-energy devices ( Figure S1, Supporting Information). Although the recently proposed aluminium ion battery exhibits excellent cycling performance, [4] the relatively low energy density still needs to be addressed due to the low working voltage. Hence, it is highly urgent to develop the de-/intercalation reaction based dual-ion battery (DIB) with theoretically high energy density. [5] The first DIB with dual-graphite configuration was presented in 1989, in which graphite was used as both cathode and anode, realizing anion de-/intercalation in the cathodic graphite electrode. [6] In addition, the term of "dual-ion battery" was proposed for the first time by Winter and co-workers in 2012. [7] Different from the traditional Li/Na-ion batteries in which cationic charge carriers are initially originated from cathode materials, the electrolyte provides all charge carriers including anions and cations in the DIB. This means that the capacity delivered by DIB would not be limited by the usually low Coulombic efficiency (CE) of electrodes due to the sufficient supply of ions from electrolyte. [5b] However, the redox reactions of anion de-/intercalation on graphite cathode are usually taken place at a high potential, nearly or higher than 5.0 V versus Li + / Li, which exceeds the anodic stabile window of conventional carbonate electrolytes. As a result, such anion de-/intercalation processes usually suffer from severe side reactions, such as decomposition of electrolyte, [8] exfoliation of graphene layers, [9] and some unknown irreversible electrochemical reactions, leading to the very low CE (usually lower than 90%) during early cycling and hence poor cyclic stability. [10] In order to conquer these issues to improve the energystorage performance of DIB, there are four strategies proposed recently: 1) the utilization of ionic liquids with wider electrochemical stable window as the high-voltage electrolyte, which is hard to realize practicality due to the much expensive price; [11] 2) applying alloying metals (such as Al and Sn) with the higher redox potential to replace the metallic Li anode, greatly improving the cycle life of DIB to over 1500 cycles as Conventional ion batteries utilizing metallic ions as the single charge carriers are limited by the insufficient abundance of metal resources. Although supercapacitors apply both cations and anions to store energy through absorption and/or Faradic reactions occurring at the interfaces of the electrode/electrolyte, the inherent low energy density hinders its application. The graphite-cathodebased dual-ion battery possesses a higher energy density due to its high working potential of nearly 5 V. However, such a battery configuration suffers from severe electrolyte decomposition and exfoliation of the graphite cath...

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/aenm.201703252. Low-Temperature BatteriesIn order to substitute the currently market-dominant lithiumion batteries (LIBs), which would become unaffordable to consumers due to the low abundance and uneven distribution of Li resources in the Earth's crust and therefore the higher and higher prices, sodium-based batteries (SBBs) have drawn great attentions of energy-storage scientists. [1][2][3][4][5] Traditionally, SBBs are the molten-sodium batteries, mainly including the high temperature (high-T) sodium-sulfur and sodium-metal halide (ZEBRA) batteries, which are built with a solid electrolyte of

The exhausted graphite from spent Li-ion batteries is recycled and reused as a favorable anode for Na/K-ion batteries, and the insights into structural de-/intercalation model are realized.

Hard carbon is regarded as a promising anode material for sodium‐ion batteries (SIBs). However, it usually suffers from the issues of low initial Coulombic efficiency (ICE) and poor rate performance, severely hindering its practical application. Herein, a flexible, self‐supporting, and scalable hard carbon paper (HCP) derived from scalable and renewable tissue is rationally designed and prepared as practical additive‐free anode for room/low‐temperature SIBs with high ICE. In ether electrolyte, such HCP achieves an ICE of up to 91.2% with superior high‐rate capability, ultralong cycle life (e.g., 93% capacity retention over 1000 cycles at 200 mA g−1) and outstanding low‐temperature performance. Working mechanism analyses reveal that the plateau region is the rate‐determining step for HCP with a lower electrochemical reaction kinetics, which can be significantly improved in ether electrolyte.