Potassium ion capacitors (PICs) have the potential to combine the advantages of capacitors and batteries, making them promising energy storage substitutes for existing systems. Biomass‐based‐electrodes are very promising materials for potassium storage, however, at present, the acquisition of biomass‐based‐electrodes is mainly dependent on high temperature calcination, which makes the efficient utilization of biomass materials quite challenging. Herein, in accordance with ex‐situ 13C NMR and Raman, a universally directional selection strategy of biomass precursors through an advanced pre‐diagnosis method for calcination intermediates and a sulfur engineering strategy are initially proposed, proving that the carbon materials derived from precursors with fewer aliphatic chains and more aromatic carbons show a higher yield and can be have more K ions inserted. In addition, the evolution mechanism of in‐plane/interlayered CS bonds is thoroughly evaluated. Notably, PICs assembled by such carbon materials as the battery‐type anode, deliver a high energy density of 151 Wh kg‐1 and an ultrahigh power output of 10 kW kg‐1, closing to state‐of‐the‐art values for PICs. This breakthrough opens up a new avenue for targeted design of biomass materials and offers in‐depth insights into the evolution of S‐C bonds, promoting the energy/power density of PICs devices to a higher level.

Spinel LiMn2O4 is a promising cathode material for lithium-ion batteries ascribed to its steady bulk structure and abundant manganese sources. Nevertheless, grievous capacity decay due to the Jahn-Teller effect and...

Highlights Interfacial bonding strategy has been successfully applied to address the high overpotential issue of sacrificial additives, which reduced the decompositon potential of Na2C2O4 from 4.50 to 3.95 V. Ultra-low-dose technique assisted commercial sodium ion capacitor (AC//HC) could deliver a remarkable energy density of 118.2 Wh kg−1 as well as excellent cycle stability. In-depth decomposition mechanism of sacrificial compound and the relative influence after pre-metallation were revealed by advanced in situ and ex situ characterization approaches. Abstract Sacrificial pre-metallation strategy could compensate for the irreversible consumption of metal ions and reduce the potential of anode, thereby elevating the cycle performance as well as open-circuit voltage for full metal ion capacitors (MICs). However, suffered from massive-dosage abuse, exorbitant decomposition potential, and side effects of decomposition residue, the wide application of sacrificial approach was restricted. Herein, assisted with density functional theory calculations, strongly coupled interface (M–O–C, M = Li/Na/K) and electron donating group have been put forward to regulate the band gap and highest occupied molecular orbital level of metal oxalate (M2C2O4), reducing polarization phenomenon and Gibbs free energy required for decomposition, which eventually decrease the practical decomposition potential from 4.50 to 3.95 V. Remarkably, full sodium ion capacitors constituted of commercial materials (activated carbon//hard carbon) could deliver a prominent energy density of 118.2 Wh kg−1 as well as excellent cycle stability under an ultra-low dosage pre-sodiation reagent of 15–30 wt% (far less than currently 100 wt%). Noteworthily, decomposition mechanism of sacrificial compound and the relative influence on the system of MICs after pre-metallation were initially revealed by in situ differential electrochemical mass spectrometry, offering in-depth insights for comprehending the function of cathode additives. In addition, this breakthrough has been successfully utilized in high performance lithium/potassium ion capacitors with Li2C2O4/K2C2O4 as pre-metallation reagent, which will convincingly promote the commercialization of MICs.

The implementation of Ni-rich cathodes with high energy density has been critically restrained by stress corrosion. Herein, crackfree LiNbO 3 -coated LiNi 0.88 Co 0.10 Mn 0.02 O 2 , as theoretically predicted, demonstrates highly reversible lithiation/delithiation. Mechanically, the phase transition (H1 → H2 → H3) is significantly alleviated by the excogitation of the interfacial force invoked by the LiNbO 3 coating layer, as verified by X-ray absorption spectroscopy and extended X-ray absorption near-edge structure spectroscopy. Meanwhile, the stabilities of the crystal structure are remarkably strengthened by the strong Nb−O bond activated by Nb 5+ doping that is confirmed by Rietveld refinement of X-ray diffraction and differential capacitance curves. Chemically, the interface shielding effect is conducive to protecting the electrode against electrolyte corrosion along with subsequent transition-metal dissolution, ultimately rendering a faster/highly convertible lithium-ion diffusion. Greatly, the excellent electrochemical properties (74% capacity retention after 300 cycles at 2 C within 2.5−4.3 V) and structural stability (the morphology remains intact after 500 cycles at 5 C within 2.5−4.3 V) are successfully achieved. Given this, this elaborate work might inaugurate a potential avenue for rationally tuning the structure/interface evolution toward Ni-rich materials.

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