A High‐Rate Aqueous Proton Battery Delivering Power Below −78 °C via an Unfrozen Phosphoric Acid

Abstract

The sluggish ion diffusion and electrolyte freezing with volumetric changes limit the low-T performance of rechargeable batteries. Herein, we report a high-rate aqueous proton battery (APB) operated at and below -78 o C via a 62 wt% (9.5 m) H 3 PO 4 electrolyte. The APB is a rocking-chair battery that operates with protons commuting between a Prussian blue cathode and a MoO 3 anode. At -78 o C, the APB full cells exhibit stable cycle life for 450 cycles, high round-trip efficiency of 85%, and appreciable power performance. The APB delivers 30% of its room-temperature capacity even at -88 o C. The proton storage mechanism is investigated by ex situ synchrotron XRD, XAS, and XPS. The APB pouch cells demonstrate nil capacity fading at -78 o C, which offers a safe and reliable candidate for high-latitude applications.

Flexible Free‐Standing MoO3/Ti3C2Tz MXene Composite Films with High Gravimetric and Volumetric Capacities

“…These redox peaks can be attributed to the insertion/extraction of H + in combination with the reduction and oxidation of Mo (Mo 6+ ↔ Mo 5+ ↔ Mo 4+ ). [ 26,27 ] The whole process can be expressed by the following somewhat generalized equations …”

“…Ragone plots for 8:2//NAC hybrid capacitors and previously reported values: a) specific values compared with mass loadings of ≈2 mg cm −2 , such as MnCo 2 O 4 @NiMoO 4 //AC in KOH, [ 30 ] Ti 3 C 2 T z //PEDOT@rGO in H 2 SO 4 , [ 31 ] NiO//rGO in KOH [ 32 ] Co(OH) 2 //N‐doped graphene in KOH, [ 33 ] Ti 3 C 2 T z /Ni‐Co‐Al‐LDH//AC in KOH, [ 34 ] NiCo 2 S 4 /Ti 3 C 2 T z //AC in KOH, [ 35 ] TC‐9//Ti 3 C 2 T z in KOH, [ 36 ] Ni–S/Ti 3 C 2 T z //Ti 3 C 2 T z in KOH, [ 37 ] ML‐80//MG‐5 in KOH, [ 38 ] Ti 3 C 2 T z /CoS 2 (CCH)//rGO in KOH, [ 39 ] CoNi 2 S 4 //AC in KOH, [ 40 ] Ni x Co 3− x O 4 //AC in KOH, [ 41 ] Co 3 O 4 //AC in KOH, [ 42 ] CuO//AC in KOH, [ 43 ] Ni(OH) 2 /CNT/NF//AC in KOH, [ 44 ] Ni 3 S 2 /MWCNT‐NC//AC in KOH, [ 45 ] MoO 3 //PBA hydrogen‐ion battery in H 3 PO 4 ; [ 27 ] b) volumetric values compared with mass loadings of ≈1 mg cm −2 , such as Ti 3 C 2 T z //PANI/Ti 3 C 2 T z in H 2 SO 4 , [ 46 ] EGMX1:3//EGMX1:3 in H 2 SO 4 , [ 18 ] V 2 CT z //V 2 CT z in LiCl, [ 47 ] AQS/G‐1//RuO 2 /G in H 2 SO 4 , [ 48 ] Ti 3 C 2 T z /MWCNT//rGO T in H 2 SO 4 , [ 49 ] MXene/P‐100‐H//rGO in H 2 SO 4 , [ 50 ] Mo 1.33 C/PEDOT:PSS//Mo 1.33 C/PEDOT:PSS in H 2 SO 4 , [ 20 ] N‐doped Ti 3 C 2 T z //N‐doped Ti 3 C 2 T z in H 2 SO 4 , [ 51 ] and MoO 3 /Ti 3 C 2 T z //MoO 3 /Ti 3 C 2 T z in H 2 SO 4 . [ 52 ] …”

Ultrahigh Areal Capacity Hydrogen‐Ion Batteries with MoO3 Loading Over 90 mg cm−2

“…As seen from Figure S17b (Supporting Information), the full cell with high loading electrodes exhibits a specific capacity of 53.7 mAh g −1 and a gravimetric energy density of 34.8 Wh kg −1 at 0.25 C, which is comparable to the state-of-the-art CuFe-TBA// MoO 3 full cell (46 mAh g −1 and 40 Wh kg −1 ; the areal loading of MoO 3 anode and pre-protonated CuFe-TBA cathode was ≈1.5 and ≈2.3 mg cm −2 , respectively). [22] The well-maintained capacity and energy density are mainly attributed to the complete diffusion of hydrogen ions through both thick anode and cathodes. Notably, some reported high areal capacities of electrode materials in LIBs, SIBs, and Li-S were realized by special electrode modifications such as introducing great amounts of carbon nanotubes.…”

“…[ 16 ] Recently, a high‐rate aqueous proton battery operated below −78 °C is developed, which drives the development of batteries for high‐latitude applications. [ 22 ] However, despite all these promising developments, a hydrogen‐ion battery with both high power density and high energy density is yet to be achieved.…”

A Non‐aqueous H3PO4 Electrolyte Enables Stable Cycling of Proton Electrodes

“…This is similar to the capacity obtained from concentrated aq. H 3 PO 4 we recently reported [7c] . However, in aq.…”