Progress in High‐Voltage Cathode Materials for Rechargeable Sodium‐Ion Batteries

Abstract

potential (E° = −2.71 V vs standard hydrogen electrode (SHE) for Na + /Na, 0.3 V higher than that of Li + /Li).[5] Thus, rechargeable batteries based on sodium electrochemistry are considered as promising alternatives for grid-scale EES applications, which put specific requirements on the cost and sustainable resource supply of the battery. The component parts and the working principle for sodium-ion batteries (SIBs) are quite similar to those of LIBs, as shown in Figure 1. [6] Na + ions migrate between a positive electrode (cathode) and a negative electrode (anode) through an Na + electrolyte in between. Both electrodes are composed of intercalation compounds that allow reversible insertion and extraction of Na + ions. [7] Studies on Na + ions intercalation chemistry can be traced back to 1980s, [8] yet they did not attract much attention due to the LIBs, which held significant advantages in energy output and electrochemical stability over other rechargeable batteries and dominated the research/market for the next two decades. With the concern of potential shortage of Li resources, some concerted effort began to revisit the SIB technology and its key materials, especially after the year 2010. Al foil can be used as current collectors for the anode rather than Cu in SIBs because Na does not alloy with Al, which may help to further reduce the cost and increase the energy density. [9] Besides the cost advantages, SIBs also offer opportunities to obtain a faster kinetics with the electrochemical reaction; for example, it may enable a high Na + conductivity in bulk solid within a wide temperature range [10] and an easier charge transfer owing to less pronounced solvation. Such merits, according to the recent work, have led to surprisingly low polarization and high-rate capability (e.g., in Na 3 V 2 (PO 4 ) cathode materials), [11] making SIBs quite appealing for high-power applications. [12] Although SIBs present a less expensive raw materials compared with LIBs, it is worth noting that the higher energynormalized cost of prototype SIBs [13] demonstrates the importance to improve its energy density, which can be realized by increasing the output voltage or capacity. Given that the output voltage of an SIB is determined by the electrode potential difference between the positive and the negative electrodes and the positive electrode is the bottleneck for boosting the energy output of SIBs, major efforts have been devoted to develop advanced cathode materials with high output voltage and high capacity. [14] Prominent potential cathode candidates including Room-temperature rechargeable sodium-ion batteries are considered as a promising alternative technology for grid and other storage applications due to their competitive cost benefit and sustainable resource supply, triumphing other battery systems on the market. To facilitate the practical realization of the sodium-ion technology, the energy density of sodium-ion batteries needs to be boosted to the level of current commercial Li-ion batteries. An effective approach...

Rational Architecture Design Enables Superior Na Storage in Greener NASICON‐Na4MnV(PO4)3 Cathode

“…Herein, to optimize charge carriers' mobility in Na 4 MnV(PO 4 ) 3 , the NASICON-structured material and a highly conductive network are rationally integrated through a feasible solution-route method, fabricating a novel Na 4 MnV(PO 4 ) 3 nanograin with in situ carbon coating that is supported by porous 3D graphene aerogel (GA) material (denoted as NMVP@C@GA). The architecture has the following prominent advantages: (i) the nanoparticles shorten the sodium-ion diffusion length; (ii) the conducting network greatly improves the electronic conductivity of the material; (iii) the robust GA is able to buffer volume changes during Na + insertion/extraction, offering better cycling stability; (iv) the porous structure with large ion-accessible sites greatly increases the contact area of electrolyte/electrode, leading to a full utilization of the active materials.…”

Dopant Segregation Boosting High‐Voltage Cyclability of Layered Cathode for Sodium Ion Batteries

“…Thus, layer structured LiCoO 2 , ternary NMC (LiNi x Mn y Co z O 2 , x + y + z = 1), and NCA (LiNi 0.85 Co 0.1 Al 0.05 O 2 ) have achieved great commercial success as high-performance cathode materials for LIBs. [18][19][20] The surface/interface degradations are attributed to the chemical reactions between cathode and electrolyte, which leads to cathode surface phase transition, [21,22] active material dissolution, [23] passivation layer formation, [24] electrolyte consumption, [25] and so on. [12,16,17] One of the primary efforts on layered cathodes is further unlocking its capacity potential by narrowing the gap between the practical capacity and theoretical capacity.…”

Intercalation Pseudocapacitance Boosting Ultrafast Sodium Storage in Prussian Blue Analogs

“…[1] Witht he introduction of LIBs into fields such as electric vehicles (EVs) and large-scale energy storage systems (ESSs), the rapidly growingd emand for LIBs is causing battery components such as lithium and cobalt to skyrocket in price. [1,4,5] Considering the higher redox potential of Na/Na + and heavier mass of sodium compared with those of lithium,SIBs are considered as promis-ing candidates for application in large-scale ESSs ands mart grids where the energy density becomes less critical. [1,4,5] Considering the higher redox potential of Na/Na + and heavier mass of sodium compared with those of lithium,SIBs are considered as promis-ing candidates for application in large-scale ESSs ands mart grids where the energy density becomes less critical.…”

“…[1,4,5] Considering the higher redox potential of Na/Na + and heavier mass of sodium compared with those of lithium,SIBs are considered as promis-ing candidates for application in large-scale ESSs ands mart grids where the energy density becomes less critical. [3,4] The kineticsa nd rate capability of af ull battery are largely determined by the electrodes and particularly by the cathode. [3,4] The kineticsa nd rate capability of af ull battery are largely determined by the electrodes and particularly by the cathode.…”