How Oxygen Inside Your Phone's Battery Is Secretly Holding Your Daily Charge

In late June 2026, a pair of highly technical studies quietly dismantled one of the most stubborn dogmas in materials science, revealing a hidden, atomic-scale drama unfolding inside billions of consumer electronic devices.

First, on June 21, 2026, a research team led by Prof. Wang Chunyang at the Institute of Metal Research, Chinese Academy of Sciences (CAS), mapped out the exact atomistic chain of failure that destroys lithium cobalt oxide ($LiCoO_2$) cathodes under high-voltage charging. Just over a week later, on June 29, 2026, researchers from the University of Dundee and the University of Warwick published a study in Nature Nanotechnology demonstrating that oxygen within a battery's positive electrode is not just a passive structural frame, but an active, energetic partner in storing and releasing electrical charge.

Together, these findings resolve a mystery that has puzzled electrochemists for decades: why even the most sophisticated lithium-ion batteries inevitably lose their capacity, leaving smartphones struggling to hold a charge after a year or two of daily use.

The answer lies in the oxygen trapped inside the chemical lattice of the battery's cathode. Under the intense electrical stress of modern fast charging, this oxygen undergoes a split-second transition, acting as both an unexpected savior of energy density and a silent saboteur of structural stability.

By analyzing these twin breakthroughs as a unified case study, we can extract profound lessons about the limits of current consumer technology, the physical boundaries of energy storage, and the upcoming engineering principles that will define the next generation of smartphones, laptops, and electric vehicles.

The Conventional Model: Where the Science Was Incomplete

To understand why this dual discovery is so disruptive, it is necessary to examine the fundamental mechanics of how phone batteries work.

For the past thirty years, the standard textbook explanation of lithium-ion chemistry focused almost entirely on the movement of metal ions. A standard smartphone battery is an electrochemical sandwich comprised of three primary players:

The Anode (Negative Electrode): Usually made of graphite, which acts as a carbon-based honeycomb to store lithium ions when the battery is fully charged.
The Cathode (Positive Electrode): Typically made of a layered transition metal oxide, such as Lithium Cobalt Oxide ($LiCoO_2$) or Nickel-Manganese-Cobalt ($NMC$).
The Electrolyte: A liquid or gel solvent containing lithium salts that allows ions to shuttle back and forth between the electrodes.

       CHARGING: Ions move to Anode (Graphite)
   [Anode: Graphite] <=== (Li+ Ions) === [Cathode: LiCoO2]
   [Anode: Graphite] === (Li+ Ions) ===> [Cathode: LiCoO2]
     DISCHARGING: Ions return to Cathode (Metal Oxide)

In this conventional model, the transition metal atoms—cobalt, nickel, manganese, or iron—are considered the heavy lifters of the cathode. When you plug your phone into a wall charger, an external electrical current forces lithium ions out of the cathode's crystalline lattice, through the liquid electrolyte, and into the graphite anode.

To maintain charge neutrality during this process, the transition metals in the cathode must oxidize, surrendering electrons to the external circuit. When you unplug your phone and use it, the process reverses: lithium ions migrate back to the cathode, and the metal atoms reduce, accepting electrons and powering your device's screen, processor, and cellular modems.

Within this classic framework, the oxygen atoms inside the cathode were long assumed to be chemically inert. They were treated as a passive, ionic scaffold—a highly stable negative matrix ($O^{2-}$) whose only job was to hold the positively charged transition metals and lithium ions in a structured, layered grid.

However, this structural model suffered from a major mathematical discrepancy. When materials scientists calculated the theoretical limit of how much energy these metal ions could exchange, the numbers did not align with real-world observations. Cathodes made with specific, lithium-rich structures often exhibited capacities that far exceeded what the transition metals alone could legally support through standard oxidation and reduction.

The missing variable in the equation, as the Dundee and Warwick teams confirmed, was the oxygen itself. It was not just standing by as a structural bystander; it was actively participating in the redox reactions, storing and releasing electrons in a process known as anionic redox.

This revelation fundamentally reshapes our understanding of how phone batteries work. Yet, this energetic participation comes at a massive physical cost—one that directly explains the gradual, frustrating decay of your smartphone's daily battery life.

The Dual Nature of Oxygen: Active Carrier vs. Structural Saboteur

The June 2026 paper published in Nature Nanotechnology utilized sophisticated quantum mechanical simulations and high-resolution laboratory spectroscopy to prove that oxygen actively participates in electron transfer. Led by theoretical physicist Dr. Hrishit Banerjee from the University of Dundee, the team compared two dominant cathode chemistries: phosphate-based cathodes (such as Lithium Iron Phosphate, or $LiFePO_4$) and layered oxide cathodes (such as $LiCoO_2$ and $NMC$).

Their findings revealed a stark chemical contrast:

Phosphate Cathodes ($LiFePO_4$): Because phosphorus forms exceptionally strong, covalent tetrahedral units with oxygen ($PO_4^{3-}$), the oxygen electrons are tightly bound. They remain localized, showing virtually zero involvement in electron exchange during cycling. As a result, $LFP$ batteries are structurally resilient, surviving thousands of cycles, but they possess a lower overall energy density.
Layered Oxide Cathodes ($LiCoO_2$ / $NMC$): In these structures, the metal-oxygen bonds are weaker and more dynamic. When a phone is charged to higher voltages, the transition metals are stripped of their outer electrons. Once these metals reach their maximum oxidation states, the system begins pulling electrons directly from the oxygen anions. The oxygen ($O^{2-}$) oxidizes, temporarily transferring charge and contributing significantly to the battery's overall voltage and storage capacity.

  ENERGY DENSITY VS. LONGEVITY TRADE-OFF:
  
  [LFP Chemistry (Phosphate-based)]
  - Strong covalent PO4 bonds
  - Passive oxygen (no electron sharing)
  - Result: Extremely high cycle life, lower energy density
  
  [LCO/NMC Chemistry (Layered Oxide)]
  - Dynamic metal-oxygen bonds
  - Active oxygen (shares electrons / redox)
  - Result: High energy density (compact phone size), faster degradation

This active "oxygen chemistry" is what allows modern phone manufacturers to squeeze massive amounts of energy into incredibly thin chassis. Without oxygen redox, a typical modern smartphone would require a battery pack nearly double its current thickness to achieve the same daily runtime.

The Dark Side of Oxygen Activity: Lattice Oxygen Loss

While active oxygen redox provides the energy boost that keeps your phone running through a long day of heavy use, it is chemically volatile. When oxygen atoms are stripped of their electrons during high-voltage charging, they transition from stable $O^{2-}$ ions toward neutral, molecular-like oxygen species ($O_2^{2-}$ or even singlet oxygen, $O_2$).

At this point, the oxygen is no longer content to sit quietly in its lattice seat. Under high voltage, these unstable oxygen species begin to migrate through the solid crystal.

This is where Prof. Wang Chunyang's June 2021 and 2026 investigations join the narrative. Operating at the atomic scale using advanced aberration-corrected scanning transmission electron microscopy (STEM), the CAS researchers mapped what happens to Lithium Cobalt Oxide ($LiCoO_2$) when forced to operate under ultra-high-voltage conditions (approaching 5.0 V).

At these extreme voltages—which manufacturers utilize to speed up charging times and maximize power output—the delithiation (removal of lithium) is incredibly deep. With the vast majority of lithium ions extracted, the cobalt-oxygen layers lose their electrostatic glue.

The oxygen atoms at the surface of the cathode nanoparticles are the first to escape, outgassing into the electrolyte. But the damage does not stop at the surface.

As oxygen leaves, it leaves behind atomic-scale vacancies—essentially, physical "holes" in the structural foundation of the cathode.

The Mechanics of Battery Decay: A Step-by-Step Anatomy of Structural Collapse

To understand how these microscopic oxygen vacancies translate to your phone dying at 15% charge or degrading to 79% maximum capacity after 18 months, we must examine the physical cascade of failure identified by both SLAC/Stanford experiments and the 2026 CAS research.

The degradation follows a highly predictable, self-reinforcing chain reaction.

+-------------------------------------------------------------+
|              ULTRA-HIGH VOLTAGE CHARGING (>= 4.5V)          |
+-------------------------------------------------------------+
                               |
                               v
+-------------------------------------------------------------+
|   Deep Delithiation (Nearly all Li+ ions pulled out)        |
+-------------------------------------------------------------+
                               |
                               v
+-------------------------------------------------------------+
|   Oxygen Redox Activated (Oxygen atoms lose electrons)      |
+-------------------------------------------------------------+
                               |
                               v
+-------------------------------------------------------------+
|   Oxygen Outgassing & Vacancy Formation (Holes in lattice)  |
+-------------------------------------------------------------+
                               |
                               v
+-------------------------------------------------------------+
|   Transition Metal Migration (Cobalt/Nickel atoms "dance")  |
+-------------------------------------------------------------+
                               |
                               v
+-------------------------------------------------------------+
|   Lattice Phase Collapse (R3m Layered -> Fm3m Rock-Salt)    |
+-------------------------------------------------------------+
                               |
                               v
+-------------------------------------------------------------+
|   Impedance Rise & Capacity Decay (Phone battery degrades)  |
+-------------------------------------------------------------+

Step 1: Oxygen Outgassing and Vacancy Migration

As established by Stanford Ph.D. researcher Peter Csernica and Associate Professor Will Chueh, oxygen does not leak out of a battery all at once. Instead, it is a slow, insidious "trickle." Over 500 complete charge-discharge cycles, a typical layered oxide cathode loses approximately 6% of its total oxygen content.

This sounds like a minor loss, but on a per-cycle basis, it amounts to roughly $0.012\%$ of the oxygen escaping each time you plug in your phone.

Crucially, the Stanford-SLAC team proved that this oxygen loss is not restricted to the outer surface of the cathode nanoparticles. Once oxygen vacancies form on the surface, they act as conduits. Oxygen atoms deep within the interior of the cathode particle begin to slowly diffuse outward, migrating toward the surface to fill the empty spots, only to be oxidized and lost in turn. This leaves behind a hollowed-out, vacancy-ridden atomic lattice throughout the entire nanoparticle.

Step 2: The Atomic "Dance" of Transition Metals

The physical presence of oxygen atoms is what keeps the transition metal atoms (such as cobalt or nickel) locked into their precise, layered rows. When an oxygen atom leaves, the local electrostatic balance of the crystal is completely disrupted.

Without the oxygen scaffold holding them back, the neighboring transition metal ions undergo what Will Chueh described as a "dance out of their ideal positions."

Deprived of their oxygen anchors, these metal ions slip from their dedicated metal layers and migrate across into the empty spaces that were originally reserved for the lithium ions.

Step 3: Phase Transformation (From Layered to Rock-Salt)

As the cobalt or nickel atoms invade the lithium pathways, they physically block the channels. The pristine, highly structured layered oxide crystal (known crystallographically as the $R\bar{3}m$ rhombohedral structure) begins to warp.

Under the strain of these displaced metal atoms, the local crystal collapses. It transitions first into a disordered "spinel" phase ($Fd\bar{3}m$), and eventually into an electrochemically inactive, highly dense "rock-salt" phase ($Fm\bar{3}m$).

This rock-salt phase is a structural dead end. It is incredibly dense, possesses no open pathways for lithium ions to pass through, and is completely incapable of participating in further redox chemistry.

  CRYSTAL PHASES OF DEGRADATION:
  
  [R-3m Layered Phase] (Pristine, Open Channels)
  Li  Li  Li  Li  Li    <-- Wide open highways for Lithium ions
  O   Co  O   Co  O     <-- Orderly transition metal and oxygen layers
  
  [Fd-3m Spinel Phase] (Partially Blocked)
  Li  Co  Li  Co  Li    <-- Cobalt atoms begin invading Lithium channels
  O   Co  O   Co  O     
  
  [Fm-3m Rock-Salt Phase] (Fully Blocked, Inactive)
  Co  O   Co  O   Co    <-- Lithium pathways totally collapsed
  O   Co  O   Co  O     <-- Battery experiences extreme voltage fade

Step 4: The "Sandwich-Like" Degradation Architecture

Prof. Wang Chunyang’s 2026 CAS study added a vital new piece to this puzzle. Using extreme 5.0 V charging as a stress test, his team discovered that the structural collapse does not occur uniformly.

Instead, the coupling of lattice oxygen loss and global lattice deformation results in a highly strained, multilayered "sandwich-like" degradation architecture on the cathode's surface. This sandwich layer consists of alternating bands of highly deformed layered structures, disordered spinel structures, and dead rock-salt zones.

This degraded shell acts as a high-resistance barrier. It severely hinders $Li^+$ reinsertion during discharging, meaning that even if the interior of your battery's cathode is still healthy and full of lithium, the ions cannot physically pass through the damaged outer "sandwich" to get back in.

This forces your phone's processor to work with a lower operating voltage, leading to "voltage fade" and causing the operating system to report a premature drop in battery percentage.

Cathode State	Crystallographic Phase	Lithium Ion Mobility	Oxygen Content Loss	Contribution to Voltage Fade
Pristine (0-50 Cycles)	$R\bar{3}m$ Rhombohedral (Layered)	Extremely High (Open highways)	0%	None
Moderate (100-300 Cycles)	Mixed $R\bar{3}m$ & $Fd\bar{3}m$ (Spinel)	Moderate (Partial blockage)	1.5% - 3.0%	Minor (3-5% capacity loss)
Highly Degraded (500+ Cycles)	Multilayered "Sandwich" ($Fm\bar{3}m$ Rock-Salt)	Extremely Low (Blocked pathways)	6.0%+	Severe (10-15% voltage/capacity drop)

Case Study Analysis: Why This Reshapes Our Understanding of How Phone Batteries Work

By treating these scientific milestones as a singular case study, we can extract three foundational principles that explain both the current engineering limitations of consumer tech and the path forward.

Principle 1: The Energy-Stability Paradox

The first and most important principle is that the very chemical process that gives high-end smartphones their incredible single-charge battery life is also the direct cause of their long-term decline.

To build a phone that is ultra-thin yet lasts 24 to 36 hours on a single charge, battery manufacturers must maximize the operating voltage and employ layered oxides (like Cobalt-heavy chemistries) that tap into oxygen's electron-donating capacity.

However, because oxygen redox destabilizes the electrostatic integrity of the cathode lattice, this high-energy state is fundamentally incompatible with extreme thermodynamic stability.

Every time a phone is fast-charged to high voltages, the system is pushed into a regime where oxygen atoms are chemically incentivized to escape, creating a self-reinforcing loop of structural decay.

                 THE ENERGY-STABILITY PARADOX
                 
        Deep Delithiation (High Operating Voltage)
                       /           \
                      v             v
       [High Energy Density]    [Instability & Decay]
       (Oxygen Redox Active)    (Oxygen Outgassing / Loss)

Principle 2: Degradation is a Systemic Lattice Failure, Not a Surface Event

Historically, battery manufacturers operated under the assumption that battery degradation was primarily a surface-level phenomenon. They believed that reactions between the highly reactive cathode surface and the liquid electrolyte were the main culprits behind capacity loss.

Consequently, industrial R&D focused almost exclusively on developing superficial surface coatings to shield the cathode from the electrolyte.

The 2026 CAS and Dundee studies prove that this approach is merely treating the symptoms rather than the disease. Oxygen loss and lattice deformation are systemic, global failures that originate deep within the bulk material.

The "holes" left by oxygen vacancies migrate through the solid crystal, triggering structural collapses from the inside out. A simple superficial coating cannot prevent a structural collapse triggered by internal, bulk-level atomic migrations.

Principle 3: Theoretical vs. Practical Voltage Limits

Modern smartphones typically charge up to a maximum voltage of 4.4 V or 4.45 V. Engineers have long wanted to push this limit higher—to 4.6 V, 4.8 V, or even the extreme 5.0 V tested by Prof. Wang's team.

Each additional millivolt unlocked represents a massive jump in energy density.

This case study demonstrates that the true limit of lithium-ion technology is not the ability of the anode to receive lithium, nor is it the conductivity of the electrolyte.

The true physical gatekeeper of battery voltage is the chemical bond between transition metals and oxygen. Pushing voltages beyond current limits without stabilizing this bond is a recipe for catastrophic capacity decay and thermal runaway, as unstable oxygen release can easily trigger explosive electrolyte combustion.

Engineering the Escape Hatch: How to Prevent Oxygen Leakage

With the atomic-level maps provided by these 2026 breakthroughs, materials scientists are no longer shooting in the dark. They are actively designing solutions to stabilize oxygen within the cathode, paving the way for next-generation devices that charge instantly and retain their health for years.

Three primary engineering methodologies have emerged to bypass the limitations of how phone batteries work.

1. Compositional Doping and Lattice Anchors

One of the most promising ways to prevent oxygen atoms from dancing out of their lattice positions is to lock them in place using "atomic anchors."

By replacing a small percentage of the cobalt or nickel atoms in a layered cathode with highly charged dopant elements—such as titanium, zirconium, niobium, or tungsten—engineers can form ultra-strong, localized ionic bonds with the surrounding oxygen atoms.

These dopant elements have a significantly higher affinity for oxygen than cobalt or nickel, especially at high states of charge. Even when a phone is deeply delithiated during a 100W ultra-fast charge, the dopant atoms hold onto the oxygen electrons, preventing the formation of unstable neutral oxygen species and blocking vacancy migration.

  compositional DOping:
  
  [Undoped Cathode (Unstable)]
  Co --- O --- Co --- O --- Co (Weak Co-O bonds allow oxygen to escape)
  
  [Doped Cathode (Stabilized)]
  Co --- O --- Ti === O === Ti (Ultra-strong Ti-O bonds anchor oxygen in place)

2. Singlet Oxygen Scavengers

For batteries utilizing next-generation Lithium-Rich Layered Oxide ($LLO$) materials—which can deliver exceptional capacities exceeding $250\text{ mAh/g}$ but suffer from severe oxygen release—manufacturers are developing internal chemistry safeguards.

One such technique involves integrating "oxygen-scavenger" materials directly into the cathode or the solid-state electrolyte interface. Compounds like sodium sulfite ($Na_2SO_3$) or iron carbonate ($FeCO_3$) can actively convert released singlet oxygen species into stable, oxidized solids before they can migrate, gather into gas pockets, or trigger structural phase changes.

While this does not prevent the initial lattice vacancy, it successfully halts the cascading thermal and mechanical breakdown of the cell.

3. Conformal Polymeric and Hybrid Solid-State Coatings

To combat the "sandwich-like" surface degradation mapped by the CAS team, engineers are moving beyond simple inorganic coatings toward highly advanced, conformal hybrid layers.

By coating the cathode particles in ultra-thin, highly elastic polymer protective layers—such as customized polysulfones or functionalized lithium polyacrylate—manufacturers can create a dual-action shield:

Mechanical Containment: The highly elastic polymer layer exerts microscopic pressure on the nanoparticle surface, physically resisting the lattice shear and "global lattice deformation" that occurs when lithium is stripped away.
Chemical Prevention: These hybrid coatings prevent direct contact between the active, oxidized surface oxygen and the highly reactive organic solvents in the liquid electrolyte, preventing the parasitic chemical reactions that lead to surface rock-salt phase transformation.

The Broader Pattern: Lessons for the Next Era of Energy Storage

Zooming out from the immediate laboratory results of late June 2026, this case study offers profound lessons that extend far beyond the battery inside a typical smartphone. It provides a blueprint for how materials science must evolve to meet the energy demands of a decarbonized society.

Lesson 1: The Transition from Metal-Centric to Anion-Active Engineering

For over three decades, battery R&D was defined by the transition metals. The industry evolved from Lithium Cobalt Oxide ($LCO$) to Nickel-Manganese-Cobalt ($NMC$), and eventually to Nickel-Cobalt-Aluminum ($NCA$) and Lithium Iron Phosphate ($LFP$).

Each iteration was essentially a remix of different transition metals, trying to optimize the balance between cost, safety, and energy density.

The Dundee, Warwick, and CAS studies demonstrate that we have largely exhausted the gains that can be made by shifting metals alone.

The next frontier of battery engineering is not metal-centric; it is anion-active.

By shifting our mental model of how phone batteries work from a metal-only electron transition process to an active metal-oxygen partnership, we can design entirely new classes of materials. Controlling the behavior of oxygen—and potentially other anions like sulfur or fluorine—will unlock capacities that were previously deemed mathematically impossible.

                 THE EVOLUTION OF BATTERY DESIGN
                 
   [1990s - 2010s: Metal-Centric]
   Focus: Shifting ratios of Co, Ni, Mn, Fe
   Status: Approaching physical thermodynamic limits
   
   [2020s & Beyond: Anion-Active]
   Focus: Controlling oxygen redox, preventing vacancy migration
   Status: Unlocking next-generation high-capacity, safe chemistry

Lesson 2: The Indispensability of Multiscale, In-Situ Imaging

One of the reasons this "secret" oxygen activity remained hidden for so long is that traditional analytical methods were completely blind to it.

If you disassemble a degraded phone battery in a dry room, expose it to air, and analyze it under a standard electron microscope, the delicate atomic rearrangements, transient oxygen vacancies, and microscopic gas phases disappear or stabilize.

The breakthroughs of 2026 were only possible because of highly specialized, multiscale imaging tools. The research teams tracked the structural decay across multiple length scales:

The Atomic Scale: Using aberration-corrected scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) to watch individual cobalt and oxygen atoms shift.
The Nanoparticle Scale: Using soft X-ray ptychographic imaging at advanced synchrotron light sources (like Lawrence Berkeley National Laboratory and SLAC) to see how entire clumps of particles behave when oxygen leaks.
The Macro Scale: Using computer simulations (density functional theory, or DFT) to model how these atomic shifts accumulate over hundreds of charge cycles.

The lesson for the broader tech sector is clear: progress in hardware is completely dependent on progress in measurement and simulation. We cannot engineer what we cannot see.

Lesson 3: The Imperative of Co-Designing Hardware and Software

As we transition to chemistries that actively utilize oxygen redox, the margin for error shrinks dramatically. Because oxygen activity is highly dependent on voltage, temperature, and charging speed, a battery can easily transition from a high-performance state to a rapid-degradation state if pushed even slightly too hard.

This means that the traditional separation between battery manufacturing and software engineering must end.

Future device manufacturers must co-design their battery chemistry alongside highly intelligent Battery Management Systems (BMS).

Instead of treating the battery as a static fuel tank, the phone’s operating system must use machine-learning algorithms to predict local lattice strain and oxygen vacancy formation in real-time.

By dynamically adjusting the charging rate, voltage cutoff, and thermal profiles based on the specific molecular state of the cathode, software can actively prevent the conditions that trigger oxygen outgassing, doubling the lifespan of the device.

What to Watch For: Upcoming Milestones and Unresolved Questions

While the discoveries of June 2026 have provided an unprecedented atomic-scale map of battery degradation, translating these laboratory breakthroughs into mass-produced consumer electronics remains a massive engineering challenge.

As the tech industry moves forward, there are several key milestones and unresolved questions to watch for:

Transition to Commercialization (Timeline: 2027–2029): Currently, the compositional doping and hybrid polymeric coating strategies required to stabilize oxygen redox are expensive and optimized only for small-scale laboratory settings. Watch for announcements from major battery suppliers (like CATL, LG Energy Solution, and Panasonic) regarding the scale-up of "oxygen-stabilized layered oxides" or "anionic-redox enabled" cells for commercial smartphones.
The Battle of Chemistries (NMC/LCO vs. LLO vs. Solid-State): Will manufacturers focus on patching existing $LiCoO_2$ and $NMC$ chemistries using the CAS global-lattice deformation stabilization models? Or will they skip straight to Lithium-Rich Layered Oxides ($LLOs$) which offer vastly superior raw capacities but require far more complex singlet oxygen scavenging?
The Solid-State Integration: Solid-state batteries, which replace the flammable liquid electrolyte with a solid ceramic or polymer layer, are often heralded as the ultimate future of energy storage. However, solid-state interfaces are highly sensitive to microscopic volume changes. If oxygen release occurs within a solid-state cell, it cannot bubble away; instead, it creates localized gas pockets that delaminate the solid interfaces, instantly killing the battery. Stabilizing oxygen chemistry is therefore a mandatory prerequisite for the success of solid-state phone batteries.
Environmental and Recycling Implications: If future cathodes are heavily doped with exotic elements like niobium, tungsten, or titanium to lock oxygen in place, how will this affect the recyclability of the cells? Current battery recycling processes are highly optimized for extracting simple cobalt, nickel, and lithium. Introducing compositionally complex lattices could complicate hydrometallurgical recycling, creating a tension between battery longevity and circular economy initiatives.

For decades, the battery inside your phone was treated as a black box—a silent, chemical engine that inevitably grew weaker with every plug-in.

Thanks to the pioneering research of June 2026, we now know that the secret to our daily charge lies in the delicate, atomic dance of oxygen.

By learning to control this invisible element, materials scientists are on the cusp of unlocking a new era of energy storage, ensuring that the devices of tomorrow remain as powerful after years of use as they were on the very first day.